LY12铝合金铈化学转化膜的结构及耐蚀性研究

应用电化学方法及腐蚀试验研究了LY12铝合金表面常温稀土化学转化膜。结果表明，铝合金的稀土化学转化膜具有成膜温度低、速度较快、膜的耐蚀性能好等优点。电位－时间曲线表面，成膜动力学包括铝合金的溶解及随后的成膜两个过程。SEM表明，铝合金稀土化学转化膜的形态为片状，EDAX能谱表明转化膜主要由Ce,O,Al及少量的促进剂离子组成。腐蚀试验表明，未经处理的铝合金在3．5%NaCl溶液中经过21天浸泡后，表面出现了严重的点蚀，而经稀土处理的铝合金经过相同时间的浸泡后，表面只发生了轻微的均匀腐蚀，而未发生点蚀，浸泡后稀土处理的铝合金的失重较空白试样的下降了近1倍，铝合金的耐蚀性能大大提高。

Structure and Corrosion Resistance of Cerium Conversion Coatings for LY12 Aluminum Alloy

The cerium conversion coatings on LY12 aluminum alloy surface under normal temperature was studied by electrochemical methods and corrosion experiments. Results showed that the conversion coatings process had such advantages as low temperature and quick coatings formation, and also higher corrosion resistance. The potential|time curves showed that the coatings formation involved two processes, i.e. the dissolution of the metal and the formation of coatings. SEM showed that the coatings were in the form of flake, which consisted of Ce, O, Al and few ion of the additive indicated by the EDAX tests. Serious corrosion occurred for the blank aluminum alloy immersed for 21 d in 3.5% NaCl solution, especially pitting corrosion. While pitting wasn't observed on the surface of the sample treated by the cerium , but only slightly general corrosion. The immersion tests showed that the weight loss of samples treated by cerium salt was almost half of the blank sample. The corrosion resistance of aluminum alloy was greatly increased by the coatings.