碱性镀锌层三价铬黑色钝化工艺的探讨  

Process for Trivalent Chromium Black Passivation of Galvanizing Coating Made from Alkaline Bath and Evaluation of Corrosion Resistance and Electrochemical Behavior of the Coating

作　　者：王超 张金生[2] 周长虹 吕明威 马静 

机构地区：[1]武汉奥邦表面技术有限公司,湖北武汉430023 [2]武汉纺织大学化学与化工学院,湖北武汉430073

出　　处：《材料保护》2013年第4期35-37,8,共3页Materials Protection

摘　　要：为了寻求环保、工艺技术稳定、性能优良、能投入生产的碱性镀锌层三价铬黑色钝化工艺,通过平行试验优选了碱性镀锌层三价铬黑色钝化基础液的组分,通过中性盐雾腐蚀及电化学方法测试了钝化膜的耐蚀性,确定了最佳钝化液组成及钝化工艺参数。结果表明:黑色钝化液最佳组分为0.1 mol/L Cr3+[三氯化铬∶硝酸铬=(3～5)∶1,摩尔比],有机酸配体/Cr(摩尔比)=1.6,5.0 g/L硫酸钴,3.0 g/L硫酸镍,0.5 g/L硫酸铜,10 g/L磷酸二氢钾,5.0 g/L醋酸;最佳钝化参数为温度30℃,pH值2.0,时间45 s;以此钝化工艺对碱性镀锌层进行常温黑色钝化,然后经WS-1封闭剂封闭处理,可得到黑色光亮的钝化膜,其中性盐雾腐蚀出白锈时间超过96 h。For the purpose of establishing environmentally acceptable and stable process for trivalent Cr black passivation of galvanizing coating obtained in an alkaline bath,the composition of the solution for trivalent Cr black passivation was optimized based on parallel tests.The corrosion resistance and electrochemical behavior of resultant black Cr passivation coating were evaluated by neutral salt-spray test and electrochemical test;and the optimal composition of the passivation fluid as well as the optimal passivation parameters was established.It was found that the optimal composition of the black passivation fluid was determined as 0.1 mol/L Cr3+ [CrCl3:Cr(NO3)3 =(3～5):1,molar ratio],organic acid complexing agent/Cr = 1.6(molar ratio),5.0 g/L CoSO4,3.0 g/L NiSO4,0.5 g/L CuSO4,10 g/L KH2PO4 and 5.0 g/L CH3COOH;and the optimal passivation parameters were suggested as temperature of 30 ℃,pH value of 2.0,and time of 45 s.Black and bright passivation coating could be obtained atop the title galvanizing coating after it was passivated with the trivalent Cr black passivation fluid at room temperature and sealed with WS-1 sealing agent.Resultant passivation coating was able to endure against neutral salt-spray for up to 96 h and above.

关 键 词：黑色钝化 三价铬 碱性镀锌层 封闭 耐盐雾腐蚀 电化学性能 

分 类 号：TG174.44[金属学及工艺—金属表面处理]