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2190 |
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Tuesday, May 04, 2010, Hullet Room 11:20 AM Wear Protection 2 |
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The influence of particle temperature, particle velocity and coating surface temperature on the sliding wear performance HVOF sprayed TiO2-Cr2O3 coatings |
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Lutz-Michael Berger* / Fraunhofer Institute for Material and Beam Technology, Germany Richard Trache / Fraunhofer IWS, Germany Sabine Saaro/ Fraunhofer IWS, Germany Rogerio Lima/ National Research Council of Canada - IMI, Canada Basil Marple/ National Research Council of Canada - IMI, Canada |
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Experimental TiO2-10-20wt%Cr2O3 powders were deposited by HVOF spraying on low carbon steel substrates. During the spraying process the particle temperatures and velocities were mapped in the cross section of the spray jet at different spray distances. An additional spray parameter, the coating surface temperature, was monitored via an infra-red camera. The elastic modulus (E) and hardness (H) values of these coatings were measured via in-depth sensing indentation. All these parameters, microstructural characteristics (SEM and XRD) and results were correlated with the ball-on-disk sliding wear performance to better identify and understand the main mechanisms that lead to the coating optimization. It was observed that with increasing particle speed and temperature, as well as, higher coating surface temperature, the volume loss during sliding wear tests decreases. Surprisingly, slight variations of coating surface temperature produced measurable effects on the mechanical behaviour. Despite the fact the wear performance is usually correlated with coating hardness, it was identified that the sliding wear behaviour is better correlated with coating resilience, more specifically, with the H3/E2 ratio. Finally, the wear resistance of these coatings was compared to that of TiO2-10-20wt%Cr2O3 deposited by APS. The superior wear resistance of the HVOF coatings was evident. |