Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.