硫酸铈对三价铬钝化膜耐腐蚀性的影响研究

目的研究硫酸铈对三价铬钝化膜耐蚀性能的影响。方法通过在三价铬镀铬盐溶液中分别添加0.3、0.5、0.8、1.0、1.5 g/L的硫酸铈,然后通过极化曲线测试,对比不同硫酸铈添加量的钝化膜的腐蚀电流密度,确定硫酸铈在三价铬镀铬盐溶液中的最佳添加量,然后分别制备未添加硫酸铈和添加最佳添加量硫酸铈的三价铬钝化膜,通过电化学工作站CHI660E测量Tafel极化曲线和电化学阻抗谱。分析钝化膜的电化学性能,研究不同钝化膜的耐腐蚀性。观察试样表面的微观形貌,对比添加硫酸铈和未添加硫酸铈的钝化膜的微观形貌。结果通过极化曲线测试发现,当硫酸铈的添加量为1.0 g/L时,钝化膜的腐蚀电流密度小于其余添加量的钝化膜,添加硫酸铈和未添加硫酸铈的钝化膜的耐蚀性能不同,添加硫酸铈后的钝化膜性能得到改善,且钝化膜膜层的微观形貌发生改变。结论添加硫酸铈后,三价铬钝化膜的耐腐蚀性能增强。当硫酸铈的添加量为1.0 g/L时,腐蚀电流密度最小,为3.835×10~(-6) A/cm~2,耐腐蚀性能优于其余钝化膜。

Effects of Cerous Sulfate on the Corrosion Resistance of Trivalent Chromium Passivation Film

The work aims to study the effects of cerous sulfate on corrosion resistance of trivalent chromium passivation film. 0.3 g/L, 0.5 g/L, 0.8 g/L, 1.0 g/L and 1.5 g/L of cerium sulfate was added in trivalent chromium plating salt solution respectively. Then the corrosion current density of passivation film added with different addition volumes of cerous sulfate was compared through polarization curve test so as to determine optimal addition volume of cerous sulfate in the trivalent chromium plating salt solution. Later, trivalent chromium passivation films without cerous sulfate and with optimal addition volume of cerous sulfate were prepared respectively. Tafel polarization curve and electrochemical impedance spectroscopy (EIS) were measured by electrochemical workstation CHI660E. Electrochemical properties of the passive films were analyzed and the corrosion resistance of different passivation films was studied as well. The morphology of the passivation films with and without cerium sulfate cerium sulfate was compared. When the addition volume of cerous sulfate was 1.0 g/L, corrosion current density of the passivation film was less than that of passivation films with other volumes of cerous sulfate. Corrosion resistance of passivation film with cerous sulfate differed from those without cerous sulfate, and the former was provided with better performance and different morphology. Therefore, corrosion resistance of the trivalent chromium passivation film is improved when added with cerous sulfate. The corrosion current density is the minimum 3.835×10-6 A/cm2 and the corrosion performance is superior to that of other films when 1.0 g/L of cerous sulfate is added.