镀锌层高耐蚀三价铬黑色钝化工艺

High Corrosion Resistance Trivalent Chromium Black Passivation Process of Zinc Coating

采用正交试验优化镀锌层三价铬黑色钝化液的各个组分,在此基础上考察各种工艺条件对钝化膜的外观、耐蚀性和附着力的影响,确定了三价铬黑色钝化工艺的配方及工艺参数。三价铬黑色钝化工艺为:7.5 g/L Cr^(3+),21 g/L络合剂,22 g/L磷酸二氢钠,15 g/L过渡金属盐,0.4 mL/L有机硫化物,0.4 mL/L纳米硅溶胶,pH为2.0,θ为50℃,钝化t为45 s。该钝化工艺得到的钝化膜均匀黑亮,附着力良好,在未加封闭的情况下,耐蚀性达到中性盐雾60 h以上。

By means of orthogonal test method,components of trivalent chromium black passivation solution were optimized,on this basis,influences of various technological conditions on appearance,corrosion resistance and adhesion of the passivation film were investigated,formula and technical parameters of the trivalent chromium black passivation process were determined. The trivalent chromium black passivation process was as follows： 7. 5 g/L Cr（3＋）,21 g/L complexing agent,22 g/L sodium dihydrogen phosphate,15 g/L transition metal salts,0. 4 mL/L organic sulfide,0. 4 mL/L nano-silica sol,pH value 2. 0,temperature 50 ℃,passivation time 45 s. The passivation film obtained by this process was uniform black and bright,had good adhesion and good corrosion resistance passing more than 60 h neutral salt spray test under the unsealed conditions.