目的 通过研究硅锰钼系转化膜的新工艺，获得性能优良的膜层。方法 采用单因素实验确定工艺条件，通过电化学方法研究成膜过程，采用盐雾实验检验膜层的耐蚀性能，采用划格法测试附着力，采用测厚仪测量膜厚，使用扫描电镜观察试样的表面形貌。结果 筛选出最佳工艺条件为：磷酸二氢锰2.0 g/L，钼酸钠4 g/L，单宁酸0.4 g/L，氟化钠1.6 g/L，氟硅酸3 mL/L，pH=5，成膜时间8 min。所得转化膜均匀，呈非晶态，平均厚度为2.0 μm，与基体的附着力达到0级。结论 硅锰钼系转化膜的制备工艺中无促进剂亚硝酸钠，所得转化膜的厚度、耐腐蚀性及附着力能满足生产需要。

The work aims to obtain high performance film by studying new process of silicon manganese molybdenum conversion coating. Single factor experiment was performed to determine process conditions. Film-forming process was studied in electrochemical method. Corrosion resistance of the film was tested be performing salt spray test. Adhesion, film thickness and surface morphology of the film was measured by performing cross cut test, using thickness gauge and SEM. Optimal process conditions were selected as: manganese dihydrogen phosphate of 2.0 g/L, sodium molybdate of 4 g/L, tannin of 0.4 g/L, sodium fluoride of 1.6 g/L, fluosilicate of 3 mL/L, pH of 5 and film-forming time of 8 min. The as-prepared conversion coating was amorphous and uniform, average thickness was 2.0 microns, adhesion to the substrate reached grade 0. No sodium nitrite accelerator is used in the preparation process of silicon manganese molybdenum conversion coating. Thickness, corrosion resistance and adhesion of the as-prepared conversion film meet production needs.