磷酸盐转化膜耐蚀性的影响
(1. 山东科技大学 材料科学与工程学院，青岛 266510；
2. 重庆理工大学 材料科学与工程学院，重庆 400050)
摘 要: 采用化学沉积方法在AZ31镁合金表面制备锌钙系磷酸盐转化膜。利用扫描电子显微镜(SEM)和电化学方法研究镀液温度对镁合金AZ31表面磷酸盐转化膜表面形貌及其耐蚀性能的影响。利用电子能谱仪(EDS)、光电子能谱(XPS)和X射线衍射仪(XRD)分析膜层化学成分、相结构。研究表明：当温度为50 ℃时，转化膜层晶粒均匀、完整，耐蚀性较好；膜层化学成分主要由O、P、Zn和Mg元素以及微量Ca组成，主要相组成为Zn3(PO4)2·4H2O；锌钙磷酸盐转化膜比磷酸锌转化膜具有更小的晶粒和更好的耐蚀性。
关键字: 镁合金；磷酸盐转化膜；镀液温度；耐蚀性
（1. School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266510, China;
2. School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400050, China）
Abstract:Zinc calcium phosphate conversion films were prepared via chemical deposition on AZ31 magnesium alloy. The influence of the temperature of phosphate baths on the surface morphologies of phosphate conversion films on AZ31 magnesium alloy and their corrosion resistance were investigated by scanning electron microscopy (SEM) and potentiodynamic electrochemical tests, respectively. And the phase constitutes and chemical compositions of the coatings were analyzed by electron energy X-ray spectrum (EDS), X-ray photoelectron spectrum (XPS) and X-ray diffraometry (XRD). The results show that the chemical conversion coatings, which are mainly composed of Zn3(PO4)2·4H2O, contain O, P, Zn and Mg as well as a trace of Ca. The phosphate conversion films are characterized to be homogenous fine grains and completely covered on the surface; and the corrosion resistance of the coatings obtained at the temperature of 50 ℃ is optimum. The calcium-containing phosphate conversion films with finer grains on magnesium alloy can more significantly enhance the corrosion resistance than zinc phosphate conversion films.
Key words: magnesium alloy; phosphate conversion film; bath temperature; corrosion resistance
