Study on the Process of Electroless Ni Coating Deposited on the 6061 Aluminum Alloy

Electroless Ni-P alloy plating was taken on 6061 aluminum alloy.In accordance with the coatings hardness,the orthogonal testing method was used to screen the nickel plating solution,an optimum formula of electroless Ni-P was obtained,the optimized bath composition contained 25 g/L nickel sulphate hexahydrate,25 g/L sodium hypophosphite,20 g/L sodium acetate trihydrate,20 g/L lactic acid.The effect of sodium dodecyl sulfate,temperature and pH on the property of the coatings were discussed.The results indicate that as the concentrayion of the sodium dodecyl sulfate is 0.5 g/L,the porosity is less;The coating grows lighter and harder but the adhesion strength grows bad with the mcreasement of pH and temperature,when the under the condition of pH 4.78,the temperature 70 ℃ and plating 6 h,the hardness of the obtained coating is 476.8HV and the adhesion strength is better.