Preparation and characterization of the micro-arc oxidation composite coatings on magnesium alloys forautomobile

摘要

The magnesium alloys attract the light-weight manufacture due to its high strength to weight ratio, however the poor corrosion resistance limits the application in automobile industry.The Micro-arc CompositeCeramic(MCC) coatingson AZ91D magnesium alloys were prepared by Micro-arc Oxidation (MAO) and electrophoresis technologies.The microstructure, corrosion resistance, abrasion resistance,stone impact resistance and adhesion of MCC coatings were studied respectively.The crosssection morphologies showed that the outer organic coating was filled into the hole on surface of MAO coating, andit acted as a shelter against corrosive products.The copper-accelerated acetic acid salt spray Test, abrasion resistance test, stone impact resistance test, thermal shock resistance test and adhesion test were used to evaluate the protective characterization by the third testing organizationwhich approved by GM.The test results showed the composite coatings meet all the requirements.The MCC coating on Mg presents excellent properties, and it is a promising surface treatment technology on magnesium alloys for production vehicles.