AZ91D镁合金外加电场下自封孔微弧氧化膜层微观形貌及耐蚀性的研究

微弧氧化技术可以实现对金属表面的高耐蚀、耐磨等改性,传统微弧氧化所得陶瓷膜具有多孔结构,影响了其耐蚀性能及高温氧化性能。本文针对氧化膜多孔结构与腐蚀性能之间的关系开展基础研究。采用外加电场微弧氧化技术实现自封闭孔结构,并研究了不同孔结构膜层的耐蚀性能；讨论了封孔过程中胶体运动-电位-孔结构表征之间的规律性关系,评价了自封孔后膜层腐蚀性能。主要研究结果表明：膜层中的多孔结构是腐蚀介质的通道,自封孔后耐蚀性能提高,此外,耐蚀性与孔隙率及封孔填充物的成分和形态具有极大的相关性,通过调整外加电场强度和时间可以实现对自封孔的调控,从而改善耐蚀性能。

The Research on Microstructure and Corrosion Resistance of Applied Electricity with Self-sealing and Micro-arc Oxidation Coatings of AZ91D Magnesium Alloys

Metal surface corrosion and wear can be improved by micro-arc oxidation. The micro-arc oxidation coatings commonly exhibited porous structure, which is considered to be main reason for failure of corrosion resistance and high temperature oxidation resistance. Arsing of that, in this paper, the corrosion resistant properties of micro-arc oxidated coatings was improved by self-sealing microstructure through an applied electric field. The relationship between the porous structure of the oxidation coatings and corrosion was investgated by microstructure anylisis. Meanwhile, regularity relations of colloid motion-potential-porous structure during sealing process was discussed and the corrosion resistance of the coatings after self-sealing was evaluated by electrochemical corrosion test. The main results showed that the porous structure of the coatings is the channel corrosive medium, and corrosion resistance can be improved by the self-sealing. In addition, corrosion resistance exhibited significant dependence on porosity, composition and morphology of sealings. It is known from this paper, the corrosion resistance can be improved by self-sealing microstructure obtained by applied electric field.