Effect of ceramics coating using sol-gel processing on corrosion resistance and age hardening of AZ80 magnesium alloy substrate

Extruded plates of AZ80 magnesium alloy were coated with CeO2 and/or MgO ceramics by sol-gel processing. We investigated the effects of heat treatment conditions, under which the ceramic thin film was formed, on the mechanical properties and corrosion resistance of the substrates. Single layer (CeO2 or MgO) and double layer (CeO2/MgO) ceramic thin films were successfully formed from precursor solution by the sol-gel processing under optimal heat treatment, in which the AZ80 original substrates were age-hardened. The corrosion resistance of AZ80 magnesium alloy substrates evaluated by the salt water immersion test was found to be improved by ceramic coating and microstructural change of the original substrate during coating process. The double layer ceramic coating was superior to the single layer coatings in terms of corrosion resistance. The acquisition of corrosion resistance in AZ80 magnesium alloy substrates could be applied simultaneously by sol-gel processing, while the substrates were age-hardened by the heat treatment.