Special issue "Magnesium and magnesium alloys". Corrosion behavior of magnesium alloys with different surface treatments.

Abstract

The effect of surface treatment on the corrosion behavior of diecast magnesium alloy AZ 91D-F has been investigated by salt spraying test. It was found that the corrosion resistance of the alloy decreased in the following order of surface treatments: anodizing with sealing, chromating, anodizing without sealing, mechanical polishing and no treatment (ascast). In any case, both the weight loss and the estimated maximum corrosion depth increased linearly with increase in the duration of spray test. X-ray diffraction analysis revealed that corrosion products consisted mainly of Mg(OH)2 and NaCl, irrespective of surface treatments. Polarization characteristics in 5%NaCl aqueous solution, however, depend on the surface states and are correlated well with the order of corrosion resistance.