铝锂合金表面化学镀镍工艺及膜层耐腐蚀性能研究

为解决铝锂合金强烈电腐蚀倾向和对断裂及应变速率的敏感性,提出了在其表面进行化学镀镍处理的工艺方法。通过正交试验研究了基础化学镀镍液的主要成分对镀层性能的影响,利用扫描电子显微镜、INCA型能谱仪以及显微硬度计等分析了化学镀镍层的表面形貌、组成成分、镀层硬度等特性。研究结果表明,铝锂合金表面进行化学镀镍的可行性工艺为:15 g/L硫酸镍、25 g/L次磷酸钠、30 g/L醋酸钠、20 g/L乳酸、5 g/L硼酸、0.5~1.0 mL/L稳定剂,1.0~2.0 mL/L光亮剂,θ为85℃,施镀时间t为60 min。该工艺能在铝锂合金表面获得结合力良好、耐蚀性较好的化学镀镍层,镀镍层表面晶粒均匀细致,与基体结合力达1级,可耐中性盐雾试验时间48 h以上。

Study on the Electroless Nickel Plating on Aluminium Lithium Alloy Surface and its Corrosion Resistance

In order to solve the strong electrical corrosion tendency of Al Li alloy and its sensitivity to fracture and strain rate,process of electroless nickel plating on its surface was proposed.The effect of solution content on the coating properties was investigated by orthogonal test.The surface morphology,chemical composition and hardness properties were studied by scanning electron microscopy (SEM),INCA spectroscopy (EDS),and microhardness analysis.The best process conditions were as follows:nickel sulfate 15 g/L,sodium hypophosphite 25 g/L,sodium acetate 30 g/L,boric acid 20 g/L,lactic acid 5 g/L,brightener 1.0 ～ 2.0 mL/L,stabilizer 0.5 ～ 1.0 mL/L,plating temperature 85 ℃ and the plating time 60 min.Electroless nickel coatings with good adhesion and corrosion resistance could be obtained on Al Li alloy surface by using this process.Grain on the nickel coating surface was uniform and compact.The substrate binding force was 1 grade and resistance to neutral salt spray test time was above 48 h.