Micro-porosity Formation on the Underside of Plasma Sprayed Nickel Splats: A Microstructural Study
The gas (micro) porosity formation in splats produced by atmospheric plasma spraying was microscopically studied through a new approach. The aim was to prove hydrogen content in plasma gas mixture propagates micro-porosity to the splat-substrate interface. Nickel powder was sprayed under argon plus 0, 7, 10, and 13 vol.% hydrogen as a secondary plasma gas on a stainless steel substrate, and the obtained microstructures of the underside splats were investigated by a scanning electron microscope. It was shown that by increasing hydrogen concentration in plasma gas mixture, more micro-pores formed in the microstructures, while pores content reached to a saturation level at higher hydrogen concentrations.
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