Research On Corrosion Resistance Of Oxidation Film And Micro-arc Oxidation Process Of AZ31 Magnesium Alloy

AZ31 alloy was treated by microarc-oxidation method in different electrolytes. The optimum formula of electrolyte was fixed on after lots of scree ning experiment and one of orthogonal tests. This electrolyte is consist of Na₂SiO₃(6g/L), glycerol(15mol/L), KF(14g/L) and NaOH(1g/L). A slippery oxidation film was created after microarc-oxidation by this electrolyte. The results indicate that the corrosion resistance of AZ31 alloy was improved compared with no treated AZ31 alloy. Then the effect of treatmentment time,current density and post treatment on the film performance were studied, the optimum processing parameters were found.The application of rare earth of Ce in surface modification of AZ31 magnesium alloy was studied by depositing rare-earth metal on the AZ31 magnesium alloy. Results indicate that the corrosion resistance improved. Base on the experiment, the effect of the technical parameter on the property was researched, and the best parameter was developed.The appearance, structure, composition and corrosion resistance of AZ31 magnesium alloy microarc oxidation film are analyzed by SEM, XRD and salt spray corrosion experimentation. The results indicate that the oxidation film is composed of MgO, MgAl₂O₄, Mg₂SiO₄ and amorphism phase. The growing fashion of the oxidation film is extrorse at the beginning. It begins to grow inflexed along with time extending. The oxidation film has double layers structure. The outer layer is a layer as loose and lacunaris, the endothecium is compact. The element of Ce enters into oxidation film straightly, then it affects the growth of oxidation film. The element of Ce appear the effect of improving forming oxidation film and reducing disfigurement of the oxidation film.