AM60B镁合金微弧氧化膜的电化学腐蚀行为

在硅酸盐体系中对AM60B镁合金进行微弧氧化处理,采用循环伏安(CV)法、Tafel极化曲线和电化学阻抗谱(EIS)研究膜层在3.5% NaCl介质中的电化学腐蚀行为.结果表明:AM60B镁合金经微弧氧化处理后,膜层耐蚀性得以显著提高.相比低电压下的膜层,高电压下获得膜层微孔略大,但微孔数量明显较少,厚度显著增加,这使得膜层在整个腐蚀过程中呈现了极强的电阻性和优异的耐蚀能力,甚至测试结束时腐蚀介质仍未渗透至膜基面,而低电压下处理得到的膜层,腐蚀介质已渗透至膜基面且侵蚀了基体.

Electrochemical corrosion behavior of micro-arc oxide film on AM60B magnesium alloy

AM60B magnesium alloy was treated by means of micro-arc oxidation (MAO) in silicate system. The corrosion behavior of the film coated in 3.5 % NaCl medium was studied by using cyclic voltammetry (CV), Tafel polarization curve and electrochemical impedance spectroscopy (EIS). The result showed that the corrosion resistance of the film on AM60B magnesium alloy would be significantly improved after MAO treatment. Compared with the film coated under low voltage, the micro-pore size in the film coated under high voltage would be slightly larger, but the number of micropores would significantly reduce, and the thickness of the film would obviously increase, so that making the film exhibit extremely strong resistance and excellent corrosion resistance in entire corrosion process. Even at the end of the test, the corrosive medium would still not penetrate the coating into the interface between the film and the substrate. Nevertheless, when the film was coated under low voltage, the corrosive medium would already penetrate the film to erode the substrate.