AZ 31镁合金锡化膜上化学镀Ni-P层性能的研究

A Research on the Performance of Stannate Conversion Film plus Electroless Ni-P Coating on AZ 31 Magnesium Alloy

将化学转化与化学镀镍相结合,对AZ 31镁合金先进行锡酸盐转化处理,再在锡化膜上化学镀Ni-P层。对锡化膜及化学镀Ni-P层的成分、结构和耐蚀性能进行了研究。结果表明:AZ 31镁合金基体表面所形成的锡化膜是由细小、均一的近似球状的微粒密积而成,微粒间存在的间隙可为后续化学镀Ni-P层提供良好的吸附条件,对改善镀层与基体间的结合力有一定的作用。在质量分数为3.5%的NaCl溶液中的阳极极化曲线表明:锡化膜上化学镀Ni-P层的耐点蚀性能好于化学镀Ni-P层的。环形阳极极化曲线及盐雾和浸泡实验显示:锡化膜上化学镀Ni-P层具有更好的耐中性NaCl点蚀性能。

In order to improve the corrosion resistance of AZ 31 magnesium alloy,electroless Ni-P plating is combined with chemical conversion treatment,that is,the alloy is first treated with stannate conversion,and then electroless Ni-P plating is carried out on the conversion film.The compositions,structure and corrosion resistance of the conversion film and the electroless Ni-P coating were studied.The results show that stannate conversion film on the surface of AZ 31 magnesium alloy film is formed by small uniform spherical particles,between which the gaps can provide good adsorption conditions for subsequent electroless Ni-P plating,that can improve the bonding strength between coating and substrate to some extent.The anodic polarization curves in NaCl solution with a mass fraction of 3.5 % show that the pitting corrosion resistance of the electroless Ni-P coating on stannate conversion film is better than that of conventional electroless Ni-P coating,and circular anodic polarizalion curves,salt spray and immersion test show that the stannate conversion film plus electroless Ni-P coating has a better pitting corrosion resistance of neutral NaCl solution.