Predicting the immersion corrosion behaviour in NaCl solution of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy

摘要

The corrosion deterioration process of uncoated and plasma sprayed alumina coated AZ31B magnesium alloy, was investigated using immersion technique. The aim of the present work is to compare the corrosion behaviour of uncoated substrate and alumina plasma spray coatings on AZ31B magnesium alloy in NaCl environment at different pH values, chloride ion concentration and immersion time. Empirical relationship was established to predict the effect of immersion test parameters on corrosion rate. The corrosion products were examined by XRD, SEM/EDAX and X-ray mapping techniques. The results of immersion test in NaCl solution showed that the alumina coating exhibited a much better corrosion resistance than that of the bare Mg alloy.