Alumina-silica hollow microspheres in

metallo-ceramic matrix composite

A. Shishkin1

V. Mironovs 1, V. Zemchenkov 1, A. Korjakins1, I. Hussainova 2

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1 Riga Technical University (Latvia)2Tallinn University of Technology (Estonia)

CellMat 2014Dresden 22. October 2014

Riga Technical University

Figure 1. Statistical data from Science Direct web directory (12.06.2014)

1. Introduction

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The research work was carried out in the frame of the Latvian Council of Science Project:

"Development of sustainable effective lightweight construction materials based on industrial

waste and local resources" (No. Z12.0412).

1. Introduction

Figure 2. Clay depositions in Latvia

1. Introduction

A cenosphere (CS) is a lightweight, inert, hollow

sphere filled with inert gas (CO2, N2), typically produced

as a byproduct of coal combustion at thermal

power plants. The color of cenospheres varies from gray

to almost white and their density is about 0.4–0.8

g/cm³, which gives them a great buoyancy.

Figure 3. CS crossection, SEM.

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Figure 4. Joining of two CS by clay (after firing at 1000°C)SEM image, X 2000 times magnification.

1. Introduction

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2. Materials and Methods

CS physical propertiesParticle size 50-100 µm Bulk density 0.38 ± 0.013 g·cm-3

Specific Gravity 0.70 g·cm-3

Volume fillingCoefficient 0.56%Hardness 5-7 (Moh's)Coeff. of thermalConductivity 0.01 W·m-1·KMelting point t° 1600 - 1650°C LTIK 8 x 10-6(°K) pH in water 6 - 7

CS Clay “Liepa” ±,%

SiO2 71.22 53.8 ± 0.5

Al2O3 14.58 40.7 ± 0.5

TiO2 0.65 -- ± 0.1

Fe2O3 (FeO as Fe2O3) 4.17 1.0 ± 0.1

CaO 0.37 1.4 ± 0.2

MgO 0.96 0.6 ± 0.2

Na2O 0.058 0.5 ± 0.01

K2O 3.21 0.4 ± 0.10

Losses of mass by heating, mass%

400°C (-H2O) 1.34 0.6 ± 0.1

1000°C (-CO2) 3.31 0.4 ± 0.1

Table 1. Chemical composition of CS andHomogenized red clay of Liepa (mass %)

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2. Materials and Methods

Figure 5. Sponge-like surfacestructure of Fe powder AHC 100.2950-130um(Hoganas AB, Sweeden)

Figure 6. CS – light microscopy.50-100 um(BIotecha Latvia, Latvia)

Figure 7. Metallo-ceramics sample production scheme.

Clay preparation, (drying, milling, screening <150 um)

Clay and Fe powder mixed and milled in disintegrator

Clay-Fe mixture mixed with CS, Water, additives.

Formation by pressing

Firing

2. Materials and Methods

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Figure 8. Disintegrator principals scheme.a) side cross section b) Particle trajectory during milling/mixing process

-1

-1

1

2

[min ]

[min ]

ω 12000 =

ω 12000

2. Materials and Methods

a) b)

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Figure 9. SEM images of obtained composite material with magnificationa) X 50, BSE mode, b) X 50, SE mode, c) X500 BSE mode.

.

a) b) c)

Properties

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Properties

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PropertiesUltrasonic testing

Figure 11. Ultrasonic testing test setup

Ultrasonic parametersSignals acquisition:Through transmission Applied frequencies: 500, 800 and 1600 kHzExcitation: short tone-burst, 140 V ptp Reception: 30 MHz sampling rate, 10-bit

Ultrasound velocity (speed of sound) CC = L / (T –Dt),Where:

L is acoustic base (diameter of specimen)T is pulse time-of-flightDt is delay time (transducers’ constant)

FS = A800/A1600, where

A800 and A1600 are normalizied integral amplitudesof ultrasonic pulses acquired during onemeasurment act

Time of flight T

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5. PropertiesUltrasonic testing

Figure 12. Ultrasonic test results. a) sound speed, b) frequency slope

2000

2500

3000

3500

4000

CME 4-6-0 CME 4-6-4 CME 5-5-0 CME 5-5-4

Ultrasound velocity. C, m/s

0.00

0.40

0.80

1.20

1.60

CME 4-6-0 CME 4-6-4 CME 5-5-0 CME 5-5-4

Frequency slope FS

a) b)

Clay-Fe-CS, vol. part

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5. PropertiesUltrasonic testing

Ultrasound velocity. C, m/s Frequency slope FS

2000

2500

3000

3500

4000

T 1050 T 1100 T 1150 T 1180

0.00

0.40

0.80

1.20

1.60

2.00

T 1050 T 1100 T 1150 T 1180

a) b)

Clay-Fe-CS, vol. part

Figure 13. Ultrasonic test results of Specimens group CME 5-5-4a) sound speed, b) frequency slope

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Properties

Figure 14. compressive strength (a) and specific gravity (b)

189

246

295

318

120 120

163

224

100

150

200

250

300

350

1040 1060 1080 1100 1120 1140 1160 1180 1200

σ, N

/mm

2

T, °C

CME 5-5-0

CME 5-5-4

4,684,77

4,834,92

3,68 3,72

3,84

4,08

3,0

3,5

4,0

4,5

5,0

1040 1060 1080 1100 1120 1140 1160 1180 1200

ρap

r, g

/cm

3

T, °C

CME 5-5-0

CME 5-5-4

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Conclusion

• Fe/cenosphere, with natural clay as binder, syntactic foam obtained via powder metallurgy route.• Noted, that compressive strength and specific gravity are increases in linear dependence in lac of CS, but exponential in case of using CS in composition.• CS using in composition gives significant – up to 75% Frequency slope and up to 10 % sound velocity.Sample of composite material with

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Thank you for your attention!