Ni-Cd合金镀层中Cd含量对镀层耐蚀性能的影响

Effect of Cd content in Ni-Cd alloy plating on corrosion resistance of the plating

采用电刷镀的方法在钢铁构件表面镀覆一层Ni-Cd合金镀层,从而实现牺牲阳极和机械保护法的双重保护机制;采用控制变量法研究镀液中不同浓度的Cd^(2+)对于镀层耐蚀性能的影响。通过极化曲线、电化学阻抗谱、全浸腐蚀实验以及盐溶液周浸实验分别测定不同Cd^(2+)浓度下镀层的腐蚀电位、极化电阻以及耐蚀性能。结果表明:当Cd^(2+)摩尔分数从0.5%~5%变化时可以实现Cd质量分数为15%~90%的Ni-Cd合金的共沉积;其中,当Cd^(2+)摩尔分数为4%时,即镀层中Cd质量分数为69.40%时,合金刷镀层的耐蚀性最好。

A Ni-Cd alloy plating is applied to the surface of steel component by brush plating,which can realize the double protection of sacrificial anode by cathodic protection and mechanical protection.The effect of concentration of Cd^(2+) in plating solution on the corrosion resistance of the plating was studied by using the control variable method.The corrosion potential,polarization resistance and corrosion resistance of the coating with different concentrations of Cd^(2+) were measured by polarization curve,AC impedance spectroscopy,full immersion corrosion test and salt solution immersion test.The results show that the codeposition of Ni-Cd alloy with Cd of mass fraction of 15%-90% can be realized when the mole fraction of Cd^(2+) changes from 0.5%-5%,which belongs to abnormal co-deposition.When the molar fraction of Cd^(2+) is 4 %,that is,the mass fraction of Cd^(2+) in the coating is 69.40 %,and the corrosion resistance of the alloy brush coating is the best.