The effect of inner shrouded gases rate on the microstructure of ZrC coating applied by solid shrouded plasma spraying (SSPS) and compared to atmospheric plasma spraying (APS)

In this study, the effect of injection of argon and hydrogen shielding gases on the properties of ZrC coatings, applied by solid shield plasma spraying (SSPS) and comparison with APS method were investigated. The effect of type and rate of injected gases on the microstructure of the coating were investigated by studying the morphology of the particles in the Single-line scan-spray. Also, the microstructure and phases of the coatings along with their porosity and oxide content were evaluated. The results show that the coating applied by SSPS method and injection of internal hydrogen gas at a rate of 20 l/min leads to an increase in the amount of splats in the coating and a decrease of more than 50% in the amount of oxides and porosity in the microstructure compared to APS coating. The H2 gas is injected to solid shield burns with O2 that caused a reduction in the amount of oxides in SSPS coatings and increase the heat and temperature around the plasma jet and increase the amount of molten particles in the coatings.