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应用电化学方法和表面分析技术研究了LY12Al合金铬 磷化转化膜的成膜工艺、膜的组成、形貌及耐蚀性.-t曲线表明，Al合金铬磷化处理 的动力学过程为Al合金的溶解和随后的成膜.极化曲线测试表明，未经封闭的Al合金的耐蚀 性能很差，而经重铬酸钾封闭后，耐蚀性大为提高.SEM、EDAX分析表明，Al合金的铬磷化膜 具有网块状结构，铬磷化膜主要由O、P、Al、Cr组成.转 化膜裂纹处Al的含量很高，P、Cr和O的含量较低，而经重铬酸钾封闭后，膜的形态没有变化 ，裂纹处Al的含量明显降低，而O和Cr的含量大为提高.

The chromate-phosphate conversion coatings on LY12 a luminum alloy surface were studied by electrochemical methods and scanning elect ronic microscopy (SEM),i.e.the treating process,the composition and the morpholo gy of coatings and its corrosion resistance in 3.5%NaCl solution. -t curve showed that the procedure of coating formation consisted of two st ages,i.e.dissolution of the alloy once immersed into the treating solution,and s ubsequently the coatings formation.The potentialdynamic polarization curves indi cated that the treated alloy without sealing had a lower corrosion resistance in 3.5%NaCl solution,but the samples sealed by K2Cr2O7 had a good corrosion resista nce in 3.5%NaCl solution.SEM experiments showed that the conversion coatings had a large of lumps with lots of crackles,EDAX analyzsis results indicated that th e coatings consisted of oxygen,phosphor,aluminum and chromium.The crackles contained large amount of aluminu m,and lower contents of oxygen and chromium.The morphology of the coatings had n ot changed,but the content of aluminum decreased greatly and the contents of oxy gen and chromium increased after K2Cr2O7 sealed.