Ni-Cd 合金镀层中Cd 含量对镀层耐蚀性能的影响

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 Cd²⁺ 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 Cd²⁺ were measured by polarization curve, AC impedance spectroscopy, full immersion corrosion test and salt solution immersion test. The results show that the co-deposition of Ni-Cd alloy with Cd of mass fraction of 15%-90% can be realized when the mole fraction of Cd²⁺ changes from 0.5%-5%, which belongs to abnormal co-deposition. When the molar fraction of Cd²⁺ is 4 %, that is, the mass fraction of Cd²⁺ in the coating is 69.40 %, and the corrosion resistance of the alloy brush coating is the best.