不同表面状态热镀锌板耐腐蚀性能研究

Study on corrosion resistance of hot-dip galvanized sheet with different surface states

本研究通过中性盐雾试验,系统探究了锌层形貌及后处理方式对镀锌板耐腐蚀性能的影响。结果表明,锌层形貌及后处理方式均对镀锌板耐蚀性有较大影响。主要是因锌花形貌会使镀锌板表面粗糙度增大,导致镀锌板在盐雾箱内与腐蚀介质接触的实际有效面积大,同时锌层表面偏析的第二相粒子形成阴极活化点,促进电化学反应,加快腐蚀速率;涂油属于物理隔离防腐措施,在盐雾箱内大量的水雾会将镀锌板表面所涂防锈油冲洗掉,并不能起到保护锌层的作用,该方法处理的镀锌板防腐性能最差。钝化处理会在锌层表面形成一层连续的、不溶于水的、致密的保护层,抑制电化学腐蚀中的阳极反应,采用钝化处理的钝化板耐盐雾腐蚀性能最好。钝化后再涂油会破坏钝化膜结构,反而使镀锌板耐盐雾腐蚀性能降低。

Through neutral salt spray test,this study systematically explored the influence of zinc layer morphology and post-treatment methods on the corrosion resistance of galvanized sheet.The results show that the morphology of the zinc layer has a great influence on the corrosion resistance of the galvanized sheet,because the morphology of the zinc flower will increase the surface roughness of the galvanized sheet,resulting in a large actual effective area of the galvanized sheet in contact with the corrosive medium in the salt spray box.At the same time,the second phase particles segregated on the surface of the zinc layer form cathode activation points,promote the electrochemical reaction,and accelerate the corrosion rate;Oiling is a physical isolation and anti-corrosion measure.A large amount of water mist in the salt spray box will wash away the antirust oil coated on the surface of the galvanized sheet,which cannot protect the zinc layer,the galvanized sheet treated by this method has the worst anti-corrosion performance.Passivation treatment will form a continuous,water-insoluble and dense protective layer on the surface of zinc layer to inhibit the anodic reaction in electrochemical corrosion.The passivation plate with passivation treatment has the best salt spray corrosion resistance.Painting oil after passivation will destroy the structure of passivation film,but reduce the salt spray corrosion resistance of galvanized sheet.