Effect of experimental parameters on the micro hardness of plasma sprayed alumina coatings on AZ31B magnesium alloy

Surface treatment of engineering materials has recently become important for serviceable engineering components. Many techniques such as thermal and thermo chemical surface treatments have been used to develop surface characteristics of materials. Hardness is the most important property, which influences considerably service life characteristics of coatings. In this investigation, alumina coatings were deposited by atmospheric plasma spray technique under different levels of power, stand-off distances and powder feed rates. Empirical relationship was developed to predict the micro hardness of alumina coatings by incorporating the plasma spray process parameters. The input power and the stand-off distance appeared to be the most significant two parameters affecting the hardness of the coating among the three investigated process parameters. Further, correlating the spray parameters with coating properties enables the identification of characteristics regime to achieve desired quality of coatings.