镁合金表面钼酸盐转化膜的制备及其耐蚀性能  

Preparation and Corrosion Resistance of Molybdate Conversion Coating on Magnesium Alloy

作　　者：吴海江[1] 许剑光[1] 郭世柏[1] 李会强[1] 蔡春波[1] 

机构地区：[1]湖南科技大学机电工程学院,湖南湘潭411201

出　　处：《材料保护》2010年第10期14-16,52,共4页Materials Protection

基　　金：湖南省自然科学基金(10JJ6084)资助

摘　　要：钼酸盐毒性低,有良好的缓蚀性能,可代替有毒的铬酸盐用于镁合金表面的耐蚀处理。采用正交试验优选了钼酸盐转化工艺中的Na2MoO4.2H2O浓度、NaH2PO4.2H2O浓度、pH值、成膜温度和时间,考察了压铸AZ91D镁合金在优化工艺条件下所得钼酸盐转化膜的耐蚀性能,利用扫描电子显微镜(SEM)、能谱仪(EDS)和中性盐雾腐蚀试验(NSS)等手段研究了转化膜的组成和形貌。结果显示:钼酸盐转化膜主要由Mg,A l,Mo,P和O等元素构成,膜层较为平整、均匀、致密,并存在一些不规则的微裂纹;钼酸盐转化膜有效地提高了AZ91D镁合金的耐蚀能力。Orthogonal experiments were carried out to determine the optimized bath composition and parameters(concentration of NajMoO,,? 2H2O and NaH2PO4 ? 2H2O,pH value,film-formation temperature,filmformation time) for preparing molybdate conversion coating on AZ91D Mg alloy.The composition and morphology of resultant coating were analyzed by means of scanning electron microscopy and energy dispersive spectrometry.The corrosion resistance of the conversion coating was evaluated by neutral salt spray tests.Results indicate that as-prepared molybdate conversion coating consists of Mg,Al,Mo,P and O,and is smooth,uniform and compact,showing a small amount of micro-cracks.The coating could effectively improve the corrosion resistance of the Mg alloy.

关 键 词：转化膜 钼酸盐 镁合金 耐蚀性 正交试验 组成 形貌 

分 类 号：TG174.45[金属学及工艺—金属表面处理]