Effects of Rare Earth Metal Oxide Doping on Micromorphology and Corrosion Behavior of Hydroxyapatite-Graphene Oxide Composite Coating Fabriacted on AZ91 magnesium alloy

Hydroxyapatite (HA)-graphene oxide (GO) composite coatings reinforced with various rare earth (RE) metal oxide (La2O3 and Y2O3) of composite coatings are electrophoretic deposited on AZ91 magnesium alloy substrate. The effects of RE metal oxide on the composition, surface morphology and corrosion behavior of HA-GO composite coatings in the solution of 0.9 wt. % have been systemically investigated. According to the experimental results, HA-GO-Y2O3 composite coating had displayed superior performance of corrosion prevention in 0.9 wt. % NaCl solution. Considering the results of EIS, microstructures, the surface porosity and the RE metal oxide in the HA-GO composite coatings. Taking the roles of the formation of HA-GO-RE complexes in pores/cracks of HA-GO composite coatings at the composite coatings/ the Mg (OH) 2 film interface in the corrosion mediums into account, the precipitation of precipitated HA-GO-RE protective film is a reasonable explanation for the corrosion resistance of AZ91 Mg alloy. The experimental results manifested that the effects of the microstructures and porosity, the formation of HA-GO-RE complexes in pores/cracks and Cl- concentration in NaCl solutions on improving corrosion resistance of AZ91 Mg alloy exhibited obviously synergistic effects.