Effect of plasma spray parameters on in-flight particle characteristics and in-situ alumina formation

In the present study, mechanically alloyed Al–12Si and SiO2 powder was deposited onto an aluminum substrate by atmospheric plasma spraying (APS) to obtain a hypereutectic Al–Si based in-situ alumina formed composite coating. The effect of process parameters (arc current, spray distance, nozzle type, oxygen gas support and substrate cooling) on in-flight particle characteristics (temperature and velocity) and in-situ alumina formation were investigated. It has been observed that while arc current and nozzle inner-diameter strongly affects the in-flight particle characteristics and in-situ alumina formation, the effect of oxygen gas support is insignificant. Also, the results show that the substrate cooling considerably hinders alumina formation.