Technology for Electroless Plating of Cu-Ni-P Alloy on Diamond

Electroless Cu-Ni-P coating was prepared on the surface of diamond. The effects of bath composition, pH value, and plating time on the deposition rate were investigated, while the oxidation resistance of the diamond coated with the Cu-Ni-P electroless coating was analyzed using X-ray diffraction. As the results, it was feasible to prepare Cu-Ni-P alloy coating of good wear resistance, corrosion resistance, and conductivity on diamond using the optimal bath formula and plating conditions. The optimized plating bath was composed of 65~95 mg/L CuSO_4, 15~40 g/L NiSO_4, 15~30 g/L NaH_2PO_2, 5~20 g/L sodium citrate, 15~30 g/L NH_4Cl, and 12~35 mg/L KNO_3. The optimized bath pH value was suggested to be 4.5~7.6, while the temperature and plating time were suggested to be 75~95 ℃ and 15~35 min, respectively. The resulting Cu-Ni-P coating had good wear resistance and that after proper heat-treatment was able to further increase the oxidation resistance of the diamond.