Suspension High Velocity Oxy-Fuel (SHVOF)-Sprayed Alumina Coatings: Microstructure, Nanoindentation and Wear

Murray, J. W.; Ang, A. S. M.; Pala, Z.; Shaw, E. C.; Hussain, T.

Abstract

© 2016, ASM International. Suspension high velocity oxy-fuel spraying can be used to produce thermally sprayed coatings from powdered feedstocks too small to be processed by mechanical feeders, allowing formation of nanostructured coatings with improved density and mechanical properties. Here, alumina coatings were produced from submicron-sized feedstock in aqueous suspension, using two flame combustion parameters yielding contrasting microstructures. Both coatings were tested in dry sliding wear conditions with an alumina counterbody. The coating processed with high combustion power of 101kW contained 74wt.% amorphous phase and 26wt.% crystalline phase (95wt.% gamma and 3wt.% alpha alumina), while the 72-kW coating contained lower 58 wt.% amorphous phase and 42 wt.% crystalline phases (73 wt.% was alpha and 26 wt.% gamma). The 101-kW coating had a dry sliding specific wear rate between 4 and 4.5×10−5mm3/Nm, 2 orders of magnitude higher than the 72-kW coating wear rate of 2-4.2×10−7mm3/Nm. A severe wear regime dominated by brittle fracture and grain pullout of the coating was responsible for the wear of the 101-kW coating, explained by mean fracture toughness three times lower than the 72-kW coating, owing to the almost complete absence of alpha alumina.

Citation

Murray, J. W., Ang, A. S. M., Pala, Z., Shaw, E. C., & Hussain, T. (2016). Suspension High Velocity Oxy-Fuel (SHVOF)-Sprayed Alumina Coatings: Microstructure, Nanoindentation and Wear. Journal of Thermal Spray Technology, 25(8), 1700-1710. https://doi.org/10.1007/s11666-016-0462-0

• Journal Article Type: Article
• Acceptance Date: Sep 19, 2016
• Online Publication Date: Oct 7, 2016
• Publication Date: Dec 1, 2016
• Deposit Date: Nov 24, 2016
• Publicly Available Date: Nov 24, 2016
• Journal: Journal of Thermal Spray Technology
• Print ISSN: 1059-9630
• Electronic ISSN: 1544-1016
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 25
• Issue: 8
• Pages: 1700-1710
• DOI: https://doi.org/10.1007/s11666-016-0462-0
• Keywords: SHVOF, HVSFS, alpha alumina, gamma alumina, Rietveld refinement, dry sliding wear
• Public URL: https://nottingham-repository.worktribe.com/output/824285
• Publisher URL: http://link.springer.com/article/10.1007%2Fs11666-016-0462-0
• Additional Information: The final publication is available at Springer via http://dx.doi.org/10.1007/s11666-016-0462-0.
• Contract Date: Nov 24, 2016