Review of Corrosion-Resistant Conversion Coatings for Magnesium and Its Alloys

The corrosion susceptibility of Mg and its alloys in humid and aqueous environments limits their widespread application. The performance of several conversion coating technologies is reviewed herein. In addition to the assessment of performance based on the literature to date, thermodynamic analysis has been used to compare coating processes. Ongoing research reveals that the search for appropriate conversion coatings to replace toxic Cr-based coatings continues. It is seen that the variability between coatings of the same technology was greater than the averages between coating technologies. Additionally, coating pretreatment also appears to be more significant than the choice of coating technology itself.