« Workshop Nanocoatings », Liège, January 15, 2015

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« Workshop Nanocoatings », Liège, January 15, 2015

Introduction (1) – Interesting prospects • Use of nanoparticles in metal matrix composites

– For new functions e.g. self cleaning

– For enhanced properties e.g. better wear or corrosion resistance, electrical and thermophysical properties…

• New applications of metallic materials • … but there are some challenges…

– Development of innovative processing routes e.g. solid-state processes such as Friction Stir Processing

• … and phenomena that are specific to MMNCs

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Introduction (2) - Challenges

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Friction Stir Processing of Cu + nano-particles of Y2O3

• Nanoparticles have a strong tendency to agglomerate • Homogeneous distribution is of paramount importance!

[Avettand-Fenoël et al., 2014]

3 passes 9 passes

Dispersion is more homogeneous

Introduction (3)

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FSP of Mg + carbon nanotubes (CNTs)

• Nano-particles may also cause changes in the metallic matrix! E.g. by affecting nucleation of new grains during solidification/recrystallisation or by pinning the grain boundaries ⇒ Refinement of the microstructure

• Strong effect can be obtained for small amount of nanoparticles

[Mertens et al., ULg-UCL]

Base Material FSP (9 passes) Mg + nanotubes de C

Hardness (HV10) Grain size (µm)

FSP (9 passes) 58.9 ± 0.2 17.0 ± 4.8

Mg + CNTs composite 68.7 ± 0.5 3.8 ± 1.2

Outline

• Introduction – Metal Matrix Nano-Composites – Interesting prospects… – … and new challenges – Nano-particles may also cause changes in the metallic matrix!

• Enhanced properties for new applications – Corrosion resistance – Wear resistance – Physical and termophysical properties – Others

• Summary • Acknowledgements • References

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Improved corrosion resistance (1)

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Ni + SiC nano-particles coating produced by co-deposition • The nano-composite

coating exhibits better corrosion resistance in salt spray cabinet

• The nano-composite coating is more compact and provides a better surface coverage

[Lekka, 2005]

Ni Ni + SiC During co-deposition, surfactants must be used to favour a good dispersion of the nano-particles in the suspension

Improved corrosion resistance (2)

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NiCrMoNb alloy + nano Y2O3 deposited by laser cladding • A powder is projected onto a

substrate and melted in a laser beam ‒ Mixture of two different powders… ‒ … or a composite powder

• Functionally

graded coatings

Lower current density at high potential

[Pér

ez, 2

012]

[Gu,

201

4]

Outline

• Introduction – Metal Matrix Nano-Composites – Interesting prospects… – … and new challenges – Nano-particles may also cause changes in the metallic matrix!

• Enhanced properties for new applications – Corrosion resistance – Wear resistance – Physical and termophysical properties – Others

• Summary • Acknowledgements • References

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Improved wear resistance (1)

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Ni + SiC coating produced by co-deposition

• The nano-composite coating exhibits better wear resistance compared to pure Ni and also to the micro-composite coating

• This effect is even stronger at high temperature

• The amount of nano SiC in the coating is very low i.e. 0,18 wt%

• Grain refinement and loss of preferential crystallographic orientation in the Ni matrix of the nano-composite play an important role!

[Lekka, 2012]

Room Temperature

300°C

Improved wear resistance (2)

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Ni + SiC coating produced by co-deposition

• The nano-composite coating exhibits better wear and scratch resistance compared to the micro-composite coating

• The micro-composite coating exhibits a higher surface roughness than the nano-coating

• Micro-particles may be chipped away from the coating and then contribute to accelerate wear [Narasimman, 2012]

Nano SiC

Micro SiC

Improved wear resistance (3)

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Ni + nano ZrO2 coating deposited by plasma spraying

• A good dispersion of the nano-particles is essential to improve wear performances

• Nano-particles clusters tend to act similarly to micro-particles

[Fernandes, 2013]

Mixture of 2 powders

One composite powder

Outline

• Introduction – Metal Matrix Nano-Composites – Interesting prospects… – … and new challenges – Nano-particles may also cause changes in the metallic matrix!

• Enhanced properties for new applications – Corrosion resistance – Wear resistance – Physical and termophysical properties – Others

• Summary • Acknowledgements • References

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Physical properties (1) - Electrical resistivity

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Cu + CNTs coating produced by co-deposition

• Current trends for miniaturisation in electronic devices ⇒ Need for Cu-based composite coatings with enhanced electrical conductivity / minimised electrical resistivity

• Carbon nanotubes appear very promising due to their high axial conductivity

• Resistivity of pure Cu: 1,89 µΩcm [Manu, 2013]

Conditions Percentage of CNTs (mass%)

Electrical resistivity (µΩcm)

Quiescent 1,2 2,11

Agitated 1,8 1,91

Variations in the morphology and porosity of the coatings

Physical properties (2) - Electrical conductivity

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Cu or Bronze + CNTs composites • Cu or bronze + CNTs

composites are produced by mechanical alloying + sintering

• Electrical conductivity of pure Cu is decreased by the addition of CNTs...

• ... but the electrical conductivity of bronze is increased

• Possibility to reach a good compromise between electrical and mechanical properties

[Uddin, 2010]

Physical properties (3) - Thermal expansion

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Cu + Al2O3 nanoparticles (in-situ synthesis) • Materials for heat sink

applications require the combination of a low CTE and of a high thermal conductivity

• Addition of Al2O3 nanoparticles allows decreasing the CTE

• But this comes at the expense of the thermal conductivity!

[Fathy, 2013]

At Room Temperature

Physical properties (4) - Thermal conductivity

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Cu + Y2O3 nanoparticles (FSP)

• A better compromise between a low CTE and a high thermal conductivity could be obtained by decreasing the volume fraction of nanoparticles (~0,7 vol.%)

[Shabadi, 2015]

Outline

• Introduction – Metal Matrix Nano-Composites – Interesting prospects… – … and new challenges – Nano-particles may also cause changes in the metallic matrix!

• Enhanced properties for new applications – Corrosion resistance – Wear resistance – Physical and termophysical properties – Others

• Summary • Acknowledgements • References

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"Self cleaning"

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Ni + TiO2 nanoparticles (codeposition) • Under UV irradiation,

TiO2 may give rise to the photocatalytic degradation of adsorbed pollutants

• Efficiency of this "self cleaning" effect depends − on the volume

fraction of TiO2 − on the texture in the

Ni matrix of the composite coating

[Spanou, 2013]

Degradation of Methyl Orange

Outline

• Introduction – Metal Matrix Nano-Composites – Interesting prospects… – … and new challenges – Nano-particles may also cause changes in the metallic matrix!

• Enhanced properties for new applications – Corrosion resistance – Wear resistance – Physical and termophysical properties – Others

• Summary • Acknowledgements • References

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Summary Metal Matrix Nanocomposite Coatings open very interesting prospects due to enhanced properties • Improved corrosion resistance in aggressive environments for

applications in chemistry, energy... • Enhanced wear behaviour for use in a wide range of

engineering components submitted to severe tribological conditions

• Better physical and thermophysical properties for applications e.g. in electronics

• New functionalities e.g. "self cleaning" for use in building, automotive industry...

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Acknowledgements • The MMS unit (ULg) and particularly H.M. Montrieux et S. Salieri • Sirris: J. Halleux et D. Garray • UCL: A. Simar and F. Delannay, along with the LAFAB team • For their financial support

– The Walloon Region (Winnomat Program) – The Interuniversity Attraction Pole Program, belgian office for scientific

policy, contract IAP7/21 “INTEMATE” – The European Development Funds and the Walloon Region (Belgium),

Project FEDER TipTopLam

• Thank you for your attention!

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References • M.-N.Avettand-Fenoël et al., Mater. Des., 60 (2014), 343 • A.Fathy and O.El-Kady, Mater. Des., 46 (2013), 355 • F.Fernandes et al., Wear, 303 (2013), 591 • D.Gu et al., Metall. Mater. Trans. A, 46 (2014), 464 • M.Lekka et al., Electrochim. Acta, 50 (2005), 4551 • M.Lekka et al., Surf. Coat. Technol., 206 (2012), 3658 • R.Manu and S.Priya, Appl. Surf. Sci., 284 (2013), 270 • P.Narasimman et al., Wear, 292-293 (2012), 197 • A.T.Pérez et al., Mater. Sci. Forum, 706-709 (2012), 2552 • R.Shabadi et al., Mater. Des., 65 (2015), 869 • S.Spanou et al., Electrochim. Acta, 105 (2013), 324 • S.M.Uddin et al., Comp. Sci. Technol., 70 (2010), 2253

Publications by ULg-MMS are available on http://orbi.ulg.ac.be/ Website ULg-MMS: http://www.metaux.ulg.ac.be/

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