Development of microarc oxidation process to improve corrosion resistance on AZ91HP magnesium alloy
(1.江西科技师范学院 江西省材料表面工程重点实验室, 南昌 3300132.中国科学院 金属研究所 材料环境腐蚀试验研究中心, 沈阳 1100153.中国科学院金属研究所 材料环境腐蚀试验研究中心, 沈阳 1100164.Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University,Nanchang 330013, China)
Abstract: A new anodizing process, which does not contain chromate but can improve the corrosion resistance of magnesium alloys significantly, was developed using a microarc power supply. Surface morphology was observed and the coating was compact and ceramic-like. In addition, the corrosion resistance of samples before and after anodization by the new process and a method in US Patent 5470664 was compared by potentiodymaic polarization curves, electrochemical impedance spectroscopy (EIS) and salt spray test. The results show that the anodization can improve the corrosion resistance of magnesium alloy. The samples obtained by the new process and the method mentioned in the US Patent 5470664 achieve 9 and 7 rates after 336 h salt spray test, respectively.
Key words: magnesium alloy; corrosion resistance; microarc oxidation