Technology of Electroless Ni-P Alloy Plating on Aluminum Alloy

The effect of temperature,pH value,content of sodium citrate and sodium hypophosphite on the corrosion resistance of Ni-P electroless coating on aluminum alloy was investigated by using single factor and orthogonal methods.A suitable electroless Ni-P alloy plating condition with higher deposition rate and corrosion resistance was obtained.The results show that the optimal processing parameters are NiSO4 · 6H2O 25g/L,NaH2PO2 · H2O 24g/L,C6H5Na3O7 · 2H2O 45g/L,CH4N2S 2mg/L,CH3COONa · 3H2O 0.1 g/L,OP-10 0.5mL/L,pH value of 8.0,processing time of 50 min,temperature of 70℃.Under this condition,the plating rate of Ni-P coating reaches to 20 g/(m2·h),and the coating has a uniform surface,higher corrosion resistance and better adhesion with the thickness of 19μm and hardness of 528.25 HV.