On-Line Measurement of Plasma-Sprayed Ni-Particles during Impact on a Ti-Surface: Influence of Surface Oxidation
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The objective of this study was to analyze the impact of plasma-sprayed Ni5%Al particles on polished and grit-blasted Ti6Al4V samples under oxidized and nonoxidized conditions. For this purpose, measurements of thermal radiation and velocity of individual plasma-sprayed particles were carried out. From the thermal radiation at impact, splat diameter during flattening and temperature evolution during cooling were evaluated. Characteristic parameters related to the quality of contact between the splat and the substrate were retrieved. The flattening speed was introduced to characterize wetting, while the cooling rate was used to characterize solidification. The idea was to get a signature of particle impact for a given surface roughness and oxidation state by identifying parameters which strongly affect the splat behavior. Sieved Ni5%Al powder in a narrow range (+65 −75 μm) was sprayed on four sets of titanium alloy surfaces, consisting of polished and grit-blasted samples, one set had a nonoxidized surface and the other one was oxidized in an oven at 600 °C for two hours. Resulting splats after impact were characterized by scanning electron microscopy, the splats on oxidized surface showed pores in their core and detached fingers at the periphery. The cooling rate and flattening degree significantly increased on the oxidized smooth surface compared to the nonoxidized one. This trend was not found in grit-blasted surfaces, which implies that impact phenomena are different on grit-blasted surfaces than on smooth surfaces thus further work is needed.
Keywordscoating-substrate interaction plasma spray forming roughness effects splats cooling
The authors would like to gratefully acknowledge the kind assistance of P. Gougeon who helped in building-up the experimental setup and took part in many discussions and M. Ottosson for his help in construction of the computer program.
- 1.M. Fukumoto, S. Katoh, I. Okane 1995 Splat behavior of plasma sprayed particles on flat substrate surface. In: Akira Ohmori (Ed.) Thermal Spraying: Current Status and Future Trends. Kobe, Japan: High Temperature Society of Japan, pp. 353-358 May 22-26, 1995Google Scholar
- 8.M. Fukumoto, H. Nagai and T. Yasui, Influence of Surface Character Change of Substrate due to Heating on Flattening Behavior of Thermal Sprayed Particle, Proceedings of the 2006 International Thermal Spray Conference, 2006Google Scholar
- 9.J. Cedelle, M. Vardelle, P. Fauchais, Effect of Substrate Surface Topography and Temperature, on Millimeter and Micrometer Sized Splat Formation and on Thermal Contact Resistance, Proceedings of the 2006 International Thermal Spray Conference, 2006Google Scholar
- 10.A.G. McDonald, S. Chandra, M. Lamontagne, and C. Moreau, Photographing Impact of Plasma-Sprayed Particles on Metal Substrates, Proceedings of the 2006 International Thermal Spray Conference, 2006Google Scholar
- 15.K.C. Mills, Recommended values of thermo physical properties for selected commercial alloys, ASM International, 2002Google Scholar