镀层厚度对热镀锌热轧板耐蚀性的影响

Effect of Coating Thickness on Corrosion Resistance of Hot Galvanized Plate

为模拟热镀锌板的实际使用情况,以剪裁后不同镀层厚度的热镀锌热轧板为研究对象,采用光学显微镜(OM)观察镀锌前后基体组织,通过中性盐雾试验分析镀层厚度对热镀锌热轧板产生白锈和红锈的影响规律。结果表明:在腐蚀过程中,腐蚀沿镀层由四周向内部扩展,同时由钢基体向表面扩展和锌层表面向内部扩展;随着镀层厚度增加,腐蚀扩展时间增长导致腐蚀时间增长,热镀锌板抗白锈能力增强,意味着耐蚀寿命增加;但抗白锈能力与镀层厚度呈非线性关系,涂层较厚时,通过增加镀层厚度提高热镀锌板抗白锈能力的效率降低。

For simulating the actual usage of galvanized plates,using the clipped hot galvanized plates with different coating thickness as subjects,the structures of plate substrate before and after galvanization were observed by optical microscope （OM）,and the influencing mechanism of coating thickness on white rust and red rust of galvanized plates was analyzed by salt spray experiment.Results showed that during the corrosion process,the corrosion extended from surrounding to the internal,from the matrix of steel to the surface and from the zinc layer surface to the internal.With the increase of coating thickness,the longer expansion time of corrosion caused longer corrosion time,leading to the stronger ability of resisting white rust of galvanized plates,which indicated that the corrosion resistance life was improved.However,the relationship between the corrosion resistance life and coating thickness was nonlinear,and when the coating was too thick,the efficiency of improving corrosion resistance life was decreased by increasing coating thickness.