清洁型免水洗常温锰钙钡系磷化液的研究

Study on Cleaning and Free-washing Mn-Ca-Ba Phosphating Solution at Room Temperature

以磷酸二氢锰、硝酸钙、硝酸钡、钼酸钠等为原料配制锰钙钡系磷化液,对Q235钢铁试片进行常温磷化,磷化后免水洗,自然干燥3 h以上,获得了彩色锰钙钡系磷化膜。分析了磷化膜的形貌和组成,考察了磷化液pH值、磷化温度、磷化时间、磷化量等工艺条件对磷化膜性能的影响。结果表明,在磷化液pH值2.3～2.8、磷化温度5～40℃下浸渍磷化8～10 min,可生成连续、致密且颗粒细小的免水洗锰钙钡系磷化膜;磷化膜由Fe,Mn,Ca,Ba的磷酸盐及少量钼酸盐等组成,耐硫酸铜溶液腐蚀时间>85 s,膜质量0.9 g/m2左右,喷涂铁红环氧底漆后的涂层附着力达1级。

Q235 Steel specimen was phosphated at room temperature in the Mn-Ca-Ba phosphating solution consisting of manganese dihydrogen phosphate, calcium nitrate, barium nitrate and sodium molybdate. Washing-free, colorful phosphate coating was formed after natural drying for 3 hours. The effect of pH value, temperature, treatment time and the lifetime of phosphating solution on the properties of the phosphate coating was investigated. Moreover, the morphology and component of the phosphate coating were analyzed. The results show that continuous and compact phosphate coating is obtained when the specimen is phosphated for 8 - 10 min under 5 - 40 ℃ with phosphating solution, whose pH value is 2.3 - 2.8. The particles of the phosphate coating are very fine. The phosphating coating is composed of phosphate of Fe, Mn, Ca and Ba and a little of molybdate. The time of copper sulphate solution corrosion resistance is more than 85 s, and the weight of coating is around 0.9 g/ m^2. The adhesion of the coating reaches 1 grade after being sprayed with iron-red epoxy primer.