镀锌钢三价铬彩色钝化工艺优选

Optimization of Cr(Ⅲ) Colorized Passivation for Galvanized Steel

为了开发环保型的镀锌层彩色钝化液,以正交试验和极差分析的方法,研究了镀锌层表面三价铬彩色钝化液的组成,通过单因素试验法研究了成膜温度、p H值、钝化时间、空停时间及干燥方式对钝化膜外观颜色及耐蚀性能的影响,并对工艺参数进行优化。结果表明:钝化液的最佳组分为7.5 g/L硝酸铬、6.0 g/L柠檬酸、1.0 g/L硝酸钠、1.0 g/L硫酸钴、2.0 g/L氯化钠;最佳工艺参数为p H值2.5,成膜温度35℃,钝化时间90 s,空停时间20s,电吹风干燥;采用本法对镀锌层进行彩色钝化,膜表面质量及耐腐蚀性能最好。

A kind of environment friendly Cr(Ⅲ) colorized passivation solution for zinc coating was prepared,and its composition was studied by orthogonal experiments and extremum difference analysis.Moreover,the influences of the working condition(pH value,passivation temperature,passivation soaking time,stop time and drying condition) on appearance quality and corrosion resistance were researched by single- factor experiment.Results showed that the optimal components of passivation solution were 7.5 g/L chromic nitrate,6.0 g/L citric acid,1.0 g/L sodium nitrate,1.0 g/L cobaltous sulfate and 2.0 g/L sodium chloride.Additionally,the optimal process parameters were as follows:pH =2.5,passivation temperature 35℃,passivation time 90 s,stop time 15 s and drying by hair dryer.The colorized passivation layer on the zinc coating by this method had the finest appearance quality and the best corrosion resistance.