摘要
采用磷酸盐-高锰酸盐溶液在AZ31镁合金表面制备了化学转化膜。采用田口正交矩阵法,以转化膜在3.5%NaCl溶液中的极化电阻作为指标以及根据信噪比的计算,分析了高锰酸钾质量浓度、溶液pH、转化时间和转化温度对转化膜耐蚀性的影响,获得最优条件为:Na_2HPO_4 100 g/L,KMnO_4 20 g/L,温度80°C,pH 3,时间10 min。将优化工艺制备的化学转化膜作为介质阻挡层,在硅酸钠-氢氧化钾电解液体系中,利用等离子体电解氧化技术(PEO)在300 V下处理30 min,得到陶瓷涂层。考察了该化学转化膜对PEO放电特性,以及陶瓷涂层形貌、膜厚、成分和耐腐蚀性能的影响。与无预制转化膜的陶瓷涂层相比,有预制化学转化膜的陶瓷涂层的组分差别不大,但极化电阻提高了2个数量级,膜厚增加近一倍。
A chemical conversion film was prepared on AZ31 magnesium alloy using a permanganate-phosphate solution. The effects of mass concentration of potassium permanganate, pH of solution as well as conversion temperature and time on corrosion resistance of the conversion film were analyzed by Taguchi orthogonal array method using the polarization resistance of the conversion film in 3.5% NaCl solution and the calculated signal-to-noise ratio as evaluation indexes. The optimal conditions were obtained as follows： Na2HPO4 100 g/L, KMnO4 20 g/L, temperature 80 ℃, pH 3, and time 10 min. The film prepared under the optimal conditions was used as a dielectric barrier layer, on which a ceramic coating was formed from a sodium silicate-potassium hydroxide electrolyte by plasma electrolytic oxidation （PEO） at 300 V for 30 min. The effect of chemical conversion film on the PEO discharge characteristics as well as the morphology, film thickness, composition and corrosion resistance of the ceramic coating was studied. The ceramic coating formed with pre-prepared chemical conversion film has similar composition as that formed without pre-prepared chemical conversion film, but its polarization resistance is increased by two orders of magnitude and its thickness is nearly doubled.
出处
《电镀与涂饰》
CAS
CSCD
北大核心
2016年第15期793-798,共6页
Electroplating & Finishing
基金
广东省自然科学基金(2015A030313766)
国家级大学生创新创业训练项目(201411656002)
广东省大学生创新创业训练项目(1165613004
1165613011
201411656025)
茂名市科技计划资助项目(201312
20140310)
茂名市石油化工腐蚀与安全工程技术研究开发中心开放基金
关键词
镁合金
化学转化
介质阻挡层
等离子体电解氧化
陶瓷涂层
田口正交矩阵法
耐蚀性
magnesium alloy
chemical conversion
dielectric barrier layer
plasma electrolytic oxidation
ceramic coating
Taguchi orthogonal array method
corrosion resistance
