Investigation into the formation of Ni splats plasma-sprayed on to mild steel and stainless steel substrates

The present study investigates the splat formation behaviour of Ni particles plasma sprayed onto AISI 1008 mild steel and 316 austenitic stainless steel substrates to draw a comparative analysis of splat formation on both surfaces. A range of analytical techniques were used to analyse the surface and cross-sectional characteristics of the splats formed on both substrates. Most of the splats observed on both of the substrates were halo type splats driven by Rayleigh–Taylor instabilities. A linear relationship was identified between the size of the central core of the splats and their outer ring of debris, which was distinct for each substrate. The diffusion profile, obtained through STEM-EDS analysis, revealed a higher degree of diffusion across the interface between splat and stainless steel substrate as compared to mild steel, suggesting a better bond efficiency for stainless steel. Cross-sectional observations, together with theoretical calculations, showed evidence of substrate melting as well as the presence of metallurgical bonds for both mild steel and stainless steel substrates.