Electroless Nickel Plating Technology and Influencing Factors of Performance of 2090 Aluminum Lithium Alloy

Electroless nickel plating was carried out on the surface of 2197 Al-Li alloy. The composition and surface morphology of the plating were analyzed by energy dispersive spectrometer (EDS) and scanning electron microscopy (SEM). The plating rate and corrosion resistance of the nickel plating were respectively evaluated by deposition rate and chromogenic time. The optimum additions of three complexing agents (malic acid, glycine, trisodium citrate), rare earth compounds[La (NO₃)₃, Ce (SO₄)₂] and heavy metal compound CuSO₄ were studied. The results show that a uniform fine nickel plating with cellular structure could be obtained by electroless nickel plating on the surface of 2197 Al-Li alloy. The optimum mixed formulation of complexing agent in electroless nickel plating bath was 3 g/L malic acid, 3 g/L glycine and 30 g/L trisodium citrate. The nickel plating had good corrosion resistance and fast plating rate under the optimum mixed formulation. Adding a small amount of Ce (SO₄)₂, La (NO₃)₃ and CuSO₄ in the electroless nickel plating bath could improve the plating rate, but reduce the corrosion resistance of the nickel plating. So the addition of Ce (SO₄)₂ and La (NO₃)₃ should not exceed 0.5 mg/L, and the addition of CuSO₄ should not exceed 2 g/L.