镀锌层硅酸盐无铬黑色钝化工艺

Process for Chromium-Free Black Passivation of Zinc Coating in Silicate-Based Passivation Fluid

硅酸盐环境友好、成本低、性能稳定,用于镀锌件无铬黑色钝化,目前尚无报道。以硅酸为主盐对镀锌件进行了无铬黑色钝化,研究了钝化液各组分、钝化工艺条件对钝化膜外观及耐蚀性能的影响,获得了最优的钝化工艺。结果显示:镀锌件钝化膜外观乌黑、光亮,色泽均匀;耐5%NaCl盐雾腐蚀达160 h,优于现有的三价铬盐钝化工艺。

Silicate was used as the major salt to formulate Cr-free black passivation fluid for Zn coating.The effects of composition of passivation fluid and passivation condition on the appearance and corrosion resistance of the passivation film were investigated,and the optimal passivation condition was established.It was found that the passivation film on the Zn coating was black and bright,and had even luster.Besides,the passivation film possessed better corrosion resistance than trivalent chromate passivation film,enduring 5% NaCl salt-spray of 160 h.