Preparing of Ni-Cu-P Coating

Ni-Cu-P coating by chemical plating has excellent corrosion resistance,wear resistance, thermal stability and electrical conductivity. In this paper, Ni-Cu-P was prepared by chemical deposition methods, the optimum process of chemical plating Ni-Cu-P. By using scanning electron microscopy(SEM), spectrum analyzer, Autolab workstation on the corrosion resistance of the coating. The results showed that: (1)after the specimen surface chemical plating nickelcopper phosphorus treatment, in the same corrosion potential, the corrosion current density was lower than that of Ni-P coating and substrate materials; (2)had a significant effect on corrosion resistance of quantity of citric acid sodium on nickel copper phosphorus alloy plating, coating corrosion resistance with increasing citric acid sodium content first increased and then decreased, and inaddition level of sodium citrate is 40g/L, the corrosion current density reaches a minimum, 14.51×10–6A/cm2; (3)under the same conditions, the Ni-Cu-P alloy coating pH impact is the biggest,the maximum impedance 1268.05Ω; (4)in the 3.5%NaCl solution, with the change of copper content, the main trend of the corrosion current is decreased first and then increased, and the content of copper in Energy spectrum analysis within 5.18Wt% corrosion current density of a minimum of 14.51×10–6A/cm2, the corrosion resistance. With the increase of Cu content in the coatings, the P content first increased and then decreased in the coating, the content of Ni decreased first and then increased; (5)the best technology:NiSO46H2O, CuSO4 25g/L, 5H2O 0.15g/L, C6H5Na3O7•2H2O 40g/L, NaH2PO2H2O 25g/L, CH3COONa 15g/L, KIO3 0.03g/L, C12H25NaO4SO3 0.01g/L, pH4.75 ± 0.01,temperature 80 ± 1 °C, deposition time of 2h.