铝基化学镀镍浸镍前处理的研究进展

铝基表面欲获得结合力好的镀层,关键在于前处理工艺的选择。尽管浸锌法是目前研究较多、效果较好的前处理方法,但仍存在一些不足,而浸镍法可以避免这些不足,有望取代浸锌法。较详细地阐述了浸镍法的原理及研究现状,并将文献中涉及的浸镍法分为活化浸镍、碱性预镀镍和二次浸镍。活化浸镍液中一般不含还原剂,主要通过置换反应生成一层具有催化作用的镍,进而促使化学镀过程中镍紧密均匀地沉积;碱性预镀镍则是通过含有还原剂的镍盐溶液,在铝基表面预化学镀上一薄层镍,其原理与化学镀镍相同。同时,对比分析了两种浸镍法及其组合处理法之间的区别与联系。最后,指出了浸镍法未来的发展方向:其一,简化工艺,用一次浸镍法代替二次浸镍法;其二,无毒、低污染,研发出无氟浸镍液;其三,获得高性能,即优化浸镍液配方,使得镀层与基体结合强度更好。

Study on the Development of Nickel Immersion Pretreatment of Electroless Nickel Plating on Al Alloy Surface

The key line to obtain electroless nickel plating with excellent adhesion to the substrate is the pretreatment process. The zincate treatment method as a pretreatment process has been studied by many researchers, and its effect is good. However, its disadvantages cannot be ignored. The nickel immersion method can avoid these shortages, and it is expected to replace zinc immersion method. The present article introduced the research status and the principle of zincate treatment. At the same time, this paper divided the relative zincate treatment into activation-nickel immersion method, alkaline elctroless nickel pre-plating method, and double nickel immersion method. The solution of activation-nickel immersion method normally does not contain reducing agent. This method produces a thin layer of nickel catalyst by substitution reaction, prompting the deposition of electroless nickel plating closely and evenly in the later process. The solution of alkaline nickel pre-plating is a kind of nickel salt solution with certain reducing agent which pre-plates a thin layer of nickel on the surface of aluminium base. The principle of this method is the same as electroless nickel plating. This paper analyzed the difference and the relationship of the two kinds of nickel immersion methods and the combined treatment. Finally, this paper pointed out the development direction of nickel immersion pretreatment process for aluminum alloy as follows. First, in order to simplify the process, the single nickel immersion method is expected to replace the double nickel immersion method. Second, the non-poisonous, low-contaminative and fluoride-free solution of nickel immersion is expected to be developed. Third, the formulation of nickel immersion solution should be optimized to make the bonding strength better.