Developing Empirical Relationships to Predict Porosity and Microhardness of Atmospheric Plasma-Sprayed Alumina Coatings on AZ31B Magnesium Alloy

AbstractPlasma-sprayed alumina coatings find wide-ranging applications by virtue of their inherent wear and corrosion resistance and attractive dielectric and diffusion barrier properties. In this work, empirical relationships were developed to predict the porosity and microhardness of alumina coatings by incorporating independently controllable atmospheric plasma-sprayed operational parameters (input power, stand-off distance and powder feed rate) using response surface methodology (RSM). A central composite rotatable design with three factors and five levels was chosen to minimize the number of experimental conditions. Within the scope of the design space, the input power and the stand-off distance appeared to be the most significant two parameters affecting the responses among the three investigated process parameters. A linear regression relationship was also established between porosity and microhardness of the alumina coatings.