摘要
采用X射线光电子能谱(XPS)、原子力显微镜(AFM)、电化学方法等对AZ31镁合金铈转化膜的组成、形貌结构及耐蚀性能进行了表征,并结合成膜动力学研究探讨了膜的形成机制。结果表明,镁合金铈转化膜的主要成分为铈的氧化物/氢氧化物,铈在膜中以三价和四价两种价态存在。膜可以分为两层,内、外层膜由不同的微结构组成,这种微结构的差异使内、外层膜之间结合力较弱,成为限制膜耐蚀性能提高的根本原因之一。成膜过程中,成膜溶液pH值升高,使Ce3+发生水解反应沉积析出铈的氢氧化物/氧化物。铈转化膜的生长动力学遵循抛物线规律。
Cerium conversion coating formed on AZ31 magnesium alloy was characterized and the formation mechanism was discussed. X-ray photoelectron spectroscopy （XPS） analysis showed that cerium conversion coating consisted of cerium hydroxides/oxides, in which both tetravalent cerium Ce （Ⅳ） and trivalent cerium Ce （ Ⅲ ） species co-existed. Cerium conversion coating was in a two-layer structure. Atomic force microscopy （AFM） characterization revealed that the in-side layer had different morphology from the outside one, which was responsible for the inherent adhesive weakness of the coating. Corrosion potential measurements indicated that the poor adhesion limited the improvement of the coating corroion resistance. During the treating process, the increasing pH of the solution caused the precipitation of cerium hydroxides/oxides. The formation kinetics of the coating followed a parabola curve.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2007年第6期736-740,共5页
Journal of the Chinese Society of Rare Earths
基金
国家自然科学基金(20603049)
重庆市自然科学基金(CSTC
2007BB4154)
重庆市高等学校优秀中青年骨干教师资助项目
关键词
镁合金
铈转化膜
组成
形貌
成膜动力学
稀土
magnesium alloy
cerium conversion coating
composition
morphology
formation kinetics
rare earths
