钼和硼对热镀锌钢板表面矾酸盐成膜的影响

Effect of molybdate and borate on vanadate conversion film in hot galvanizing

使用过硼酸钠和钼酸盐作为促进剂制备转化液,通过扫描电镜观察钒酸盐转化膜在形核、生长过程中的形貌变化,采用化学法对转化膜质量进行了检测分析,通过中性盐雾试验对膜层的耐蚀性进行测试,采用电化学工作站对膜层在5%Na Cl溶液中的腐蚀行为进行了研究。结果表明,过硼酸钠提高了转化膜中钒化合物的质量分数,有助于得到较厚且致密的转化膜;钼酸钠可以促进转化膜形核,加快膜层的初期生长速度;在腐蚀环境中,混合价态的钒化合物通过抑制阴极区域氧的还原反应,从而起到对镀锌层的保护作用。

Sodium perborate and molybdate were used as accelerant to prepare the conversion fluid. The process of nucleation and growth of vanadate conversion coating were observed by scanning electron microscopy. The film weight was analyzed by chemical method and the corrosion resistance of the coating was tested by neutral salt spray test,the corrosion behavior of the coating in 5%Na Cl was analyzed by electrochemical workstation. The results indicate that sodium perborate improved the mass percent of vanadium compound in the transformation film,and it was helpful to create thick and dense transformation film;sodium molybdate can promote the nucleation of conversion film and accelerate the initial growth rate of the film. In the corrosion environment,mixed valence state compound of vanadium can protect the zinc layer by inhibition the reduction of oxygen in the cathode area.