Corrosion Resistance of Ternary Ni-Cu-P Coatings Prepared by Electroless Method on Carbon Steel

Ni-Cu-P coatings were prepared by electroless deposition method on carbon steel. The pH value and concentrations of cupric sulfate were studied to character the deposition rate, corrosion resistance of Ni-Cu-P coatings in 3.5% NaCl solution. From the results, it was shown that the deposition rate of Ni-Cu-P coatings increased with the increasing of pH value. The deposition rate speeds up until the deposition rate keeps stable when the pH value is about 8.0-9.0. When pH value was 7.5, the coatings showed good corrosion resistance. In the same conditions of solution compositions and technological conditions, the concentration of cupric sulfate must be lower than 2g/L if the copper and nickel altogether co-deposited. The minimal corrosion current and excellent surface state for the coatings can be obtained when the concentration of cupric sulfate was about 0.8 g/L.