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通过正交试验研究了以磷酸盐-高锰酸盐为基础的镁合金无铬转化工艺,讨论了工艺参数对转化膜厚度及其有机涂层耐蚀性的影响,并通过扫描电镜、能谱等方法分析了转化膜的微观形貌和化学成分。研究表明,当磷酸二氢铵为10～15g/L、高锰酸钾为5～10g/L时,磷酸盐-高锰酸的最佳处理工艺为:ZnSO43g/L,NaF3g/L,pH3,温度45°C。转化液pH对膜层厚度及有机涂层的耐蚀性有显著的影响。在试验参数范围内,转化膜的厚度及后续有机涂层的耐蚀性能随pH的减小而大幅度提高。经该工艺处理后,后续有机涂层的耐蚀性能提高10倍以上。
The orthogonal experiment was carried out to study the chromium-free conversion process of magnesium alloy based on phosphate-permanganate. The effects of process parameters on the thickness of the conversion coating and the corrosion resistance of the organic coating were discussed. SEM, And other methods to analyze the microstructure and chemical composition of the conversion coating. The results showed that when the concentration of ammonium dihydrogen phosphate is 10 ~ 15g / L and potassium permanganate is 5 ~ 10g / L, the optimal treatment process of phosphate - permanganate is ZnSO43g / L, NaF3g / L, pH3, Temperature 45 ° C. The pH of the conversion solution has a significant influence on the film thickness and the corrosion resistance of the organic coating. Within the range of experimental parameters, the thickness of the conversion coating and the corrosion resistance of the subsequent organic coating are greatly enhanced with the decrease of pH. After the process, the corrosion resistance of the subsequent organic coating can be improved more than 10 times.