镁合金阳极氧化膜的结构、成分及其耐蚀性

采用电压-时间曲线、膜厚-时间曲线、X射线衍射法、扫描电镜、能量色散谱仪、X射线光电子能谱法、全浸腐蚀实验和极化曲线等方法分别研究了AZ91D铸镁合金阳极氧化成膜动力学过程、阳极氧化膜的表面形貌、结构、元素组成、元素价态以及相成分和膜层的耐蚀性.结果表明,在阳极氧化的4个阶段中,由于各个阶段所生成膜的厚度、结构和成分等均不同,因此膜的耐蚀性相差很大;镁合金阳极氧化时耐蚀性最好的膜层是在阳极氧化过程中的第阶段和第阶段的交界处所生成的膜层;镁合金阳极氧化膜中含有Mg,O,Si,B和少量的Al,Na元素,膜层主要由MgO,MgSiO₃和Mg3B2O6组成.

Structure, Composition and Corrosion Resistance of Mg Alloy Anodized Film

The kinetics of film-forming course, the surface morphology, structure, composition and valence of element, phase constituent and the corrosion resistance of anodic films were studied by the ways of voltage-time curve, thickness-time curve, SEM, EDS, XPS, XRD, total immersion test and polarization curve respectively. The results show that there are relativity among the structure, composition and corrosion resistance of anodic films on AZ91D Mg alloy; the film-forming course can be divided into four stages, and the corrosion resistance of the anodic films in different stages have great difference because of its variation of thickness, structure and composition; the films that have the best corrosion resistance is the films formed on the boundary of stages Ⅲ and Ⅳ during the anodic course. The anodic oxidation film contains Mg, O, Si, B and a small amount of Al and Na. The dense layer is composed mainly of MgO, while the porous layer is composed of MgO, MgSiO3 and Mg3B2O6.