电镀锌三价铬彩色钝化膜封闭剂的制备

目的制备性能良好的封闭剂,以提高电镀锌三价铬彩色钝化膜的耐蚀性。方法以氟化钠、硅酸钠、OP为主要原料制备封闭剂。采用5%醋酸铅点滴法测定封闭处理后的电镀锌三价铬彩色钝化膜的耐蚀性能,探讨了封闭剂的配方,分析了封闭时间、烘干温度、烘干时间等工艺条件对耐蚀性的影响,并通过正交试验对封闭工艺进行了优化,确定了以氟化钠和硅酸钠为主盐的封闭剂的钝化处理工艺规范。结果试验得到的封闭剂组成为:氟化钠0.2 mol/L,硅酸钠0.05 mol/L,OP 1 m L/L。采用该封闭剂,在浸渍时间20min、烘干温度80℃的条件下,醋酸铅点滴实验最高达到近900 s。结论封闭后膜层呈彩虹色,色泽明亮,钝化膜耐蚀性提高。

Preparation of Cr III-based Iridescent Passivation Flim Sealant on Zinc Coatings

The work aims to improve corrosion resistance of Cr III-based iridescent passivation film on zinc coatings by preparing a fine sealant. Principal raw materials of sealing agent were as follows: NaF, Na2SiO3 and OP. The corrosion resis-tance of Cr III-based iridescent passivation film subject to sealing treatment was studied by 5% lead acetate drop method. For-mulation of the sealant was discussed; effects of such process conditions as sealing time, process conditions baking temperature and baking time on corrosion resistance were analyzed; the sealing process was optimized by performing an orthogonal test, so as to determine passivation process specification for sealants with NaF and Na2SiO3 as main salts. The sealant composition ob-tained was: NaF of 0.2 mol/L, Na2SiO3 of 0.05 mol/L and OP of 1 mL/L. The duration of lead acetate drop experiment might amount to 900 s provided with NaF of 0.2 mol/L, Na2SiO3 of 0.05 mol/L, immersion time of 20 min and baking temperature of 80℃. After being sealed, the film is iridescent and bright, and is provided with better corrosion resistance.