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Scope

The scope of the conference is focused on the results of research and development in the field of materials engineering, experimental methods, modeling, etc, with the aim to characterize mechanical properties of

materials from nano to micro/meso-scale. Contributions on indentation and other methods for hardness and other mechanical properties assessment, measurement of deformations and stresses, time-dependent properties with

related microstructure analyses (TEM/SEM, FIB, AFM, etc.) regardless of material type (metals, ceramics, plastics, biomaterials, concrete, etc.) are welcome.

Chairs of the conference Prof. Ladislav Pešek

Assoc. Prof. František Lofaj

Scientific Board

Prof. Ladislav Pešek Prof. Ján Dusza

Assoc. Prof. František Lofaj Prof. Jaroslav Menčík (CZ)

Assos. Prof. Petr Haušild (CZ) Assoc. Prof. Jiří Němeček (CZ) Dr. Nguyen Quang Chinh (HU)

Dr. Aleš Materna (CZ).

Local Organizing Committee

František Lofaj Pavol Hvizdoš

Alexandra Kovalčíková Lenka Kvetková Petra Hviščová

Sponsors Měřicí technika Morava s.r.o. SPECION, s.r.o. Agilent Technologies ZEISS International LOMTEC BOSE KVANT

Published by: Institute of Materials Research of the Slovac Academy of Sciences in Košice, Slovac Republic Phone: +421/55/7922 457 Fax: +421/55/7922 408 E-mail: lkvetkova@imr.saske.sk http: www.tuke/lmp.sk Editors: Lenka Kvetková, Alexandra Kovalčíková, Petra Hviščová ISBN: 978-80-970964-9-6 EAN: 9788097096496

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Final Program

LOCAL MECHANICAL PROPERTIES 2014

November 12-14, 2014, Stará Lesná, High Tatras, Slovakia

Wednesday, Nov. 12, 2014

10:00 - 14:00 Registration

12:00 –14:00 Lunch

14:00 -14:15 Opening ceremony

Section: From macro to nano... 14:15-14:45 Invited lecture

Z. Németh Orogenic processes and deformation of rocks: Tectonic inspiration for materials research

14:45-15:05

J. Menčík, D. Zíta Residual stresses and energies in elastic-plastic materials after concentrated contact

15:05-15:25

F. Lofaj, D. Németh, M.Novák What happens under the indentor in brittle coatings?

15:25 – 15:45

V. Buršíková, P. Souček, P. Vašina Quasistatic and dynamic nanoindentation study of hard boron and carbon based thin films deposited on silicon substrates

15:45 - 16:15 Coffee break

Section:Films and coatings 16:15-16:35

R. Čtvrtlík, V. Kulikovsky, J. Tomáštík Effect of nitrogen concentration on mechanical properties of amorphous SiCN films

16:35-16:55

J. Buršík, V. Buršíková, Y. Jirásková Study of the mechanical properties of bilayered and single-layered CoCrFeSiB ribbons using quasistatic and dynamic nanoindentation tests

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16:55-17:15

M. Novák, F. Lofaj, P. Hviščová, R. Podoba, M. Sahul, Ľ. Čaplovič Nanohardness of DC magnetron sputtered W-C coatings as a function of residual stresses

17:15-17:35

Š. Houdková, J. Černý, Z. Pala, P. Haušild High temperature resistance of the selected HVOF coatings

17:35-17:55

J. Schubert, Z. Česánek, Š. Houdková, O. Bláhová, M. Prantnerová Influence of hot corrosion on local mechanical properties of HVOF sprayed coating based on NiCrBSi alloy

18:30-19:30 Dinner

20:00–22:00

Welcome Party + Poster Section

Thursday, Nov. 13, 2014

Section: At the tip... 9:00 - 9:30 Invited lecture

M. Ciccotti Multi-scale investigation of sub-critical crack propagation mechanisms in oxide glasses

9:30 - 9:50

V. Pejchal, M. Mueller, L. Michelet, G. Zagar, A. Singh, A. Rossoll, M. Cantoni, A. Mortensen Testing Strength and Fracture Toughness of Hard Second Phases at Micron Scale

9:50 - 10:10

T. Csanádi, M. Bľanda, N.Q. Chinh, P. Hvizdoš, J. Dusza Orientation dependent hardness and deformation mechanisms under nanoindentation of WC grains

10:10 - 10:30

J.Bočan, J. Maňák, A. Jäger Orientation-dependent mechanical properties of pure Mg and AZ31 Mg-alloy analyzed by in-situ nanoindentation

10:30 - 11:00 Coffee break

Section: (Nano)calculations... 11:00 - 11:30 Invited lecture

N.Q. Chinh Mathematical description of indentation creep and its application for the determination of strain rate sensitivity

11:30 - 11:50

D.Zita, J. Menčík Finite element analysis of elastic-plastic concentrated contact

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11:50 - 12:10

J. Michalikova, G. Mohanty, S. Michalik, J. Wehrs, J. Bednarik, H. Franz Mapping of strain-fields induced by nanoindentation using X-ray nano-diffraction

12:10-12:20 Conference photo

12:30 – 14:00

Lunch

Section: Company presentations 14:00 - 14:20

J. Nohava, M. Conte, B. Bellaton Development and the first experiments with a new high temperature nanoindenter

14:20 - 14:40

H. Pavlicek 4D Correlative workflows enabling comprehensive materials characterization

14:40 - 15:00

H. Pfaff, M. Sebastiani, R. Moscatelli, T. Brandau More than being in the right ballpark- testing the mechanical properties of microparticles

15:00-15:20

D. Novotný to be announced

15:20-15:40 A.Gába Innovation is our key issue- scratch testers, tribotesters and calotesters

15:40 - 16:10 Coffee Break

Section: Composite systems 16:10 - 16:30

P. Bouška, T. Bittner, M. Špaček, M. Vokáč Experimental investigation of flexural strength of laminated glass

16:30 - 16:50

K. Machalická, M. Eliášová Behaviour of glued connections under shear loading

16:50 – 17:10

K. Naplocha, J. Kaczmar Local strengthening of EN AC-44200 alloy with ceramic fibers

18:30-19:00 Transfer to gala dinner site

19:00 – 24:00 Conference dinner + Poster evaluation + transfer to the hotel

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Friday,

Nov. 14, 2014 Section: Toward fracture… 9:00 - 9:30 Invited Lecture

T. Chudoba The influence of the surface profile on the results of micro-scratch tests and consequences for the strength evaluation of materials

9:30 - 9:50

J. Němeček, Z. Keršner, V. Veselý, P. Schmid, H. Šimonová, L. Topolář Fracture process zone in a fine-grained cement-based composite monitored with nanoindentation and acoustic emission

9:50 - 10:10

D. Kytyr, N. Fenclova, P. Koudelka, T. Doktor, J. Sepitka, J. Lukes Mapping of local changes of local mechanical properties in trabecular connections

10:10 - 10:40 Coffee Break

Section: Miscillaneous 10:40 - 11:00

R. Mušálek, T. Tesař, J. Stráský, J. Čech Combined indentation testing of spark plasma sintered steels

11:00 - 11:20

I.Černý, J. Sís Fatigue strength and damage mechanisms of laser welded structural carbon steel sheets

11:20-11:40

M. Neslušan, T. Hrabovský, K. Kolařík, A. Mičietová Non-destructive analysis of surface after hard milling based on Barkhausen noise

11:40-12:00

M. Stodola, H. Hadraba Material structure influence when evaluating the basic material mechanical properties based on non-destructive instrumented hardness test

12:00 - 12:15 Closing ceremony

12:15 – 14:00 Lunch

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POSTERS

1. J. Balko, P. Hvizdoš, S. Hloch, J. Kľoc, P. Monka Wear and mechanical properties of various bone cements

2. M. Bednarik, D. Manas, M. Manas, M. Ovsik, J. Navratil, A. Mizera Influence of plasma treatment on the surface properties of HDPE

3. T. Bittner, Bouška, Kostelecká, Nenadálová, Rydval, Vokáč Determination of mechanical properties of non-conventional reinforcement

4. J. Bobek, J. Safka, J. Habr Mechanical properties of metal-plastic composite with internal fractal shape reinforcing structure

5. P. Burik, L. Pešek, L. Voleský Effect of pile-up on mechanical characteristics of individual phases in steels by depth sensing indentation

6. J. Buršík, V. Buršíková, M. Svoboda Local mechanical properties of Cu-Co alloys with coherent Co precipitates

7. C.Bywalski, M. Rajczakowska, L. Sadowski, M. Kaminski Evaluation of barrage lock concrete porosity using X-ray microtomography

8. K. Csach et al. Nanoindentation in metallic glasses with different plasticity

9. S. Czarnecki, J. Hola, L. Sadowski The use of a 3D laser scanner in evaluating the morphology of a sandblasted concrete surface

10. J. Čech, P. Haušild, J. Nohava Relationship between indenter calibration and measured mechanical properties of elastic-plastic materials

11. Z. Česánek, J. Schubert, O. Bláhová, Š. Houdková, M. Prantnerová Changing the local mechanical properties of satellite 6 after exposure to high temperature corrosion

12. A.Goetzke-Pala Investigations of moisture content in salt-affected brick walls by non-destructive microwave method

13. P. Haušild, M. Landa Characterization of sputter-deposited NiTi thin film by nanoindentation

14. A.Hola The moisture research of the half-timbered construction of the historic sacral building

15. M. Huráková et al. Nanoindentation study of loading rate influence on deformation of metallic glasses

16. A.Jíra, V. Králík, F. Denk, L. Kopecký Comparison of micromechanical parameters of different dental implants using nanoindentation

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17. Ľ. Kaščák, E. Spišák, J. Mucha Mechanical joining of various materials by clinching method

18. M. Kasiarova, M. Michalkova , J. Dusza, , P. Sajgalik Scratch resistance of the Si3N4-graphene nanoplatelets composites

19. L. Kocmanová, P. Haušild, A. Materna, J. Matějíček Investigation of indentation parameters near the interface between two materials

20. P. Koudelka, D. Kytyr, T. Doktor, J. Sepitka, J. Lukes Mechanical and surface properties of biocompatible materials for bone tissue engineering produced by direct 3D printing

21. C.Lamuta, G. Di Girolamo, L. Pagnotta Tribological, mechanical and microstructural characterization of plasma sprayed nanostructured YSZ coatings

22. Z. Majer, L. Náhlík, L. Malíková Particulate composite damage: The influence of particle shape on crack path

23. L. Malíková Utilization of the multi-parameter description of the crack-tip stress field in fracture mechanics tasks

24. D. Manas, M. Manas, M. Stanek, M. Ovsik, M. Bednarik, P. Kratky Nanohardness of electron beam irradiated poly (butylene terephthalate) PBT

25. D. Manas, M. Manas, M. Stanek, M. Ovsik, M. Bednarik, P. Kratky Effect of high doses of electron beam irradiated of glass-filled polypropylene on micromechanical properties of surface layer

26. M. Martinkovič, P. Pokorný Estimation of local plastic deformation in cutting zone during turning

27. A.Materna, J. Ondráček Plastic zone around fatique crack determined by FEM and nanoindentation technique

28. O. Milkovič, J. Michaliková, J. Bednarčík Influence of nanoparticle size on strain at the core-shell interface

29. J. Miškuf et.al Spontaneous nanoscale periodic stripes in metallic amorphous ribbon

30. A.Mizera, M. Manas, D. Manas, M. Ovsik, M. Stanek, J. Navratil, M. Bednarik Surface layer micro-hardness of modified LDPE by radiation cross-linking after temperature load

31. J. Navratil, M. Manas, M. Stanek, D. Manas, M. Bednarik, A. Mizera Surface properties of HDPE/HDPEx blends

32. M. Négyesi, O. Bláhová, J. Burda, J. Adámek, J. Kabátová, F. Manoch, V. Rozkošný, V. Vrtílková Influence of hydrogen content on microstructure and mechanical properties of Zr1Nb fuel cladding after high-temperature oxidation

33. J. Němeček, V. Králík Local mechanical characterization of metal foams by nanoindentation

34. D. Németh, F. Lofaj, J. Kučera Fea of the cortical bone thickness effect on the stress distribution in dental implants

35. P. Niewiadomski The effects of modifying concrete with nanoparticles in the light of literature reports

36. M. Ovsik, D. Manas, M. Stanek, M. Manas, L. Chvatalova, A. Skrobak Micro-indentation test and morphology of electron beam irradiated HDPE

37. V. Petranova, P. Koudelka, D. Kytyr, T. Doktor, J. Valach Evaluation of mechanical and microstructural parameters of multiphase materials using drift distortion corrected SEM imaging

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38. M. Reznicek, D. Manas, M. Stanek, A. Skrobak, V. Senkerik, P. Kratky Comparison of the results of creep and microindentation creep to irradiated HDPE

39. P. Rovnaníková, H. Šimonová, Z. Keršner, P. Schmid Mechanical fracture properties of cement mortars with admixtures in relation to their microstructure

40. V. Senkerik, M. Stanek, M. Manas, D. Manas, A. Skrobak, J. Navratil The behaviour of recycled material with particles of various sizes of polyamide 6 to micro hardness

41. A.Skrobak, M. Stanek, D. Manas, M. Ovsik, V. Senkerik, M. Reznicek Measuring the micromechanical properties of rubber testing samples

42. O. Sucharda, J. Brozovsky Modelling and analysis of reinforced concrete beams

43. J. Tomastik, R. Ctvrtlik, P. Bohac, M. Drab, V. Koula, K. Cvrk, L. Jastrabik Utilization of acoustic emissions in scratch test evaluation

44. J. Vácha Influence of carbon nanotubes on the mechanical properties and morphology of the different thermoplastic polymer matrices

45. Z. Pramuková, M. Kašiarová, M. Precnerová, M. Hnatko, P. Šajgalík Local mechanical properties of highly porous Si3N4 for trabecular bone replacement

46. A.Zeleňák, M. Kupková Hardness of sintered Fe-Mn samples with microgradient structure

47. P. Zubko Correlation of hardness and fatigue properties of selected steels

48. P. Hviščová Mechanical and tribological properties of HiPIMS and HiTUS W-C based coatings

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ABSTRACTS FOR PRESENTATIONS

OROGENIC PROCESSES AND DEFORMATION OF ROCKS: TECTONIC

INSPIRATION FOR MATERIALS RESEARCH

ZOLTÁN NÉMETH

State Geological Institute of Dionýz Štúr, Mlynská dolina 1, SK-847 04 Bratislava, Slovak Republic

Keywords: Rheology of rocks, ductile and brittle deformation, tectonic processes

Abstract

It is widely known that Earth represents a giant heat engine, benefiting from the heat, which

originated during formation of the planet around 4.5 billion years ago and persisted owing to

the decay of radioactive elements in its innermostparts.

Throughout the whole history of the Earth, the deformation processes acting in both - the

Earth`s mantle and in the crust, represented the principal responses on mantle convection,

acting in so-called mantle plumes. The Earth`s diameter did not change throughout its

geological history, so the continual origin of a new oceanic crust in the zones of divergence

(rift zones), was compensated with the convergence, encompassing the subduction and

collision processes. Both produced a wide range of deformed rocks (tectonites), which final

mineral composition and microstructures related on their primary mineral composition,

rheological properties of individual minerals, affecting stress field at certain temperature

and pressure conditions, as well as interaction with the fluids penetrating the deformed rock

volume. The high-grade deformed rocks became available for investigation owing to natural

exhumation processes. Because the rocks represent mainly the polymineral mixtures, in the

case of plastic (ductile) deformation, the formed mylonites provide useful information about

kinematics and P-T conditions of deformation. In the case of “cold” brittle deformation, it is

localized in disjunctive structures without change of internal setting, as well as mineral and

chemical compositions of deformed rock away of this disjunctive structure (fault, thrust

zone, etc.).

Based on author`s own investigation results, the presentation provides numerous examples

of naturally occurring deformation mechanisms and their products - deformed rocks of

various kinds - from the scale of entire continents to microscales, applying the

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methodologies of the field structural investigation, paleopiezometry, X-ray textural

goniometry, optical microscopy and EMPA microstructural observations.

RESIDUAL STRESSES AND ENERGIES IN ELASTIC-PLASTIC MATERIALS

AFTER CONCENTRATED CONTACT

J. MENČÍK, D. ZÍTA

University of Pardubice, Studentská 95, 53210 Pardubice

Keywords: Contact stresses, elastic - plastic deformations, energy, residual stresses, analysis

Abstract

If the contact stresses exceed yield strength, plastic deformations appear. Due to

inhomogeneous stress distribution, residual stresses and energies remain in the body after

unloading. This is utilised for increasing fatigue resistence by controlled mechanical surface

treatment (e.g. shot-peening). Residual stresses are also present in samples after

nanoindentation tests used for the determination of mechanical properties. Load-

penetration diagrams can show the work spent during loading (Wsp) as well as the energy

released during unloading (Wrel). Unfortunately, they do not allow simple decomposition of

the irrecoverable energy (Wir = Wsp - Wrel) into the work of irreversible processes (plastic

flow, nucleation and growth of cracks, friction, etc.) and the potential energy of residual

stresses. Nor they inform about magnitude of these stresses. The paper wants to give a

better insight into this topic. It shows principal features of contact stresses in elastic-plastic

contact, and illustrates (by means of simple examples and analytical formulae) which part of

the irrecoverable energy corresponds to the irreversible processes, and which one to

residual stresses. Both areas of application, strengthening and indentation tests are

considered. Influence of various factors is discussed.

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QUASISTATIC AND DYNAMIC NANOINDENTATION STUDY OF HARD BORON

AND CARBON BASED THIN FILMS DEPOSITED ON SILICON SUBSTRATES

V. BURŠÍKOVÁ, P. SOUČEK, P. VAŠINA

Masaryk University, Faculty of Science, Institute of Physical Electronics, Kotlářská 2 611 37 Brno, Czech Republic

Keywords: nanoindentation, dynamic mechanical analysis, thin films, magnetron sputtering, Abstract

Recently, there has been an increased interest in boron and carbon based films with X2BC

composition. Theoretical ab-initio models predict unusual combination of high stiffness and

moderate ductility for these types of films when X=Ta, Mo or W. The aim of the present

work was to prepare thin Mo2BC films at different deposition temperatures using magnetron

sputtering technique and to evaluate the dependence of their mechanical properties on the

deposition temperature. The quasistatic and nanoindentation response of the films was

studied using wide range of testing conditions. Moreover, in the present work we will

discuss the influence of the tip shape and area function used on the data obtained at very

low indentation loads (under 0,5 mN) using the quasistatic as well as the dynamic

indentation regimes.

EFFECT OF NITROGEN CONCENTRATION ON MECHANICAL PROPERTIES OF

AMORPHOUS SICN FILMS

R. ČTVRTLÍK1, V. KULIKOVSKY2, J. TOMÁŠTÍK1

1 Institute of Physics of Academy of Sciences of the Czech Republic, Joint Laboratory of Optics of Palacky University and Institute of Physics of Academy of Science of the Czech Republic, 17.listopadu 12, 772 07

Olomouc, Czech Republic 2 Institute of Physics of Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague, Czech

Republic

Keywords: SiCN, Thin films, Mechanical properties, nanoindentation Abstract

Amorphous SiCxNy thin films were deposited using reactive magnetron sputtering of SiC

target in the mixture of Ar and N gasses. The films with nitrogen content from 0 - 40 at.%

were sputtered at various N2/Ar flow ratios in the range 0 - 0.48. Films with the nitrogen

content of 0, 27 and 40 at.% were additionally annealed at 900 °C in the air and vacuum.

Analysis of mechanical properties was performed using the nanoindentation test. Raman

spectroscopy was employed for structure investigation and electron microprobe for film

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composition. The residual indents were imaged and analyzed with the laser confocal

microscope.

Hardness of the a-SiCxNy increases with the decrease of nitrogen content from approx. 22

GPa (a-SiC) to 18 GPa (a-Si30C30N40). The brittle character of the films with lower nitrogen

content was observed after annealing.

STUDY OF THE MECHANICAL PROPERTIES OF BILAYERED AND SINGLE-

LAYERED COCRFESIB RIBBONS USING QUASISTATIC AND DYNAMIC

NANOINDENTATION TESTS

J. BURŠÍKA, V. BURŠÍKOVÁB, Y. JIRÁSKOVÁA

a Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic b Department of Physical Electronics, Faculty of Science, Masaryk University, Brno, Czech Republic

Keywords: planar flow casting, depth sensing indentation, analytical electron microscopy

Abstarct

In this work we have studied local mechanical properties of CoCrFeSiB ribbons prepared by

planar flow casting (PFC). Recently improved PFC technology enabled us to use two melts

simultaneously and to prepare a bilayered Co69Fe2Cr7Si8B14/Co59Fe12Cr7Si8B14 ribbon with a

good homogeneity of the layers and well defined interface. Single-layered ribbons of the two

compositions above were prepared as well.

The microstructure and the composition profiles were studied by means of analytical

electron microscopy. Nanoindentation tests were carried out on the cross sections using the

dual head TI950 triboindenter. The nanoscale measuring head with 1nN resolution and load

noise floor below 30nN was used. Several testing modes were employed in the load range

from 0.25 to 10mN, namely quasistatic nanoindentation test, quasistatic nanoindentation

with several unloading segments, and nanodynamic mechanical analysis in the range from

0.1 to 300Hz. In situ SPM imaging was used to achieve nanometer precision positioning of

the indents and to get information about the surface topography before and after the tests.

The mechanical parameters of two sides of the bilayered sample slightly differed and they

were in good correspondence with those obtained for single-layered samples.

Acknowledgement - The Czech Science Foundation is acknowledged for the financial support (Project P108/11/1350).

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NANOHARDNESS OF DC MAGNETRON SPUTTERED W-C COATINGS AS A

FUNCTION OF COMPOSITION AND RESIDUAL STRESSES

M. NOVÁK A,B, F. LOFAJ a,b, P. HVIŠČOVÁb, R. PODOBAb, M. SAHULa, Ľ. ČAPLOVIČa

a Slovak University of Technology in Bratislava, Faculty of Materials Science and Technology in Trnava, Institute

of Materials Science, J.Bottu 25, Trnava, Slovakia b

Slovak Academy of Sciences, Institute of Materials Research, Watsonova 47, Košice, Slovakia

Keywords: nanohardness, indentation modulus, residual stress, GDOES, EDX, XRD

Abstract

The effects of chemical and phase composition of thin W-C based coatings were investigated

with the aim to find their influence on nanohardness and indentation modulus. Ten samples

of W-C based coatings were deposited on microslide glass substrates using DC magnetron

sputtering at the identical deposition parameters (power – 150 W, pressure – 0.25 Pa,

acetylene amount – 2 % and deposition time – 20 min.). Their thickness was in the range

from 500 to 650 nm. The residual stresses in the coatings varied from 1.5 GPa up to 4.4 GPa

and were measured by the technique of substrate curvature at the optical bench.

The measured absolute (relative) values from the chemical composition and phase

composition analyses were plotted against the measured values of nanohardness,

indentation modulus and residual stress. The evolution of mechanical properties was

discussed.

Fig. 1 describes the evolution of the measured nanohardness, indentation modulus and

residual stress plotted against the chemical composition evaluated by EDX.

40 45 50 55 60 65 70 75 80 85 90 95 1002Theta (°)

0

400

1600

3600

6400

10000

Inte

nsi

ty (

coun

ts)

1.5

2.0

2.5

3.0

3.5

4.0

4.5

480 500 520 540 560 580 600 620 640

95% upper confidence interval

95% lower confidence interval

95% probability

Thickness (nm)

Res

idu

al s

tres

s (G

Pa)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

15

16

17

18

19

20

21

95% lower confidence interval

95% upper confidence interval

Linear regression equation: Y = 15 + 0.9*X

HIT (

GP

a)

Residual stress (GPa) a) b) c)

Fig.1 a – XRD pattern of analysed W-C based coatings, b – Residual stress vs. thickness dependence,

c – Nanohardness vs. residual stress dependence

Acknowledgement - The authors are greatfully acknowledged for financial support from projects: APVV 0034-07, APVV 0520-10, VEGA 2/0108/11 and VEGA 2/0098/14.

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HIGH TEMPERATURE RESISTANCE OF THE SELECTED HVOF COATINGS

Š. HOUDKOVÁ, J. ČERNÝ, Z. PALA, P. HAUŠILD

Výzkumný a zkušební ústav v Plzni, Tylova 46, 301 00, Plzeň, Czech Republic

Keywords: High temperature, hardness, phase composition, HVOF, coating

Abstract

The HVOF (high velocity oxygen fuel) thermal spraying technology is widely used for creation

of coatings notable for their resistance against various kinds of loading. Depending on

sprayed material, the coatings suitable for high temperature applications can be sprayed as

well. The coatings, based on CrC or Co/ Ni alloys, offer the advantageous combination of

high temperature oxidation resistance and the wear resistance. In the paper, the attention is

paid to the evaluation of the influence of the high temperature on the coatings

microstructure and mechanical properties, namely hardness. The stability of the hardness

values in respect to the time of the high temperature exposure is presented and related to

the phase composition changes.

Acknowledgement - The paper was prepared thanks to financial support of project of Technology Agency of the Czech Republic no. TA02010486.

INFLUENCE OF HOT CORROSION ON LOCAL MECHANICAL PROPERTIES OF

HVOF SPRAYED COATING BASED ON NICRBSI ALLOY.

J. SCHUBERT, Z. ČESÁNEK, Š. HOUDKOVÁ, O. BLÁHOVÁ, M. PRANTNEROVÁ

Výzkumný a zkušební ústav v Plzni, Tylova 46, 301 00, Plzeň, Czech Republic

Keywords: NiCrBSi, coating, HVOF, hot corrosion, nanoindentation

Abstract

Ongoing increase in demands on efficiency of power plants and other facilities leads to

increased interest of new progressive materials and technologies. One of the modern

methods which lead to enhancement of surface properties is application of coatings on

surface of components composed of less quality materials. Commonly used methods

protecting components are based on some form of heat treatment. The current pressure on

increasing operating temperatures for enhanced performance of steam turbines caused

elevation of operating temperature at limit of the applicability of commonly used

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protections. From this reasons the demand for using an alternative technologies which

would provide such a desired protection rises rapidly. One of the key areas of protection in

such environment is protection against hot temperature corrosion. Possible solution can be

found in application of coatings based on alloys and cermets prepared by HVOF technology.

This paper examines local mechanical and microstructural properties of NiCrBSi coating after

exposition to extremely severe hot corrosion environment. Furthermore, the

nanoindentation measurements of NiCrBSi coating were performed before and after the

corrosion test. In this case the mixture of salts composed from 59% Na2(SO)4 with 34.5% KCl

and 6.5% NaCl was used. Temperature of test was set on 525°C and 575°C. Duration of

exposition to hot corrosion environment was 168 hours in autoclave.

MULTI-SCALE INVESTIGATION OF SUB-CRITICAL CRACK PROPAGATION

MECHANISMS IN OXIDE GLASSES

MATTEO CICCOTTI

Laboratoire PPMD/SIMM, UMR 7615 (CNRS, UPMC, ESPCI Paristech), 10 rue Vauquelin, 75005, Paris, France GAEL PALLARES, IML, Université Lyon 1, France

STEPHANE ROUX, LMT, ENS-Cachan, France LAURENT PONSON, LJLRDA, Université Pierre et Marie Curie, Paris, France

MATTHIEU GEORGE, L2C, Université Montpellier 2, France

Abstract

Fracture propagation involves the coupling of many length scales ranging from the sample

loading geometry to the molecular level. In brittle materials, the length scales of the damage

process zone are reduced to a submicrometric scale and the coupling with the macroscopic

scale is expected to be the domain of linear elastic fracture mechanics (LEFM). However,

although 2D elastic analyses are generally adequate to describe the sample deformation at

macroscopic scales, a micromechanical analysis requires the use of 3D mechanical tools due

to the crack front local curvature and to the corner point singularities at the intersection

between the crack front and the external surfaces of the sample.

We present here a thorough investigation of the slow crack growth of a sharp crack in oxide

glasses in the stress-corrosion regime [1], combining numerical and experimental analyses

from the millimetre scale to the nanoscale range. The principal aim of the study is identifying

the length and time scales of the mechanisms of damage and interaction between water and

glass, which have been the subject of an extensive debate in last decades.

16

Figure 1 – Observation of a liquid condensate at the crack

tip by AFM phase imaging

Subcritical crack propagation was performed on Double Cleavage Drilled Compression

samples under controlled atmosphere. Post-mortem and

in-situ observations were performed by optical techniques

and atomic force microscopy (AFM). A 2D/3D LEFM analysis

of this sample was realized to ensure the proper

mechanical coupling of all length scales.

The mechanical effect of capillary condensation observed

by AFM at the crack tip (Figure 1) was modeled according

to a cohesive zone model [2,3]. This allowed notably to

evaluate the negative Laplace pressure in the liquid and

to explain the crack closure mechanism in glass. The analysis of AFM in-situ images of crack

propagation by an integrated digital image correlation (DIC) technique reveals the adequacy

of the proper elastic solutions to describe the surface displacement field down to a distance

of 10 nm from the crack tip [4]. A critical analysis of the height correlation functions

performed on AFM images of the fracture surfaces does not reveal any process zone larger

than 10 nm in agreement with the conclusions of DIC. In agreement with complementary

recent observations in the literature, the length scales of damage in the stress-corrosion

fracture of glass are confined to a range of few nanometres from the crack surface.

References:

[1] M. Ciccotti, 2009. Stress-corrosion mechanisms in silicate glasses (Invited review article). J. Phys. D: Appl. Phys. 42 Art 214006

[2] Grimaldi A., George M., Pallares G., Marlière C. and Ciccotti M., 2008. The crack tip: a nanolab for studying confined liquids. Physical Review Letters. 100, Art N. 165505.

[3] Pallares G, Grimaldi A, George M, Ponson L and Ciccotti M, 2011. Quantitative analysis of crack closure driven by Laplace pressure in silica glass. J. Am. Ceram. Soc., 94 [8] 2613–2618

[4] Han K, Ciccotti M. and S. Roux, 2010. Measuring nanoscale stress intensity factors with an atomic force microscope. EPL. 89. Art 66003

17

TESTING STRENGTH AND FRACTURE TOUGHNESS OF HARD SECOND PHASES

AT MICRON SCALE

V. PEJCHAL1, M. MUELLER1, L. MICHELET1, G. ZAGAR1, A. SINGH1, A. ROSSOLL1, M. CANTONI2 AND A. MORTENSEN1

1 Laboratory of Mechanical Metallurgy, Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL),

Switzerland. 2 Interdisciplinary Centre for Electron Microscopy, École Polytechnique Fédérale de Lausanne (EPFL),

Switzerland.

Keywords: alumina, FIB machining, fracture toughness, defects

Abstract

Many alloys and composites combine a ductile matrix with discrete reinforcing phases, such

as the ceramic fibers or particles that are used in metal matrix composites. It is well

understood that the quality of the particles strongly influences strength and fracture

toughness of the composite material; however, the strength of the particulate reinforcing

phases is seldom quantified because it is challenging to measure. We present two newly

developed methods that probe, respectively, the local strength and the fracture toughness

of such microscopic phases using NextelTM 610 nanocrystalline alumina fibers produced by

3MTM, used here as testbench material. The strength measurement method involves FIB

machining of a wide rectangular notch within the fiber that is afterwards tested in

compression via nanoindenter. This produces high bending tensile stresses opposite to the

notch end, which eventually cause failure. The fracture toughness measurement method

consists of carving microscopic cantilever beams within the fiber, which contain a triangular

shaped chevron-notch, using focused ion beam micromilling. For such a beam, when loaded

via nanoindenter in bending, a crack initiates at the apex of the triangle, and subsequently

propagates stably in Mode I until it reaches a critical length at which unstable crack-growth

begins. Both test methods are complemented with three-dimensional finite element

simulation of each tested sample.

18

ORIENTATION DEPENDENT HARDNESS AND DEFORMATION MECHANISMS

UNDER NANOINDENTATION OF WC GRAINS

T. CSANÁDIA, M. BĽANDAa,b, N. Q. CHINHc, P. HVIZDOŠa, J. DUSZA a,b

aInstitute of Materials Research, Slovak Academy of Sciences, Watsonova 47, Košice, Slovakia

bFaculty of Materials Science and Technology, Slovak University of Technology, Paulínska 16, Trnava, Slovakia

cDepartment of Materials Physics, Eötvös Loránd University, Pázmány P. sétány 1/A, 1117 Budapest, Hungary

Keywords: nanoindentation; hardness; orientation dependence; EBSD; WC grain

Abstract

The orientation dependence of hardness and nanoindentation induced deformation

mechanisms of differently orientated tungsten-carbide (WC) grains in WC-Co hardmetal

were studied. Electron backscatter diffraction (EBSD) technique and nanoindentation using

continuous stiffness measurement mode were performed to determine the crystal

orientation and the load dependence behaviour of individual WC grains. The surface

morphology and the resulted deformation field around the indents were studied by atomic

force microscopy (AFM), scanning electron microscopy (SEM) and additional EBSD,

respectively. The hardness of the differently orientated WC grains showed significant angle

dependence from the [0001] basal (H= 43 ± 0.8 GPa) towards the prismatic (H= 28 ± 1.0 GPa)

directions together with a slight hardness change between the two types of prismatic and

orientations. The AFM and SEM measurements revealed sink-in and pile-up effects together

with dislocation steps on the wall of the indents in case of basal and prismatic orientations,

respectively. These observations are in good agreement with the additional EBSD results

what showed highly deformed regions close to the imprints of the indents and probably

attributing to the large number of generated dislocations. Finally, a theoretical model is

proposed in which the critical force for slip activation is determined as a function of

orientation, based on the possible slip systems of WC. The predictions using the present

model concerning the measured hardness values and sink-in effect are in good relation with

the experimental results.

19

ORIENTATION-DEPENDENT MECHANICAL PROPERTIES OF PURE MG AND AZ31

MG-ALLOY ANALYZED BY IN-SITU NANOINDENTATION

JIŘÍ BOČAN, JAN MAŇÁK, ALEŠ JÄGER

Institute of Physics of the ASCR, v.v.i., Na Slovance 1999/2, 182 21 Praha 8, Czech Republic

Keywords: Nanoindentation, mechanical properties anisotropy, magnesium, AZ31, EBSD. Abstract

Magnesium and its alloys belong amongst the lightest structural materials with high specific

strength. However, one of the disadvantages is the hexagonal close-packed (hcp) lattice

structure, which results in their anisotropic properties.

In this work, orientation dependence of mechanical properties was studied by in-situ

nanoindentation in 99.9 % pure magnesium and as-rolled AZ31 Mg-alloy (nominally 3 wt. %

Al, 1 wt. % Zn, 0.3 wt. % Mn, balance Mg). Crystallographic orientation of individual grains

was obtained by scanning electron microscope (SEM) equipped with electron backscatter

diffraction (EBSD) camera. Elastic modulus and hardness of selected grains were

subsequently determined by in-situ nanoindentation in the SEM. We show that both the

modulus and hardness increase with decreasing angle between the direction of indentation

and the c-axis of the Mg grains for both materials.

MATHEMATICAL DESCRIPTION OF INDENTATION CREEP AND ITS

APPLICATION FOR THE DETERMINATION OF STRAIN RATE SENSITIVITY

NGUYEN QUANG CHINH

Eötvös Loránd Uni., Dept of Materials Physics, Pázmány Péter sétány 1/A., Budapest, HUNGARY

Keywords: nanoindentation; creep behavior; strain rate sensitivity; power-law function

Abstract

The creep process during the holding stage of nanoindentation test has been analyzed

mathematically. It is shown analytically for the first time that the corresponding indentation

depth-time relationship can be described by a power-law function, suggesting a direct

application of nanoindentation for the determination of the strain rate sensitivity.

20

FINITE ELEMENT ANALYSIS OF ELASTIC-PLASTIC CONCENTRATED CONTACT

DUŠAN ZÍTA and JAROSLAV MENČÍK

IDIADA a.s., Pražská třída 320/8, 500 04 Hradec Králové, Czech Republic

Keywords: Contact stresses, indentation, spherical indenter, elastic – plastic deformations,

finite element analysis, residual stresses, energy

Abstract

The paper shows results of the finite element modelling of contact of a rigid spherical body

(indenter) with a body from elastic-plastic material. Both the proces of loading and

unloading are modelled. In addition to stresses, also energies are investigated, including

their distribution in the plastically deformed core and the elastically deformed outer region.

Attention is devoted to residual stresses and energies as well. Influence of various factors is

investigated, such as ratio of yield strength and elastic modulus, various values of strain-

hardening parameters (e.g. in Ramberg-Osgood model), Poisson´s ratio, relative depth of

penetration (h/R), coefficient of friction. For generality, the results are given in

nondimensional form wherever possible.

MAPPING OF STRAIN-FIELDS INDUCED BY NANOINDENTATION USING X-RAY

NANO-DIFFRACTION

J. MICHALIKOVA, G. MOHANTY, S. MICHALIK, J. WEHRS, J. BEDNARCIK, H. FRANZ

DESY, Deutsches Elektronen Synchrotron, Notkestraße 85, 22607 Hamburg. Germany

Keywords: nanoindentation, nano-diffraction, disordered materials, mechanical properties

Abstract

A novel in-situ synchrotron X-ray nanodiffraction approach for characterization and

visualization of strain fields induced by nanoindentation in amorphous materials is

introduced. In-situ experiments were performed in transmission mode using

a monochromatic highly focused sub-half-micron X-ray beam on 40 µm thick Zr-Cu-Ni-Al

based bulk metallic glasses. 2D map of strain values is obtained from diffraction data in the

area of 40 × 30 µm2 beneath the indenter in the deformed volume of Zr53Cu18.7Ni12Al16.3

BMGs. The most impacted area around the center of the strain field has radius about 7 µm.

Values of strains caused by nanoindentation using force of 1 N are about -0.6 %.

21

DEVELOPMENT AND THE FIRST EXPERIMENTS WITH A NEW HIGH

TEMPERATURE NANOINDENTER

JIŘI NOHAVA, MARCELLO CONTE, BERTRAND BELLATON

Anton Paar, Rue de la Gare 4, CH-2034 Peseux, Switzerland

Keywords: high temperature, nanoindentation, thermal drift Abstract

Instrumented indentation at moderate (up to ~400°C) and high (up to ~00°C) temperatures

presents serious challenges because of many effects such as thermal expansion of both

sample and indenter, electronic drift and oxidation of the sample and the diamond tip. For

example, drift arising due to thermal expansion of the indenter shaft can completely

overshadow the deformation data that are to be studied. Therefore, considerable

development is required to understand and take the high temperature aspects of

nanoindentation into account. The goal of this contribution is to discuss the main

technological and methodological challenges of indentation at moderate and high

temperatures using a novel nanoindentation device.

The new concept of the nanoindentation device will be described and validation results on

fused silica, polymers and bulk metallic glass will be presented. Measurements on fused

silica confirmed very good thermal stability already at temperatures up to 400°C which was

further improved by using indenter and reference heating. Experiments with Vitreloy 1 bulk

metallic glass were performed in order to show the change in its mechanical properties at

temperatures below the glass transition temperature (Tg) but mainly to show the decrease

of elastic modulus above the Tg (352°C).

22

MORE THAN BEING IN THE RIGHT BALLPARK- TESTING THE MECHANICAL

PROPERTIES OF MICROPARTICLES

HOLGER PFAFF1, MARCO SEBASTIANI2, RICCARDO MOSCATELLI2, T. BRANDAU3,

1 Agilent Technologies, Frankfurt am Main, Germany

2 University TRE, Rome, Italy

3 Brace, Karlstein am Main, Germany

Abstract

Synthetic microparticles have successfully made their way into numerous commercial

applications. Whether as carriers for catalysts or drug delivery, filter material, structural

reinforcement in composites, these materials are playing a growing role in our everyday life.

Mechanical properties play a key-role as these custom- tailored particles commonly face

various mechanical interactions with their environment as well in processing as in service.

For some of them it is crucial to maintain their structural integrity whereas others are

designed to fail in a controlled manner (e.g. drug delivery).

Assessing the mechanical properties of microscopic particles comes with diverse challenges

in respect to fixation, sample preparation and mounting. Additionally the resolutions of the

test equipment have to match the requirements for targeting and testing at small scale loads

and displacements. Any technique to encounter a specific aspect of the mechanical

behaviour has to reflect the complexity of the sample. In many cases statistical analysis has

to consider the property distribution of the particles.

In response to the growing need for mechanical characterization of micro-particles, we have

been working on different techniques utilizing a commercial nanoindentation system. We

will illustrate techniques for testing mechanical stability, different failure modes, tribological

behaviour and even the surface free energy (SFE) by recent experimental results, obtained

from a collection of micro-particles spanning a range of different materials and designs.

23

EXPERIMENTAL INVESTIGATION OF FLEXURAL STRENGTH OF LAMINATED

GLASS

P. BOUŠKA, T. BITTNER, M. ŠPAČEK, M. VOKÁČ

Czech technical University in Prague, Klokner Institute, Prague6, 166 08, Šolínova 7, Czech Republic

Keywords: annealed, glass, prestressed glass, fexural strength, laminated glass Abstract

Experimental investigation of flexural strength of laminated glass was conducted in the

laboratory conditions in Klokner Institute of Czech Technical University in Prague. They were

sandwiches of laminated glass reinforced by the most commonly used inerayers in the Czech

Republic. Characteristic values of the flexural strength were compared with the

recommendations of preliminary European standards.

BEHAVIOUR OF GLUED CONNECTIONS UNDER SHEAR LOADING

KLÁRA MACHALICKÁ, MARTINA ELIÁŠOVÁ

CTU in Prague, University Centre for Energy Efficient Buildings, Třinecká 1024, 273 43 Buštěhrad

Keywords: adhesive, glue, shear connection, artificial ageing

Abstract

An intensive research in load-bearing glass structures leads to the requirement for

performing glass-to-glass or glass-to-different material connections. Glued shear connection

is suitable for these applications mainly due to its uniform stress distribution in larger area in

comparison with bolted connections. The reliability of adhesive in the connection during the

life time of a structure is affected by many factors. The article deals with the experimental

analysis focused on the determination of material characteristics of adhesives in planar

connections, it describes the effect of various factors on the behaviour of an adhesive joint

under increasing shear loads, its ultimate load-bearing capacity and its failure modes. The

main investigated factors are the type of adhesive, the type of connected materials (material

of substrate), surface treatment and the thickness of the adhesive layer. Due to importance

of adhesive layer thickness especially in rigid and semi-rigid glues, numerical model

responding to the effect of thickness was carried out. A special part of the article describes

24

artificial laboratory ageing at glued joints, simulating five years in exterior conditions in

central Europe climate conditions.

LOCAL STRENGTHENING OF EN AC-44200 ALLOY WITH CERAMIC FIBERS

KRZYSZTOF NAPLOCHA, JACEK W. KACZMAR

Politechnika Wrocławska, 50-370 Wrocław, Wyb. Wyspiańskiego 27, POLAND

Keywords: local strengthening, mechanical properties, ceramic fibers

Abstract

The applied squeeze casting technique makes possible the local strengthening of elements

on Al alloy matrices with ceramic fibers or ceramic particles. In this paper the elaborated

technology of manufacturing of porous ceramic preforms from Saffil fibers will be shown

and technology of squeeze casting elaborated at Wrocław University of Technology

described. There will be applied the preforms characterized by porosities of 90% and 80%,

what after squeeze casting with liquid EN AC-44200 alloy produces the composite materials

containing 10 vol. and 20 vol.% of fiber strengthening. The structural phenomena at the

interface of non-strengthened alloy-strengthened alloy investigated with the optical and

electron microscopy will be discussed and the mechanical properties of manufactured

composite materials will be shown.

THE INFLUENCE OF THE SURFACE PROFILE ON THE RESULTS OF MICRO-

SCRATCH TESTS AND CONSEQUENCES FOR THE STRENGTH EVALUATION OF

MATERIALS

THOMAS CHUDOBA

ASMEC GmbH, Bautzner Landstrasse 45, 01454 Radeberg, Germany

Beside the Rockwell adhesion test, the scratch test is the standard tool for the investigation

of adhesion properties of thin hard coatings. Typically such tests are carried out using a

Rockwell C indenter with a tip radius of 200 µm and relatively high forces in the range

between 10N - 100 N. However, the results are difficult to compare since they depend on

substrate material, film thickness, scratch speed, perfectness of the tip and other

25

parameters (see [1]). Generally, such tests allow mostly a ranking of different coating

systems but no analysis of failure reasons.

In the last years modifications of the scratch test have been developed which are mainly

designed for the micro range with forces up to 2N. Tips with a radius of typically 10 µm or

smaller and precise displacement measurements with nanometer resolution allow a scan of

the surface before and after the test with the scratch tip itself. These scans can give valuable

information about the surface profile and surface failures, especially the elastic – plastic

transition. The measurement of the depth under load allows an estimation of the elastic and

plastic deformation energy, introduced into the material, and allows detecting the point of

abrupt coating failure.

However, all these data are not sufficient to understand the reason of coating failures and

their localization and to use this knowledge for the design of better coating systems. This

requires a comprehensive analysis of the local stresses [2]. The elastic parameters of all

layers and the substrate, the area function of the tip, the accurate lateral position of the tip

in relation to the rough surface and the tilting moment of the shaft, holding the tip, have to

be known for the calculation. It is further an improvement when not only the surface profile

within the scratch track is considered but the full 3D surface topography in a certain range

around the track.

Using a variety of coatings on different substrates such a stress analysis will be presented

and it will be shown how the influence of the surface profile can result in wrong conclusions

regarding the strength of coating materials.

References:

[1] REMAST, A certified reference material for the scratch test, European project SMT3 CT98- 2238, Final technical report, February 2002

[2] N. Schwarzer, Q.-H. Duong, N. Bierwisch, G. Favaro, M. Fuchs, P. Kempe, B. Widrig, J. Ramm, Optimization of the Scratch Test for Specific Coating Designs, Surface and Coatings Technology, volume 206, issue 6, year 2011, pp. 1327 - 1335

26

FRACTURE PROCESS ZONE IN A FINE-GRAINED CEMENT-BASED COMPOSITE

MONITORED WITH NANOINDENTATION AND ACOUSTIC EMISSION

JIŘÍ NĚMEČEK, ZBYNĚK KERŠNER, VÁCLAV VESELÝ, PAVEL SCHMID, HANA ŠIMONOVÁ, LIBOR TOPOLÁŘ

Czech Technical University in Prague, Thákurova 7, Praha 6,Czech Republic

Keywords: cement-based composite, fracture process zone, nanoindentation, acoustic

emission

Abstract

The contribution is devoted to the estimation of fracture process zone (FPZ) extent in a fine-

grained cement-based composite made from hydrated Portland cement. The zone

(characterized with reduced mechanical properties) is located in the vicinity of the tensile

crack developed in mechanically loaded specimens. In contrast to purely brittle materials

where the crack is localized the fracture zone in cementitious material involves larger area

dictated by its internal material length. Three-point bending test on small scale selected

cement-based composite beams with a central edge notch were employed for the tests. The

FPZ extent was monitored by means of nanoindentation using small and large indentation

matrices placed around the macroscopically observable crack. The FPZ zone extent was

estimated with an analytical model and results compared with the experiment. Acoustic

emission events were recorded along with the three-point bending test and correlated with

load-displacement data.

MAPPING OF LOCAL CHANGES OF LOCAL MECHANICAL PROPERTIES IN

TRABECULAR CONNECTIONS

DANIEL KYTYR, NELA FENCLOVA, PETR KOUDELKA, TOMAS DOKTOR, JOSEF SEPITKA, JAROSLAV LUKES

Czech Technical University in Prague, Faculty of Transportation Sciences, Department of Mechanics and Materials, Na Florenci 25, 110 00 Prague 1, Czech Republic

Keywords: trabecula, nanoindenation, bone-tissue, biomechanical properties

Abstract

Trabeculae in cancellous bone form a meshwork of intercommunicating rod like basic

structural elements. Effective biomechanical behaviour of the trabecular bone is influenced

27

not only by compositional parameters and strength of trabeculae [1,2] but also by

reinforcing/weakening effect of the joint which must not be omitted in characterization of

the bone. Furthermore understanding nature of this effect is also part of optimization

process in development of artificial bone replacements (i.e. bone scaffolds).This paper deals

with mapping of mechanical properties of human trabeculae (proximal femur, male donor,

age 38) in the interconnection area. Local changes in the connections among trabeculae are

evaluated using quasi-static nanoindenation. Groups containing several trabeculae

connected in a single joint were identified and extracted from the trabecular network and

embedded into epoxy resin. Subsequently the embedded specimens were ground to reveal

the joint and longitudinal sections of trabeculae. Quasi static nanoindenation was performed

to map local variations in the elastic properties. The indents were arranged into a

rectangular array with dimesions 100x100 microns. Then the obtained elastic modulus was

evaluated along the longitudinal axes of the connected trabeculae to compare the

mechanical properties of the trabecular tissue present in the rod parts and the connections

between trabeculae.

Acknowledgement: This research was supported by Grant No. TA01010185 of the Technology Agency from the Czech Republic, Grant Agency of the Czech Technical University in Prague (grant No. SGS12/205/OHK2/3T/16) and by institutional support RVO: 68378297.

References:

[1]MULDER, L. ET AL., BONE, 41 (2), 256–265, 2007

[2] RENDERS, G. A. P. ET AL., J BIOMECH, 44 (3), 402-407, 2011

COMBINED INDENTATION TESTING OF SPARK PLASMA SINTERED STEELS

RADEK MUŠÁLEK, TOMÁŠ TESAŘ, JOSEF STRÁSKÝ, JAROSLAV ČECH

Institute of Plasma Physics AS CR, v.v.i., Za Slovankou 3, 182 00, Praha, Czech Republic

Keywords: Spark plasma sintering (SPS), indentation mapping, stress-strain curve,

instrumented indentation, bonded-interface technique

Abstract

Spark plasma sintering (SPS) represents a modern technique for materials preparation by

compaction of powders. Unfortunatelly, typical SPS samples are quite small, which does not

allow for evaluation of their mechanical properties by conventional mechanical tests, such as

28

uniaxial tensile test. In this study, our approach based on combination of several

indentation-based techniques is presented. Hardness mapping of the sample enabled

evaluation of the sample homogeneity, indentation with multiple loads enabled construction

of stress-strain curves, instrumented indentation enabled evaluation of a depth profile of

both hardness and Young’s modulus and, finally, bonded-interface technique enabled direct

observation of the materials failure under the indent. Obtained results showed that the used

combination of relatively simple experiments may for materials prepared by SPS provide a

deeper understanding of their mechanical behavior.

FATIGUE STRENGTH AND DAMAGE MECHANISMS OF LASER WELDED

STRUCTURAL CARBON STEEL SHEETS

IVO ČERNÝ, JIŘÍ SÍS

SVÚM a.s., Tovární 2053, 25088 Čelákovice, Czech Republic

Keywords: Fatigue strength, laser welds, S 355 steel

Abstract

Laser welding is one of advanced and promising joining technologies of metallic materials,

characteristic by numerous advantages in comparison with conventional welding processes.

The technology still can be considered as fairly new and so, investigations are needed to

reach optimum properties of welds in specific application cases, depending on welding

parameters. Certification welding procedures usually require to demonstrate sufficient

microstructure, mechanical, impact loading and other characteristics, but not fatigue

resistance, which is essential for welded dynamically loaded structures. The paper contains

results of fatigue resistance investigation of laser welded 10 mm thick sheets of a carbon

structural S 355 steel. High cycle fatigue tests were performed after optimizing laser welding

parameters. Resulting endurance limit of the welds and heat affected zone was higher than

that of basic material. However, high scatter of results and different damage mechanisms

were shown for different load amplitudes. The results are discussed on the basis of

fractographical analyses, which provided some quite interesting details about crack initiation

and growth mechanisms.

29

NON-DESTRUCTIVE ANALYSIS OF SURFACE AFTER HARD MILLING BASED ON

BARKHAUSEN NOISE

MIROSLAV NESLUŠAN, TOMÁŠ HRABOVSKÝ, KAMIL KOLAŘÍK, ANNA MIČIETOVÁ

University of Žilina, Univerzitná 1, 01026 Žilina, Slovak Republic

Keywords: Barkhausen noise, hard milling, surface integrity

Abstract

This paper deals with the non-destructive evaluation of surface made hardened roll bearing

steel after hard milling via Barkhausen noise technique. The paper discusses stress and

magnetic anisotropy linked with the structure transformations with regard to variable flank

wear of cutting tool. Effective value of Barkhausen noise (BN), Peak position and FWHM

features derived from the raw BN signal as well as BN envelopes are compared with

metallographic observations and theoretical background about magnetic domains

reconfiguration when the near surface undergoes severe plastic deformation at elevated

temperatures.

MATERIAL STRUCTURE INFLUENCE WHEN EVALUATING THE BASIC MATERIAL

MECHANICAL PROPERTIES BASED ON NON-DESTRUCTIVE INSTRUMENTED

HARDNESS TEST

MARTIN STODOLA, HYNEK HADRABA

Institute of applied mechanics Brno, Ltd., Brno, Resslova 972/3, Czech Republic

Keywords: hardness testing, Vickers, imprint, indentation curve, mechanical properties, FEM

Abstract

There is a research project in IAM Brno, Ltd.The aim of this project is to develop a

methodology for evaluation of mechanical properties using NDT methods. Methodology is

developed focusing to evaluating the mechanical properties of the heterogeneous weld

structure. The material mechanical properties are determined by conducting a

nondestructive instrumented hardness testing according to Vickers. Then the developed

methodology for the basic mechanical properties determining is based on the inverse FEM

modeling principle of instrumented hardness testing when the indentation curve and the

measured surface imprint are the output of indentation. The processing of these outputs

from the experimental hardness testing processed data (the corresponding values from

indentation curve and measured surface) are not always corresponding. Then these

differences affect the accuracy of the developed methodology, because comparing the

outputs of the experimental instrumented hardness test and modeled hardness test using

FEM is achieved of the basic material mechanical properties.

30

ABSTRACTS FOR POSTERS

WEAR AND MECHANICAL PROPERTIES OF VARIOUS BONE CEMENTS

J. BALKO1, P HVIZDOŠ1, S. HLOCH2,3, J. KĽOC4, P. MONKA2 1Institute of Materials Research, Slovak Academy of Sciences, Košice, Slovakia

2Faculty of Manufacturing Technologies, Technical University Košice with a seat in Prešov

3Prešov, Slovakia

4Faculty of Health Care of Prešov University, Prešov, Slovakia

Keywords: bone cement, wear, nano-indentation, saline

Abstract

Several bone cements with different compositions were prepared using various preparation

methods. Wear and wear properties were studied in liquid medium (saline) using ball-on-

disc method with alumina ball as a counterpart carried out on the THT Tribometer CSM

Instruments (Switzerland) and compared to the results obtained in dry sliding conditions.

(Nano)hardness was measured both in dry conditions and in lubricant (saline) Wear and

microstructure was observed by 3D optical profiler PLu neox Sensofar (Spain) and scanning

electron microscope Tescan VEGA3 LMU (Czech Republic). The results obtained for different

types of bone cements were compared and also were discussed with respect of mixing

method.

Acknowledgements - The authors are acknowledged for financial support from projects APVV – 0108-12 and VEGA 2/0075/13.

INFLUENCE OF PLASMA TREATMENT ON THE SURFACE PROPERTIES

OF HDPE

M. BEDNARIK, D. MANAS, M. MANAS, M. OVSIK, J. NAVRATIL, A. MIZERA

Tomas Bata University in Zlin, nám. T.G. Masaryka 275, 762 72 Zlin, Czech Republic

Keyword: surface energy, contact angle, microhardness, HDPE, plasma

Abstract

The high-density polyethylene (HDPE) is currently one of the most used polymers. However,

the use of HDPE is to same extend limited by its non-polar character and low surface energy,

which results in poor surface and adhesion properties. One solution to this problem is a

31

plasma surface treatment, which increases the surface energy, and improves surface

properties.

This paper describes the effect of plasma surface treatment on the surface energy,

wettability, and microhardness of HDPE.

DETERMINATION OF MECHANICAL PROPERTIES OF NON-CONVENTIONAL

REINFORCEMENT

T. BITTNER, BOUŠKA, KOSTELECKÁ, NENADÁLOVÁ, RYDVAL, VOKÁČ

Klokner Institute, CTU in Prague, Šolínova 7, Prague, Czech Republic

Keywords: Non-Conventional Reinforcement, Textile Glass Reinforcement, Basalt

Reinforcement, Modulus of Elasticity, Tensile Strength

Abstract

Mechanical tests of samples of basalt and textile glass reinforcement were performed in the

Klokner Institute within the solution of the research project GAČR 13-12676S. These tests

were carried out because of the need to establish elementary mechanical quantities that are

tensile strength and modulus of elasticity of non-conventional reinforcement. Both of these

quantities are required for further modeling of structures and for designing of the elements

made from textile reinforced concrete (TRC) as not being provided by reinforcement

manufacturers. The tests were carried out on a total of 12 samples of reinforcement where

the first 6 samples were made from textile glass reinforcement (AR-G = Alkali-Resistant

Glass) and the remaining 6 samples were prepared from basalt reinforcement. The filament

sheaf fibers called roving was used for the production of test specimens. The sample of the

textile glass reinforcement was produced by the V. FRAAS, GmbH, Germany and the sample

of basalt reinforcement was supplied by the BASALTEX, a.s. firm.

32

MECHANICAL PROPERTIES OF METAL-PLASTIC COMPOSITE WITH

INTERNAL FRACTAL SHAPE REINFORCING STRUCTURE

J.BOBEK, J.SAFKA, J.HABR

Technical Univrsity of Liberec, Industrial Technologies Department, Studentska 2, Czech Republic

Keywords: Metal, 3D print, composite, fractal shapes,mechanical properties.

Abstract

This paper deals with mechanical properties research of innovative polymer multiphase

metal and polymer composite materials consisting of matrix and isotropic or anisotropic

oriented deterministic fractal shapes made by 3D printing. By creating of reinforcing internal

structure consisting of deterministic fractal connected shapes is possible to gain unlimited

mechanical properties directing. These fractal shapes - placed in multiphase system matrix -

are significantly influencing whole material system mechanical properties mainly in case of

stress on the limit of strength, proportional elongation on the limit of strength or tensile/

flexural modulus. Fractal shapes are also possible to properly locate, orient or shape modify

according to potential material using with goal to gain maximal efficiency of fractal shapes

occurrence. Producing of this multiphase system is realized by the help of 3D printing

technology. Internal fractal shape structure is 3D printed from aluminium. This feature is in

the next step over injected by polymer. So is possible to create any fractal shapes placed in

polymer matrix which are by another technology unmanufacturable. Mechanical properties

analyse is performed with respect to fractal shape type, fractal dimension, and fractal

shape orientation.

33

EFFECT OF PILE-UP ON MECHANICAL CHARACTERISTICS OF INDIVIDUAL

PHASES IN STEELS BY DEPTH SENSING INDENTATION

PETER BURIK1, LADISLAV PEŠEK2 and LUKÁŠ VOLESKÝ1

1Technical University of Liberec, Faculty of Mechanical Engineering, Department of Material Science,

Studentská 2, 461 17 Liberec, Czech Republic 2Technical University of Košice, Faculty of Metallurgy, Department of Materials Science, Letná 9, 042 00 Košice,

Slovakia

Keywords: pile-up, hardness, Young’s modulus, Berkovich diamond indenter, atomic force

microscopy, steel sheets

Abstract

Mechanical properties measured by depth sensing indentation are derived from the

indentation load-displacement data used a micromechanical model developed by Oliver &

Pharr (O&P). The applicability of O&P analysis, developed from a purely elastic contact

mechanics (sink-in) is limited by the materials pile-up. However, when it does, the contact

area is larger than that predicted by elastic contact theory (material sinks-in during purely

elastic contact), and both hardness, H, and Young’s modulus, E, are overestimated, because

their evaluation depends on the contact area deduced from the load-displacement data. H

can be overestimated by up to 60 % and E by up to 30 % depending on the extent of pile-up

[1,2]. It is therefore important to determine the effect of pile-up on obtained mechanical

characteristics by depth sensing indentation.

The work experimentally analyses the effect of pile-up height on mechanical characteristics

H and E of individual phases in steels, which are determined by O&P analysis, and the effect

of grain boundaries on the shape and size of the pile-up lobes. Pile-up height was measured

by atomic force microscopy (AFM).

Acknowledgment - The paper was supported partly by the Project OP VaVpI Centre for Nanomaterials, Advanced Technologies and Innovation CZ.1.05/2.1.00/01.0005, partly by the Project Development of Research Teams of R&D Projects at the Technical University of Liberec CZ.1.07/2.3.00/30.0024 and partly by the VEGA project No. 1/0582/13 at the Technical University of Košice, Slovakia.

References

[1] L.N. Zhu, B.S. Xu, H.D. Wang, Measurement of mechanical properties of 1045 steel with significant pile-up by sharp indentation, J Mater Sci. 46 (2011), pp. 1083–1086.

[2] J.L. HAY, Instrumented Indentation Testing, ASM Handbook 8, Mechanical Testing and Evaluatio 236, (2000), pp. 232-244.

34

LOCAL MECHANICAL PROPERTIES OF Cu-Co ALLOYS

WITH COHERENT Co PRECIPITATES

JIŘÍ BURŠÍKA, VILMA BURŠÍKOVÁB, MILAN SVOBODAA

a Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic b Department of Physical Electronics, Faculty of Science, Masaryk University, Brno, Czech Republic

Keywords: microstructure, precipitation, depth sensing indentation, analytical electron microscopy

Abstract

In this work the local mechanical properties of thermal treated diluted Cu-Co alloys with 4

at.% of Co were investigated. The samples underwent solution annealing at 1273 K, water

quenching and further thermal treatment in the range 873 to 1073 K. During this sequence a

fine distribution of Co-rich precipitates was generated. Parameters of microstructure were

evaluated by means of analytical electron microscopy. The diameter of the precipitates was

around 60-80 nm with mean particle distance around 300 nm.

The main emphasis was placed on detailed characterization of fine microstructural features

by means of local nanoindentation tests of mechanical properties using Hysitron TI950

triboindenter. The combination of nanoindentation technique with in situ scanning probe

microscopy ensured that the measurement sites could be selected in the microstructure

with nanometer accuracy. The nanoscale mechanical properties of precipitates, areas

adjacent to the precipitates and precipitate-free zones were studied. Large area grid

indentation tests were carried out with different applied loads in the range from 50 to

500µN. Moreover, the modulus mapping capability was applied to obtain quantitative maps

of the storage and loss stiffness and modulus.

Acknowledgement - The Czech Science Foundation is acknowledged for the financial support (Project P108/11/2260).

35

EVALUATION OF BARRAGE LOCK CONCRETE POROSITY USING X-RAY

MICROTOMOGRAPHY

CZESŁAW BYWALSKI, MAGDALENA RAJCZAKOWSKA, ŁUKASZ SADOWSKI, MIECZYSŁAW KAMIŃSKI

Faculty of Civil Engineering, Wrocław University of Technology

Abstract

This paper deals with the use of X-ray microtomography in evaluating the porosity of barrage

lock concrete. The main parts of the lock were built in the years 1914-1917. Its high and low

heads were founded on a 2.70 m thick concrete slab. Samples for laboratory tests were

taken by core drilling at half of the slab thickness. The compressive strength of the concrete

was determined and the porosity of the concrete was evaluated using X-ray

microtomography. The compressive strength values ranged from 17.3 to 37.3 MPa. The

porosity examination results are compared with the destructively determined concrete

compressive strength values.

NANOINDENTATION IN METALLIC GLASSES WITH DIFFERENT PLASTICITY

KORNEL CSACH, et al. UEF SAV, Watsonova 47, 040 01 Košice, Slovakia

Keywords: amorphous metals, nanoindentation, creep, structural relaxation

Abstract:

The nanoindentation and thermomechanical experiments on two types of metallic glasses

with different glass forming ability were made. The nanoindentation behaviour at room

temperature was associated with the creep at elevated temperatures for both types of

alloys. The differences in mechanical properties due to the structural relaxation processes in

these alloys were studied too.

36

THE USE OF A 3D LASER SCANNER IN EVALUATING THE MORPHOLOGY OF A

SANDBLASTED CONCRETE SURFACE

SŁAWOMIR CZARNECKI, JERZY HOŁA, ŁUKASZ SADOWSKI

Faculty of Civil Engineering, Wrocław University of Technology

Keywords: concrete, morphology, 3D laser scanner, sandblasting

Abstract

This paper presents the use of a novel 3D laser scanner in evaluating the morphology of a

concrete surface subjected to sandblasting. The results of examinations carried out by

means of the scanner are compared for an untreated concrete surface and the sandblasted

concrete surface. The scanning results are presented in the form of three-dimensional

images and several surface morphology parameters determinable using this technique.

RELATIONSHIP BETWEEN INDENTER CALIBRATION AND MEASURED

MECHANICAL PROPERTIES OF ELASTIC-PLASTIC MATERIALS

JAROSLAV ČECH, PETR HAUŠILD, JIŘÍ NOHAVA

Czech Technical University in Prague – Faculty of Nuclear Sciences and Physical Engineering – Department of Materials, Trojanova 13, 120 00 Praha 2, Czech Republic

Keywords: instrumented indentation, area function, elastic-plastic material

Abstract

Values of mechanical properties (e.g., hardness, Young’s modulus) measured by

instrumented indentation technique can be strongly influenced by the elastic-plastic

properties of the tested material. It is caused by the shape of the contact area which is

different from the theoretical shape used in the Oliver-Pharr analysis. This phenomenon can

be reduced by the calibration of the indenter area function on different standard materials

(ceramics, metals) with the similar elastic-plastic behavior as the materials under

investigation. In the presented work, this simple method was used to improve the

measurement of mechanical properties for several materials.

37

CHANGING THE LOCAL MECHANICAL PROPERTIES OF STELLITE 6 AFTER

EXPOSURE TO HIGH TEMPERATURE CORROSION

Z.ČESÁNEK, J.SCHUBERT, O.BLÁHOVÁ, Š. HOUDKOVÁ, M.PRANTNEROVÁ

Research and Testing Institute Plzen s.r.o., Tylova 1581/46, 301 00 Plzeň, Czech Republic

Abstract

Stellite 6, High Temperature Corrosion Coating properties determine its behavior in

operation. The simulation of future operational conditions is therefore the best quality test.

This evaluation method is usually not possible to perform, and the coatings are therefore

frequently characterized by their physical or mechanical properties. This text deals with the

high-temperature corrosion of Stellite 6 coating, which is a CoCrW based coating and with

changes of its local mechanical properties before and after corrosion testing. High

temperature corrosion is the corrosion in the presence of molten salts. In this case, the

mixture of salts in composition of 59% Na2(SO)4 with 34.5% KCl and 6.5% NaCl was used.

Two exposure temperatures 525 °C and 575 °C were selected and the tests in both

temperatures were performed in the time interval of 168h autoclave.

The coating with salt mixture layer was analyzed with scanning electron microscopy and

nanoindentation. The high temperature resistance of Stellite 6 coating was evaluated by the

changes in coating surface and by the occurrence of individual phases formed on the coating

surface during the test. Generally, it can be said that the Stellite 6 alloys deposited by HVOF

technology show selective oxidation under the salt film. This fact was also proved in this

case. Furthermore, the nanoindentation measurements of Stellite 6 coating were performed

before and after the corrosion test. These measurements were used to evaluate the change

of local mechanical coating properties.

38

INVESTIGATIONS OF MOISTURE CONTENT IN SALT-AFFECTED BRICK WALLS BY

NON-DESTRUCTIVE MICROWAVE METHOD

ADELAJDA GOETZKE-PALA

Politechnika Wrocławska, Instytut Budownictwa, Wybrzeże Wyspiańskiego 27, Wrocław, POLAND

Keywords: brick walls dampness, salinity, microwave moisture meter

Abstract

This paper presents investigations of the mass moisture content in saline brick walls carried

out using the microwave method. Brick wall samples placed in respectively a nitrate,

chloride and sulphate water medium and in a reference water medium were investigated.

The samples were investigated using the nondestructive microwave method by means of a

T600 moisture meter, after they were saturated to a constant mass. Subsequently they were

placed in a climatic chamber and subjected to multistage drying to a constant mass. After

each drying stage the samples were weighted and their moisture content was determinate

using the microwave moisture meter. It was found that due to salinity the brick wall

moisture content evaluated by the nondestructive microwave method differed from real

moisture content value. Dependencies between mass moisture content Wm and reading X of

the microwave meter used in the investigations were determined.

CHARACTERIZATION OF SPUTTER-DEPOSITED NiTi THIN FILM

BY NANOINDENTATION

P. HAUŠILD, M. LANDA

Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Department of Materials, Trojanova 13, 120 00 Praha, Czech Republic

Keywords: NiTi, shape memory alloys, nanoindentation

Abstract

NiTi shape memory alloy thin film sputter-deposited on alarge scale silicon wafer was

characterized by means of instrumented (depth-sensing) indentation technique. Thickness of

deposited thin film was measured by calottes device. Microstructure of thin film was

observed using differential interference (Nomarski) contrast. It was shown that the local

mechanical properties are different in areas containing different phases (austenite and

39

martensite) according to different deposition conditions (kinetic energy of deposited atoms

when impacting the substrate surface).

THE MOISTURE RESEARCH OF THE HALF-TIMBERED CONSTRUCTION OF THE

HISTORIC SACRAL BUILDING

ANNA HOŁA

Wrcław University of Technology, Faculty of Civil Engineering, Wybrzeże Wyspiańskiego 27, Wrocław, Polska

Keywords: half-timbered construction, historic building, moisture, non-destructive testing,

dielectric method, resistive method

Abstract

The paper presents the research results of the dampness condition of masonry and wooden

structural elements of historic sacral building made after nearly a hundred years of its

operation. Due to limited possibilities of interference into the structure of the historic

building, the examination has been performed by means of non-destructive methods:

dielectric and resistive. The studies have shown excessive moisture of investigated elements

that contributed to their destruction by frost and biological corrosion. The results of the

research has been used to develop an effective moisture protection as well as the scope of

the repair work.

NANOINDENTATION STUDY OF LOADING RATE INFLUENCE ON

DEFORMATION OF METALLIC GLASSES

M. HURÁKOVÁ et al.

UEF SAV, Watsonova 47, 040 01 Košice, Slovakia

Keywords: metallic glasses, nanoindentation, displacement bursts

Abstract

The measurement of mechanical properties of metallic glasses by nanoindentation

equipment offers the observation of hardening and recovery in these materials. The

transition from the elastic to the plastic deformation indicates another interesting feature of

inhomogeneous deformation during nanoindentation, continuous serrations (serial pop-ins -

40

sudden displacement excursion) in P-h curve under controlled instrumented

nanoindentation conditions. It is assumed that the serrations are associated with the shear

band nucleation and their propagation. In addition it was shown that discrete flow was

strongly dependent on the indentation loading rate. We can see that the serrations in the P-

h curve are more pronounced at lower loading rates and gradually disappear with the

increasing rate. From Displacement-Load curve and pop-in events we calculated the

contribution of inhomogeneous plastic deformation in dependence on the loading rate and

the indenter type.

COMPARISON OF MICROMECHANICAL PARAMETERS OF DIFFERENT DENTAL

IMPLANTS USING NANOINDENTATION

ALEŠ JÍRA, VLASTIMIL KRÁLÍK, FRANTIŠEK DENK, LUBOMÍR KOPECKÝ

Keywords: nanoindentation; dental implant; hydroxyapatit, reduced modulus

Abstract

The aim of this work is the description of microstructure and comparison of

micromechanical properties of cylindrical shaped intraosseous parts of dental implants with

plasma modified surface and with threaded modification. Differences in elastic parameters

(such as reduced modulus (Er) and hardness (H)) of investigated implants within the

supporting part of the shaft and surface layer in two different directions (proximal and

lateral) are compared using experimental method of nanoindentation. Casted implants of

bioceramics (threaded surface) and machined implants of titanium alloys Ti6Al4V with

plasma modified surface of hydroxyapatit (HA) Ca10(PO4)6(OH)2 from different batches of

product were available for measurement. SEM element analysis revealed a heterogeneous

structure and various concentrations of the essential chemical elements (C, O, P, Ca) on the

surface of implants. Results of elastic moduli and hardness was monitored in different

locations. On a large statistical set of measurements was indicated that average reduced

modulus of implant shafts of bioceramics is approximately 258 GPa and of titanium alloys

about 126 GPa. Differences of Er in case of peripheral hydroxyapatite layer are in range of

~145 GPa – ~163 GPa according to the exact composition of surface modification in the

individual batches of the product. The difference of measured values on individual samples

in a proximal/lateral direction is approximately 10%.

41

MECHANICAL JOINING OF VARIOUS MATERIALS BY CLINCHING METHOD

ĽUBOŠ KAŠČÁK, EMIL SPIŠÁK, JACEK MUCHA

Technical University of Košice, Faculty of Mechanical Engineering, Department of Technology and Materials, Mäsiarska 74, 040 01 Košice, Slovakia

Keywords: clinching, carrying capacitym microhardness

Abstract

The paper deals with evaluation of properties of the joints made by method of mechanical

joining of materials – clinching. The joint is made between a punch and a die without any

additional elements. This method is mainly used as an alternative to resistance spot welding.

The high-strength dual-phase steel sheet DP600 in combination with drawing grade steel

sheets DC06, DX53D+Z and DX51D+Z were used for experiments. The samples with single

clinched joint and the samples with double clinched joints were prepared for the

experiments. The influence of orientation of joined materials according to punch and die on

the carrying capacities of the clinched joints was observed too. The tensile test,

metallographicall analysis and microhardness test were used for the evaluation of joint

properties.

INVESTIGATION OF INDENTATION PARAMETERS NEAR THE INTERFACE

BETWEEN TWO MATERIALS

L. KOCMANOVÁ, P. HAUŠILD, A. MATERNA, J. MATĚJÍČEK

Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Department of Materials, Trojanova 13, 120 00, Praha 2, Czech Republic

Keywords: nanoindentation, finite element method, composite

Abstract

The paper participates in a development of composits. Tungsten-steel composite is studied

as materials suitable for a first wall of tokamak, FeAl + Al2O3 composite is considered as a

possible material for fourth generation of nuclear power plants and Al2O3 + YSZ composite is

a potential implant material. The focus of our study is change of material properties near the

interface and a determination of area size which is influenced by the adjacent material.

Material properties are investigated by nanoindentation. The task is simulated using finite

element method. Elastic modulus is determined in dependence of a distance from the

interface between the materials and the indenter’s tip. The distance between the interface

42

and the indenter’s tip is normalized by the indentation depth. Due to elasticity, all

normalized results of hardness and modulus lie on one curve. The curve is approximated by

inverse beta function. The simulated results were verified experimentally.

MECHANICAL AND SURFACE PROPERTIES OF BIOCOMPATIBLE MATERIALS

FOR BONE TISSUE ENGINEERING PRODUCED BY DIRECT 3D PRINTING

PETR KOUDELKA, DANIEL KYTYR, TOMAS DOKTOR, JOSEF SEPITKA, JAROSLAV LUKES

Department of Biomechanics, Institute of Theoretical and Applied Mechanics, v.v.i., Academy of Sciences of the Czech Republic, Prosecka 76, 190 00 Prague 9, Czech Republic

Keywords biocompatibility, nanoindenation, mechanical properties, surface, additive

manufacturing

Abstract

In recent orthopaedic practice repairs of defective bones are the most commonly carried out

using autografts and allografts. Although used for many years natural grafts possess several

limitations and potential for complications due to various influences including donor site

morbidity, loss of bone inductive factors, resorption during healing, etc. To overcome these

problems implants in form of artificial bone scaffolds manufactured using biocompatible

material represent an attractive alternative.

In this work factors influencing biocompatibility and primary stability of implants

manufactured from polylactic acid (PLA) using direct 3D printing are assessed using

nanoindentation. Even though mechanical characteristics of PLA itself are well known

influence of production parameters (printing speed, filling ratio, etc.) on mechanical

properties of implants has to be evaluated. For this reason a set of prismatic samples printed

with different printer settings are subjected to nanomechanical measurement. Both quasi-

static and dynamic methods are employed to identify modulus and hardness distribution on

surface and within the samples. Moreover mechanical properties along scanning direction

and interlayer characteristics are assessed. Roughness and scratch measurements are

carried out in order to obtain data necessary for assessment of contact behaviour on the

implant/bone interface after surgical treatment and ultimately primary stability of the

implant.

43

TRIBOLOGICAL, MECHANICAL AND MICROSTRUCTURAL CHARACTERIZATION

OF PLASMA SPRAYED NANOSTRUCTURED YSZ COATINGS

CATERINA LAMUTA, G. DI GIROLAMO, L. PAGNOTTA

University of Calabria, Ponte P. Bucci, cubo 44C, Rende (CS), Italy

Keywords: hardness, indentation, plasma spraying, thermal barrier coatings, Young’s

modulus, wear, zirconia

Abstract

Zirconia-based ceramic coatings can be used for thermal protection of hot-section metal

components of turbine engines and they are also excellent biomaterials for clinical

application. The presence of nanostructures, deriving from partial melting of nanostructured

powder feedstock, represents an interesting technological solution in order to improve their

functional characteristics. In this work nanostructured yttria stabilized zirconia (YSZ) coatings

were deposited by air plasma spraying. The influence of the main process parameters on

their microstructural, mechanical and tribological properties was investigated by scanning

electron microscopy, indentation and wear tests. Their porous microstructure was

composed of well melted overlapped splats and partially melted nanostructured areas. This

bimodal microstructure led to a bimodal distribution of the mechanical properties. An

increase of plasma power and spraying distance was able to produce denser coatings, with

lower content of embedded nanostructures, which exhibited higher mechanical and

tribological characteristics.

PARTICULATE COMPOSITE DAMAGE: THE INFLUENCE OF PARTICLE SHAPE ON

CRACK PATH

Z. MAJER, L. NÁHLÍK, MALÍKOVÁ

Brno University of Technology, Technicka 2896/2, 616 69 Brno,Czech Republic

Keywords: particulate composites, crack propagation, finite element method, interphase

Abstract

In recent years, particle reinforced composites are widely used due their mechanical

properties as construction materials. The paper is mainly focused on the estimating of the

influence of particle shape on the micro-crack propagation in polymer matrix. Material

44

properties of the matrix and particles was obtained from the experiment and a two-

dimensional numerical model was developed in finite element software Ansys. The

calculations was done based on the assumption of the linear elastic fracture mechanics.

UTILIZATION OF THE MULTI-PARAMETER DESCRIPTION OF THE CRACK-TIP

STRESS FIELD IN FRACTURE MECHANICS TASKS

LUCIE MALÍKOVÁ

Brno University of Technology, Brno, Czech Republic

Keywords: Crack-tip stress field, Williams expansion, higher-order terms, fracture

mechanics, plastic zone

Abstract

Multi-parameter description of the local crack-tip stress field is introduced in the paper. It is

shown that it can be very useful when the stress intensity factor is not considered as the

single-controlling parameter of the near-crack-tip fields. Several initial terms of the so-called

Williams expansion (derived for description of the stress state near the crack tip) are

calculated via the over-deterministic method, a regression technique based on least squares

formulation which is applied on outputs of conventional FE analysis. As an example, the

approximation of the stress tensor and displacement vector, respectively by means of the

power series is used for estimation of the plastic zone extent in a cracked specimen. From

the more general point of view, the paper should show how important the higher-order

terms coefficients are for accurate knowledge of the local stress/displacement fields, which

are furthermore the basic inputs for more advanced fracture mechanics technique.

45

NANOHARDNESS OF ELECTRON BEAM IRRADIATED POLY (BUTYLENE

TEREPHTHALATE) PBT

DAVID MANAS, MIROSLAV MANAS, MICHAL STANEK , MARTIN OVSIK , MARTIN BEDNARIK , PETR KRATKY

aTomas Bata University in Zlin, Nam. T.G. Masaryka 5555, Zlin, 760 01 Czech Republic

Keywords: nanohardness, (polybutylene terephthalate) PBT, electron beam irradiation,

surface layer

Abstract

Poly (butylene terephthalate), PBT, is a commercially important engineering polymer with a

wide range of applications such as injection molding and extrusion. As a member of the

polyester family, it is also often used as the matrix material in glass fiber reinforced

composites, having attractive mechanical properties, good moldability and fast

crystallization rate. PBT has some processing advantages over its chemical relative, poly

(ethylene terephthalate), PET. The melting temperature of PBT is about 230 °C, which is

lower than PET, (ca. 270 °C), allowing PBT to be processed at lower temperatures. In

addition, PBT has a lower glass transition temperature, a faster crystallization rate.

The irradiation cross-linking of thermoplastic materials via electron beam or cobalt 60

(gamma rays) proceeds is proceeding separately after the processing. The cross-linking level

can be adjusted by the irradiation dosage and often by means of a cross-linking booster .

The principle of the radiation process is the ability of the high energy radiation to produce

reactive cationts, anoints and free radicals in the material. The industrial application of the

radiation process on polymer and composites includes polymerization, crosslink-linking and

degradation. The radiation process involves mainly the use of either electron beam from

electron accelerators or gamma radiation from Cobalt – 60 sources.

Experimental study deals with the influence of beta radiation on the micromechanical

properties of the surface layer of PBT with 5% crosslinking agent addition. When subjecting

the PBT to beta radiation, the structure as well as the surface layer show structural changes

(crosslinking, degradation). The injected specimens were irradiated by doses of 0, 33, 45, 66

and 99 kGy. There was an improvement in some micromechanical properties of the surface

layer of PTB. The improvement/deterioration of micromechanical properties of surface layer

46

of PBT measured by the instrumented nanohardness test, FTIR and WAXS is the content of

this experimental study.

Acknowledgments – This paper is supported by the internal grant of TBU in Zlin No. IGA/FT/2014/016 funded from the resources of specific university research and by the European Regional Development Fund under the project CEBIA-Tech No. CZ.1.05/2.1.00/03.0089 and Technology Agency of the Czech Republic as a part of the project called TA03010724 AV and EV LED luminaire with a higher degree of protection.

References

1.Manas D., Manas M., Stanek M., Danek M.: Arch. Mater. Sci. Eng., 32 (2), pp. 69-76, (2008). 2. Uzuna O.;Kölemena U.; Çelebi S.; Güçlü N.: Journal of the European Ceramic Society 25, 969–977, (2005)

EFFECT OF HIGH DOSES OF ELECTRON BEAM IRRADIATED OF GLASS-FILLED

POLYPROPYLENE ON MICROMECHANICAL PROPERTIES OF SURFACE LAYER

DAVID MANAS, MIROSLAV MANAS, MICHAL STANEK , MARTIN OVSIK ,

MARTIN BEDNARIK, PETR KRATKY

aTomas Bata University in Zlin, Nam. T.G. Masaryka 5555, Zlin, 760 01 Czech Republic

Keywords: microhardness, glas-filled polypropylene, electron beam irradiation, surface layer

Abstract

Polymer materials can undergo structural changes under radiation, e.g. due to infrared (IR),

microwave and ultraviolet (UV) as well as gamma ray or electron beam (EB) exposure.

Depending on the irradiation type and on the polymer materials, crosslinking reactions or

degradation can take place in the polymer. Since the 1960s, EB radiation has been used to

cure thermosetting polymers. Compared with conventional curing methods, it permits a

rapid curing of thicker parts at low temperature. Furthermore, the emission of volatile

agents can be drastically reduced.2 Because of these advantages, considerable interest has

been demonstrated and numerous studies have been conducted by different researchers on

EB curing of thermosets and thermoset-based composite materials. Walton et al. reported a

new formulation of rapid EB curable resins to be used in composite manufacturing

techniques such as resin transfer moulding, filament winding and pultrusion. Roylance et al.

studied EB radiation curing of braided composite structures in a resin transfer moulding

(RTM) process for aerospace application. In 1997, Guasti et al. described a new patented

method for the EB curing of filament wound composites, a socalled ‘layer-by-layer EB

47

curing’. In a similar way, Foedinger et al. presented results about EB curing of filament-

wound graphite/epoxy pressure vessels. In contrast to thermosetting resins, thermoplastic

materials are not crosslinked. They can be softened and hardened reversibly by changing the

temperature. Fabrication processes like injection moulding, extrusion and blow moulding

take advantage of this feature to shape thermoplastic polymers into complex components.

However, they don’t exhibit the advantages of crosslinked structures such as high stiffness,

high strength, temperature and chemical resistances.

The irradiation cross-linking of thermoplastic materials via electron beam or cobalt 60

(gamma rays) proceeds is proceeding separately after the processing. The cross-linking level

can be adjusted by the irradiation dosage and often by means of a cross-linking booster .

The principle of the radiation process is the ability of the high energy radiation to

produce reactive cationts, anoints and free radicals in the material. The industrial application

of the radiation process on polymer and composites includes polymerization, crosslink-

linking and degradation. The radiation process involves mainly the use of either electron

beam from electron accelerators or gamma radiation from Cobalt – 60 sources.

Experimental study deals with the influence of beta radiation on the micromechanical

properties of the surface layer of glass-filled with 5% crosslinking agent addition. When

subjecting the glass-filled PP to beta radiation, the structure as well as the surface layer

show structural changes (crosslinking, degradation). The injected specimens were irradiated

by doses of 0, 66 and 99 kGy. There was an improvement in some micromechanical

properties of the surface layer of glass-filled PP. The improvement/deterioration of

micromechanical properties of surface layer of glass-filled PP measured by the instrumented

microhardness test is the content of this experimental study.

Acknowledgments – This paper is supported by the internal grant of TBU in Zlin No. IGA/FT/2014/016 funded from the resources of specific university research and by the European Regional Development Fund under the project CEBIA-Tech No. CZ.1.05/2.1.00/03.0089 and Technology Agency of the Czech Republic as a part of the project called TA03010724 AV and EV LED luminaire with a higher degree of protection.

References

1.Manas D., Manas M., Stanek M., Danek M.: Arch. Mater. Sci. Eng., 32 (2), pp. 69-76, (2008). 2. Uzuna O.;Kölemena U.; Çelebi S.; Güçlü N.: Journal of the European Ceramic Society 25, 969–977, (2005)

48

ESTIMATION OF LOCAL PLASTIC DEFORMATION IN CUTTING ZONE DURING

TURNING

MAROŠ MARTINKOVIČ, PETER POKORNÝ Slovak University of Technology in Bratislava, Faculty of Materials Science and Technology in Trnava, Pavlínska

16 91724 Trnava, Slovakia

Keywords: deformation, turning, cutting zone

Abstract

Local plastic deformation of workpieces during machining is affected by technological

conditions of the processes. Therefore it is needful to know detail structure changes of

plastic deformed material during machining – milling, turning, drilling etc. Metal cutting,

viewed as a plastic deformation process, is quite unique. It is localised, asymmetric

deformation which operates at very large strains and exceptionally high strain rates. Cutting

zone has three areas of intensive local plastic deformation: the primary area of plastic

deformation in shear plane, the secondary area of plastic deformation caused by friction of

chip to tool face and the tertiary area of plastic deformation caused by friction of tool to

work surface. The primary and secondary areas of plastic deformation has great influence to

technological process and vice versa, the tertiary area of plastic deformation has great

influence to quality of worked surface and local mechanical properties of surface layer of

workpiece. Local strain in structure can be estimated by measurement of deformation of

grains on metallographic cut. The turning piece was made of carbon steel CK45 (1.0503).

Method of cutting zone specimen obtaining by internal stress was used.

PLASTIC ZONE AROUND FATIGUE CRACK DETERMINED BY FEM AND

NANOINDENTATION TECHNIQUE

ALEŠ MATERNA, JAN ONDRÁČEK

Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague, Katedra materiálů, FJFI ČVUT v Praze, Trojanova 13, 120 00, Praha 2, Česká republika

Keywords: nanoindentation, finite element method, cyclic plastic zone,monotonic plastic zone

Abstract:

The nanoindentation is an effective technique for characterizing the hardness of small

volumes of material. It is supposed that intense cyclic deformation in a plastic zone ahead of

49

the fatigue crack changes the hardness and, therefore, the boundary of such small zone can

be characterized by the microhardness measurement. In this paper, numerical FEM

computation as well as grid nanoindentation was used to characterize the plastic zone size

of fatigue crack growing in Al-alloy D16CT1 and both methods are compared.

INFLUENCE OF NANOPARTICLE SIZE ON STRAIN AT THE CORE-SHELL

INTERFACE

ONDREJ MILKOVIČ, JANA MICHALIKOVÁ, JOZEF BEDNARČÍK

Keywords: high energy X-ray diffraction, nanoparticles, core-shell structure, microstrain

Abstract

This work deals with the strain at the core-shell interface of Fe nanoparticles. Series of Fe

nanoparticles with various mean diameters were prepared by precipitation in solid state in

binary Cu-Fe alloy. Further, nanoparticles were isolated by dissolution of Cu matrix. High-

energy X-ray diffraction (XRD) was used to probe structure of nanoparticles. XRD

measurements suggest presence of the core-shell structure, where core and shell of the

nanoparticles are formed of α-Fe and CuFe2O4 phase, respectively. Strains in core and shell

were estimated as a function of nanoparticles size by Williamson-Hall method.

SPONTANEOUS NANOSCALE PERIODIC STRIPES IN METALLIC AMORPHOUS

RIBBON

JOZEF MIŠKUF et al.

UEF SAV, Watsonova 47, 040 01 Košice, Slovakia

Keywords: amorphous metals, corrugations, nanosized dimples

Abstract

We analyzed the failure characteristics of the bulk metallic glass Co43Fe20Ta5.5B31.5 (at.%)

deformed in bending. The fracture surface morphology at the nanoscale level respects the

micromechanisms of the failure of the amorphous structure. The fracture surface consists of

a smooth mirror cleavage zone and a river pattern zone with nanosized dimples arranged in

50

lines respecting the periodic corrugation zones oriented perpendicular to the crack

propagation direction.

SURFACE LAYER MICRO-HARDNESS OF MODIFIED LDPE BY RADIATION CROSS-

LINKING AFTER TEMPERATURE LOAD

ALES MIZERA, MIROSLAV MANAS, DAVID MANAS, MARTIN OVSIK, MICHA STANEK, JAN NAVRATIL, MARTIN BEDNARIK

Tomas Bata University in Zlin, nam. T.G. Masaryka 5555, 76001 Zlin, Czech Republic

Keywords: Micro-hardness, Low density polyethylene (LDPE), Irradiation, Radiation cross-linking

Abstract Radiation processing of polymers is a well-established and economical commercial method

of precisely modifying the polymer properties. The industrial applications of the radiation

processing of plastics and composites include polymerization, cross-linking, degradation and

grafting. Radiation processing mainly involves the use of either electron beams from

electron accelerators or gamma radiation from Cobalt-60 sources. The presented article

deals with the research of surface layer´s micro-mechanical properties of modified LDPE by

radiation cross-linking after temperature load. These micro-mechanical properties were

measured by the DSI (Depth Sensing Indentation) method on samples which were non-

irradiated and irradiated by different doses of the β – radiation and then were temperature

loaded. The purpose of the article is to consider to what extent the irradiation process

influences the resulting micro-mechanical properties measured by the DSI method. The LDPE

tested showed significant changes of indentation hardness and modulus after temperature

load

51

SURFACE PROPERTIES OF HDPE/HDPEX BLENDS

JAN NAVRATIL, MIROSLAV MANAS, MICHAL STANEK, DAVID MANAS, MARTIN BEDNARIK

AND ALES MIZERA

Tomas Bata University in Zlin, nam. T.G. Masaryka 5555, 76001 Zlin, Czech Republic

Keywords: recycling, hardness, micro-indentation hardness, irradiation, modification, HDPE. Abstract Advantageous properties of radiation crosslinked polymer materials are well known as well

as the fact that they cannot be remelted repeatedly. Growing usage of radiation crosslinked

polymers will therefore raise a question of their further disposal. The proposed solution is to

use such modified materials as a filler into non-modified ones. This study deals with

utilization of recycled irradiated high-density polyethylene (rHDPEx) which was blended with

non-modified high-density polyethylene (HDPE). Two blends were tested – HDPE

granules/rHDPEx grit and HDPE granules/rHDPEx powder in three concentrations from 10 to

60 %. Influence of the filler on hardness and micro-indentation hardness was investigated.

Results show that both, hardness and micro-indentation hardness slightly decrease with

increasing amount of the filling.

INFLUENCE OF HYDROGEN CONTENT ON MICROSTRUCTURE AND

MECHANICAL PROPERTIES OF Zr1Nb FUEL CLADDING AFTER HIGH-

TEMPERATURE OXIDATION

M. NÉGYESI1, O. BLÁHOVÁ2, J. BURDA3, J. ADÁMEK4, J. KABÁTOVÁ1, F. MANOCH1, V. ROZKOŠNÝ1, V. VRTÍLKOVÁ1

1 UJP PRAHA a.s., Nad Kamínkou 1345, 156 10 Praha - Zbraslav, Czech Republic

2 New Technologies Research Centre, University of West Bohemia, Univerzitní 8, 306 14 Plzeň, Czech Republic

3 NRI Rez plc, Husinec-Řež 130, 250 68 Řež, Czech Republic

4 Department of Materials, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in

Prague, Trojanova 13, 120 00 Praha 2, Czech Republic

Keywords: fuel cladding, Zr1Nb, oxidation, hydrogen, mechanical properties Abstract The microstructure evolution inside fuel claddings upon the Loss of Coolant Accident is of

significant importance since the fuel cladding integrity depends strongly on the

52

microstructure. Hydrogen, which can be absorbed by the fuel cladding during normal

operating conditions or upon the accident as well, influences the microstructure and causes

hydrides precipitation during the cooling-down process. It may consequently affect the

residual mechanical properties. The aim of this study is to investigate the influence of

hydrogen on the microstructure and mechanical properties of Zr1Nb fuel cladding after high-

temperature oxidation. As-received or pre-hydrided materials were tested. The influence of

different cooling rates was examined as well. The microstructure was observed employing

light microscope. Oxygen distribution was measured using X-ray microanalysis. Local

mechanical properties were determined by the microhardness and nanohardness

measurements. Ring Compression Testing was conducted to obtain the macroscopic

mechanical properties. Fractography analysis followed after the Ring Compression Tests. The

experimental results confirmed that hydrogen as well as the cooling rate substantially

influences the microstructure and affect both local and macroscopic mechanical properties.

LOCAL MECHANICAL CHARACTERIZATION OF METAL FOAMS BY

NANOINDENTATION

JIŘÍ NĚMEČEK, VLASTIMIL KRÁLÍK

Technical University in Prague, Thákurova 7, Praha 6, Czech Republic

Keywords: metal foam, aluminium alloy, Alporas, Aluhab, nanoindentation, deconvolution, micromechanics Abstract

This paper deals with the study of microstructure and micromechanical properties of a solid

phase of two different commercially available aluminium-based foams (Alporas and Aluhab).

Since none of the materials is available in a bulk and standard mechanical testing on macro-

scale is not possible the materials need to be tested at micro-scale. Metal foams are formed

with large pores and very thin pore walls. Small wall dimensions and the manufacturing

process produce a specific heterogeneous microstructure whose properties can be

successfully characterized with nanoindentation. To obtain both elastic and plastic

properties quasi-static indentation was performed for two different indenter geometries

(Berkovich and spherical tip).

53

The material phase properties were analyzed with grid indentation method and

micromechanics was applied to obtain effective elastic wall properties from the

experimental nanoindentation. Results of elastic moduli were monitored in several distant

locations on the aluminium foam cell walls. Elastic parameters were obtained on a statistical

set of nanoindentation results from which different mechanical phases were separated by

the deconvolution algorithm. Effective elastic properties of a cell wall of both materials were

evaluated by the Mori-Tanaka elastic homogenization.

In addition to elastic properties, effective inelastic properties of tiny aluminium foam cell

walls were identified with spherical indentation. Constitutive parameters related to plastic

material with linear isotropic hardening, the yield point and tangent modulus, were directly

deduced from the load–depth curves of spherical indentation tests using formulations of the

representative strain and stress introduced by Tabor. The results were mutually compared.

FEA OF THE CORTICAL BONE THICKNESS EFFECT ON THE STRESS

DISTRIBUTION IN DENTAL IMPLANTS

DUŠAN NÉMETHa, FRANTIŠEK LOFAJa , JÁN KUČERAb,

aInstitute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001, Košice

bSTONEK, s. r. o., Krivá 23, 040 01 Košice, Slovak republic

Keywords: thickness, stress, dental implant, FEM analysis, cortical bone Abstract

The stress distribution in cortical bone and dental implant has been modeled by finite

element method (FEM) using linear static analysis in the case of monocortical and bicortical

fixation of a real dental implant for three cortical bone thicknesses: 2 mm, 2.5 mm, 4 mm.

The analysis revealed that the highest stresses in the cortical bone and the implant after

three-axial loading 118 N are localised at the edge of the cortical bone around the implant

neck where bending moment is the highest. Thickness of the cortical bone and intraosseal

length of the implant significantly influence the maximum stresses. Linear increases of the

maximum stresses has been observed when the intraosseal length of the implant and

cortical bone thickness decreases.

Acknowledgments – This work was supported within the frame of the projects VEGA 2/0108/11, APVV-0520-10, and NnanoCEXmat II: ITMS No: 26220120035.

54

THE EFFECTS OF MODIFYING CONCRETE WITH NANOPARTICLES IN THE LIGHT

OF LITERATURE REPORTS

PAWEŁ NIEWIADOMSKI

Wroclaw University of Technology, Wybrzeże Stanisława Wyspiańskiego 27, 50-370 Wrocław, Poland

Keywords: concrete, nanoparticles, physical properties, mechanical properties, microstructure

Abstract

For about two decades now there has been a growing interest in nanoscale materials.

Recently the idea to use nanoparticles as a component in the production of concrete has

emerged. Attempts are made to use nano-SiO2, nano-TiO2, nano-Al2O3, nano-CuO, nano-

Fe2O3, nano- Cr2O3, etc., for this purpose. By modifying the composition of concrete with

nanoparticles it is hoped to obtain a material with improved physical and mechanical

properties in comparison with those of the concrete without nanoparticles. Such research is

conducted in many laboratories in the world. The results of this research, although not

complete, seem to be promising. They are, however, much dispersed. In connection with his

PhD dissertation the author has compiled and compared the results, critically analyzed them

and drawn conclusions from the analysis. The findings are to be presented in the announced

paper.

MICRO-INDENTATION TEST AND MORPHOLOGY OF ELECTRON BEAM

IRRADIATED HDPE

MARTIN OVSIK, DAVID MANAS, MICHAL STANEK, MIROSLAV MANAS, LENKA CHVATALOVA, ADAM SKROBAK

Tomas Bata Univerzity in Zlín , TGM 5555, 760 01 Zlin, Czech Republic

Keywords: Micro-hardness, micro-indentation test, polyethylene, cross-linking, β – radiation

Abstract

Cross-linking is a process in which polymer chains are associated through chemical bonds.

The cross-linking level can be adjusted by the irradiation dosage and often by means of a

cross-linking booster. The polymer additional cross-linking influences the surface nano and

55

micro layers in the way comparable to metals during the thermal and chemical-thermal

treatments.

The aim of this paper is to study the effect of ionizing radiation with different doses (33, 66

and 99 kGy), on micro-mechanical properties of polyethylene (HDPE) and compare these

results with those of non-irradiated samples. The study is carried out due to the ever-

growing employment of this type of polymer. Influence of the cross-linking by β – radiation

of the tested HDPE on micro-indentation test and morphology was investigated. Depth

sensing indentation test were performed and results compared. According to the measured

data tested material characteristics are significantly influenced by the dose of irradiation.

Micro-mechanical properties increased with increasing value of the dose of irradiation

material. The changes were examined and confirmed by X-ray diffraction.

EVALUATION OF MECHANICAL AND MICROSTRUCTURAL PARAMETERS OF

MULTIPHASE MATERIALS USING DRIFT DISTORTION CORRECTED SEM

IMAGING

VERONIKA PETRANOVA, PETR KOUDELKA, DANIEL KYTYR, TOMAS DOKTOR, JAROSLAV VALACH

Institute of Theoretical and Applied Mechanics AS CR, v.v.i., Prosecká 809/76, 190 00 Prague 9

Keywords: drift distortion, SEM, elastic properties, microstructure, digital image correlation

Abstract

Recently variety of optical methods including measurements of deformations at reduced

length scales have been widely used in experimental mechanics by employing computer

vision techniques on scanning electron microscopy (SEM) imaging. However such SEM based

analysis may produce results with low reliability and repeatability when image distortion

phenomenon is not taken into account. In contrast to imaging in visible spectrum

temporally-varying distortion (drift distortion) caused by positional errors of electron beam

during the scanning process occurs in SEM devices. This effect is always present in the data

from SEM and its magnitude depends on exposure time, magnification and conductivity of

the sample (where lower conductivity causes higher drift distortion).In this paper 2D digital

image correlation (DIC) based on Lucas-Kanade algorithm was used to assess drift distortion

characteristics of MIRA II LMU (TESCAN, CZ) SEM device during imaging of materials with

56

different conductivity and microstructural properties. Using the DIC technique deformations

in the micrographs were evaluated and tool for correction of positional errors was

developed. As shown on a set of selected multiphase mixtures this tool enables qualitative

backscattered electron (qBSE) analysis of mechanical properties and characterization of the

microstructure (e.g. measurement of grain sizes, etc.) independently on the material type

and imaging parameters including exposure time.

COMPARISON OF THE RESULTS OF CREEP AND MICRO - INDENTATION CREEP

TO IRRADIATED HDPE

MARTIN REZNICEK, DAVID MANAS, MICHAL STANEK, ADAM SKROBAK, VOJTECH SENKERIK, PETR KRATKY

Tomas Bata, University in Zlín, nám. T. G. Masaryka, Zlín, Czech Republic

Keywords:micro-indentation, comparison, irradiated , creep, HDPE

Abstract

Polymeric materials are very often used material in many applications. These materials

however have a number of negative properties, which in practice cause many problems.

These problems can then lead to limited availability of products or their premature

destruction. One of the options to avoid these unpleasant structural problems is the right

choice of material. This option is hard and is dependent on a number of factors, the mutual

combinations looking for the most suitable material. Choosing the right material to use to

facilitate a number of tests that are in the research and development of the material is

performed. Groups of tests on different materials together often very closely linked and they

are mutually substitutable. This article is focus comparison of two tests that are performed

with different methods and their conclusion could lead to a discount. Testing materials is

used herein Radiation cross linking of HDPE, which is measured to creep at room

temperature and compared with the results micro-indentation creep. The paper focuses on

the comparison, whether this dependence will be visible when the creep test and micro-

indentation.

57

MECHANICAL FRACTURE PROPERTIES OF CEMENT MORTARS WITH

ADMIXTURES IN RELATION TO THEIR MICROSTRUCTURE

PAVLA ROVNANÍKOVÁ, HANA ŠIMONOVÁ, ZBYNĚK KERŠNER, PAVEL SCHMID

Brno University of Technology, Faculty of Civil Engineering, Veveří 331/95, 602 00 Brno, Czech Republic

Keywords: hardened cement mortar, admixture, fracture toughness, fracture energy, microstructure Abstract

The paper is focused to evaluation of mechanical fracture properties of hardened cement

mortars with a partial replacement of Portland cement reactive admixtures in relation to the

microstructure through the size and content of pores. In mortars cement was partially

replaced by admixtures that contain different amounts of amorphous SiO2. Three-point

bending test on beams with a central edge notch were performed. Mechanical fracture

properties of mentioned cement-based composites covered elasticity modulus, effective

fracture toughness and specific fracture energy.

THE BEHAVIOUR OF RECYCLED MATERIAL WITH PARTICLES OF VARIOUS SIZES

OF POLYAMIDE 6 TO MICRO HARDNESS

VOJTECH SENKERIK, MICHAL STANEK, MIROSLAV MANAS, DAVID MANAS, ADAM SKROBAK, AND JAN NAVRATIL

Tomas Bata, University in Zlín, nám. T. G. Masaryka, Zlín, Czech Republic

Keywords: recycled material, particle size, sieving, polymer, polyamide

Abstract

Every manufacture of any plastic parts produces some waste, such as defective injects or

cold runner system from injection molding technology. This waste can be directly used

several times. But when size of this material is reduced, particles of different sizes are made.

From large particles similar to the original granulate material, to dust particles. This size

variation can cause problems during subsequent processing. These particles of different size

have distinct melting rate. That can cause an inhomogeneity of a melt and diverse structure

of solidified polymer. This research paper studies the influence of the particle size of

recycled polymeric material on the micro harness properties of semi-crystalline polyamide 6

at room temperature.

58

MEASURING THE MICROMECHANICAL PROPERTIES OF RUBBER TESTING

SAMPLES

ADAM SKROBAK, MICHAL STANEK, DAVID MANAS, MARTIN OVSIK, VOJTECH SENKERIK, MARTIN REZNICEK

Tomas Bata, University in Zlín, nám. T. G. Masaryka, Zlín, Czech Republic

Keywords: Injection molding, compression molding, micromechanical properties, rubber

samples, DSI - Depth Sensing Indentation

Abstract When producing rubber products it is necessary to watch and check the mechanical

properties whether it be the properties of the processed material, i.e. the rubber compound,

or properties of the product itself. This control aims primarily on how the mechanical

properties are influenced by the preparation of the rubber-processing compounds itself, or

the change of technological conditions, e.g. the curing time, the curing temperature etc.

However, it does not deal with the impact of changing the whole production technology.

One of the very productive technologies, which is coming forth, is the production by

injection. Control of the mechanical properties of rubber products produced by injection

molding is mostly performed on testing samples produced in another way, i.e. cutting off a

compression molded plate. The aim of this article is to demonstrate and asses to what

extent there is an impact on the micromechanical properties of a standardized testing

sample made of rubber compound based on EPDM and produced by injection molding in

comparison with a sample produced by classic preparation (cutting off a compression

molded plate). Measurement of the properties was carried out according to the

instrumented test (DSI), in compliance with ISO 14577 on the measuring device micro-

combi-tester.

MODELLING AND ANALYSIS OF REINFORCED CONCRETE BEAMS

OLDRICH SUCHARDA, JIRI BROZOVSKY

VSB - Technical University Ostrava, Ludvika Podeste 1875/17, 708 33 Ostrava – Poruba, Czech Republic

Keywords: Concrete; Beam; Bearing Capacity; Reinforced; Finite Analysis; Non-linear

Analysis; Fracture-plastic.

59

Abstract

This paper discusses the fracture-plastic material models for reinforced concrete and use of

this model for modelling of reinforced concrete beams. Load-displacement relations and

bearing capacity of reinforced concrete beams will be evaluated. Series experiments - the

beam and data from completed experiments - have been chosen for the numerical

modelling. In case of the experiments - reinforced concrete beams, stochastic modelling

based on LHS (Latin Hypercube Sampling) will be carried out in order to estimate the total

bearing capacity. The software used for the fracture-plastic model for reinforced concrete is

ATENA.

References

[1] CEB - FIP Model Code 1990: Design Code. by Comite Euro-International du Beton, Thomas Telford, 1993. ISBN 978-0727716965.

[2] W., F. Chen: Plasticity in Reinforced Concrete. Mc. New YorkGraw Hill, 1982. [3] Computer program ATENA 2D: Theory Manual. Praha: Červenka Consulting, (2000) [4] Computer Pragram FReET (Computer Pragram for Statistical, Sensitivity and Probabilistic

Analysis): Theory Manual. Brno, 2002. [5] J. Červenka, V. K. Papanikolaou: Three dimensional combined fracture-plastic material

model for concrete. Int. J. Plasticity, Vol. 24, (2008), no. 12, p. 2192-2220. ISSN 0749-6419.

[6] G. Rombach: Anwendung der Finite-Elemente-Methode im Betonbau. 2.Auflage. Berlin: Ernst & Sohn, (2007). ISBN 978-3-433-01701-2.

[7] O. Sucharda, J. Brožovský. Bearing capacity analysis of reinforced concrete beams. International Journal of Mechanics., Vol. 7, 2013, n. 3, pp. 192-200 (9 p).

UTILIZATION OF ACCOUSTIC EMISSIONS IN SCRATCH TEST EVALUATION

JAN TOMASTIKa, RADIM CTVRTLIKa, PETR BOHACb, MARTIN DRÁB c,d, VÁCLAV KOULAd, KAREL CVRKd, LUBOMÍR JASTRABÍKb

a)Joint Laboratory of Optics of Palacky University and Institute of Physics ASCR, v.v.i.,

tř. 17.listopadu 50a, 779 00 Olomouc b)

Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8 c)

Faculty of Nuclear Sciences and Physical Engineering, CTU Prague, Trojanova 13, 120 00 Praha 2 d)

ZD Rpety - Dakel, Ohrobecká 408/3, 142 00 Praha 4

Keywords: Acoustic emission, Scratch test, Thin films Abstract

The scratch test is a well established instrumental method for assessment of the cohesive-

adhesive parameters of various film-substrate systems. Test consists of pulling the diamond

indenter over the sample surface under an increasing normal force. Using microscopic

60

analysis of residual scratch and indenter depth record, the onsets of typical film failure

modes can be observed. However, this approach can be insufficient for detection of the very

first film-to-substrate adhesion failures, especially for opaque layers. To overcome this

difficulty an AE can be employed.

During scratching procedure film is loaded and deformed. This generates acoustic waves of

specific frequencies, which could be detected using the appropriate sensor. The detection

system of acoustic emission developed in our laboratory is based on a special holder and

continuous recording during the whole scratch test. The high resolution stems from 2 MHz

sampling rate. The sophisticated software allows thorough post process analysis of recorded

acoustic emission signal. Dynamics of individual events can be observed on microsecond

scale, as well as frequency analysis of the processes.

The demonstration of the acoustic emission probe detection capability is performed on the

model layers. Comparison of the acoustic emission record to residual scratch image and

indenter depth-change record shows a quality detection capability of the method. Analysis

of failure mode dynamics at the appropriate time scale is outlined.

Acknowledgments - This work was supported by the projects CZ.1.05/2.1.00/03.0058 of the MSMT CR, TA 03010743 of the TACR, grant P108/12/1941 of the GACR and internal grant of Palacky University no. PrF_201405.

INFLUENCE OF CARBON NANOTUBES ON THE MECHANICAL PROPERTIES AND

MORPHOLOGY OF THE DIFFERENT THERMOPLASTIC POLYMER MATRICES

JAN VÁCHA

Technical univerzity of Liberec, KSP, Studentská 2, Liberec, Czech Republic

Keywords: Carbon nanotubes, nanocomposites, morfology, mechanical properties

Abstract This paper examines the mechanical properties of the composites of thermoplastic polymer

matrix with carbon nanotubes. As the basic polymer matrices are used polypropylene (PP),

acrylonitrile butadiene styrene (ABS), polycarbonate (PC), to which were added to the

nanoparticles in a given percentage by weight in the form of nanotubes. Composites were

injected into the Arburg injection molding machine. For evaluation the mechanical

properties were measured by tensile test, hardness test. These tests are compared with

61

polymeric materials without added nanofiller. In conclusion is evaluated and compared

influence on the mechanical properties of polymer matrices with carbon nanotubes and

without fillers.

LOCAL MECHANICAL PROPERTIES OF HIGHLY POROUS SI3N4 FOR TRABECULAR

BONE REPLACEMENT

ZUZANA PRAMUKOVÁa, MONIKA KAŠIAROVÁa, MAGDALÉNA PRECNEROVÁb, MIROSLAV

HNATKOb, PAVOL ŠAJGALÍKb

a Slovak Academy of Sciences, Institute of Materials Research, Watsonova 47, Košice, SR b

Slovak Academy of Sciences, Institute of Inorganic Chemistry, Dúbravská cesta 9, SR

Keywords: Silicon nitride, Trabecular bone, Hardness, Young’s modulus

Abstract

Local mechanical properties of highly porous silicon nitride potentionally utilized as

trabecular bone replacement were studied. The applications of porous ceramics are

extensive due to very favorable combination of their properties. The study deals with the

development of highly porous undegradable ceramics as potential substitution for bone

tissue engineering. These materials were produced via replication method with

polyurethane foam as pore-forming agent to achieve similar porous structure to trabecular

bone. Prepared porous ceramics had a bimodal and anisotropic pore structure, with macro-

pores larger than 100 µm in diameter, and with micro-pores smaller than 50 µm in diameter,

which are necessarry for tissue ingrowths, cell adhesion, adsorption of biologic metabolites

and nutrition delivery.

This work is focused on the determination of local mechanical properties, such as Young’s

modulus and hardness of individual struts in a highly porous structures. Measurements were

carried out using nanoindentation technique in order to determine mechanical properties of

the matrix. The microstructure, porosity and local mechanical properties of experimental

materials were evaluated and compared with the human trabecular bone.

62

FIG. 1 MICROSTRUCTURE OF THE HUMAN TRABECULAR BONE (A) AND POROUS SI3N4 (B)

Acknowledgement - this work was realized within the frame of the projects APVV-0500-10

and COST Action MP1005, which are supported by the Operational Program “Research and

Development” financed through European Regional Development Fund.

HARDNESS OF SINTERED FE-MN SAMPLES WITH MICROGRADIENT

STRUCTURE

A. ZELEŇÁK, M. KUPKOVÁ

IMR SAS Košice, Watsonova 47, 040 01, Slovakia

Keywords: microhardness, iron powder, manganese powder, microstructure Abstract

Iron powder and mixed iron and manganese powder were compressed into cylindrical form

by 600 MPa press. Compacts were then sintered under pre-defined conditions, i.e. at 1120°C

for 1 hour in the reduction atmosphere 90%N2-10%H2. Investigated samples contained

25wt.% Mn. Mechanical properties have been investigated by microhardness measuring

method using Microhardness tester TUKON 1102. Constant loading was 10g per 10 seconds.

For each investigated sample, 300 indents were made. The differences in measured values of

microhardness reflect a clear effect of microgradient of structure on mechanical properties

of investigated systems.

a b

63

MECHANICAL AND TRIBOLOGICAL PROPERTIES OF HIPIMS AND HITUS W-C

BASED COATINGS

PETRA HVIŠČOVÁ1, LENKA KVETKOVÁ1, FRANTIŠEK LOFAJ1,2, MICHAL NOVÁK1,2, RUDOLF PODOBA1, MILAN FERDINADY1

1 Institute of Materials Research of Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovakia 2 Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava,

Bottova 25, 916 24 Trnava, Slovakia

Keywords: HiPIMS, HiTUS, hardness, coefficient of friction, microstructure Abstract

Several series of W-C based coatings were deposited by High Power Impulse Magnetron

sputtering (HiPIMS) and High Target Utilisation sputtering (HiTUS). Under different

conditions to investigate the effect of the content of acetylene, power density, frequency

and RF bias, respectively. The nanohardness was used to op�mize deposi�on condi�ons of

the studied coa�ngs for each technology. The maximum hardness of HiTUS W-C coa�ngs

was ̴ 32 GPa whereas only ̴ 20 GPa has been achieved in HiPIMS coatings made with the

studied range of power densities and duty cycle of 3 %. The hardness of the coatings was

also correlated with their elemental composition and tribological behavior.

SCRATCH RESISTANCE OF THE SI3N4-GRAPHENE NANOPLATELETS

COMPOSITES

M. KAŠIAROVÁ1, M. MICHÁLKOVÁ2, J. DUSZA1, P. ŠAJGALÍK2

1 Institute of Materials Research, Slovak Academy of Sciences, Košice, Slovak Republic

2 Institute of Inorganic Chemistry, Slovak Academy of Sciences, Bratislava, Slovak Republic

Abstract

The scratch resistance of the silicon nitride with the addition of graphene platelets (GNPs)

has been studied. Composites Si3N4-1wt.% GNPs with five different combinations of sintering

additives were prepared by hot-press sintering. The work examined the influence of the

different microstructure evaluation caused by the sintering additives on the scratchability of

materials. The basic mechanical properties such as hardness and indentation fracture

toughness were measured and the propagation of cracks were studied in order to

understand the scratchability of composites Si3N4-GNPs. The effect of the addition of

graphene platelets on the crack evolution and propagation during scratch test were

evaluated and explained.

Acknowledgement - The authors gratefully acknowledge the financial support of project APVV 0161-11.