无铵助镀剂中铁盐对热浸镀锌镀层性能的影响

Effects of Iron Salt on Coating of Ammonium-free Plating Auxiliary

为探究热浸镀锌无铵助镀剂中铁盐对镀层的影响，选取无铁盐的无铵助镀剂及含铁盐的无铵助镀剂。采用SEM和EDS对比分析不同助镀剂所获得的镀层的组织结构和成分。结果表明：无铵助镀剂中的二价铁盐浓度为10～30以有助于提高镀层表面质量；不含二价铁盐的无铵助镀剂镀层的合金相层由Г、δ、ζ和η相组成，并且界限较明显。含二价铁盐的无铵助镀剂镀层的整个合金相层排列整齐致密，Г相几乎不存在，其中δ相和ζ相的界限不明显，并且塑性相δ相在合金相所占的比例较大，经成分分析，由无铵助镀剂带入的部分铁离子被还原成铁原子后，有促进镀层中δ相的形成，抑制￡相生长的作用。

To probe into the influences of ferric iron on the plating coating, two kinds of flux, which were the ammonium-free plating auxiliary without iron salt and the ammonium-free plating auxiliary with iron salt, were prepared. SEM and EDS were used to compare the metallographic structure of the two fluxes. Through plentiful experiment, the ferrous salts concentration within 10 g/L-30 g/L help to improve the quality of coating. The coating of the ammonium-free plating auxiliary without iron salt is composed off phase, δ phase, ζ phase and η phase, and the bounds of the four phases are clear; The phase structure of the coating of the ammonium-flee plating auxiliary with iron salt is more densification, the F phase almost does not exist, the bound between δ phase and phase is breezing, and the ductile δ phase occurs in a great proportion in the Zn-Fe alloy phase. Through the EDS component analysis, Part of ferric ion, which is reduced into iron atoms, can accelerate the growth of δ phase and restrain the growth of ζ phase.