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用SEM和XRD观察和分析了铝含量和合金化时间不同的热镀锌合金化(GA)镀层的表面形貌和组织,用双杯突测量了GA镀层的抗粉化量。结果表明,锌液中铝含量小于0.16 mass%的热镀锌镀层合金化时,镀层表面的Ra值小于1.0μm,且镀层的粉化量小于30 mg/m2,满足汽车板的表面质量要求;此后随着锌液中铝含量的增加,GA镀层的粉化量迅速增加,说明GA镀层的抗粉化性能除与镀层中的铁含量有关外,还与镀层表面的粗糙度有关。锌液中铝含量为0.22 mass%热镀锌镀层合金化时,由于Fe2Al5Znx抑制层的抑制作用,镀层中的δ1k-相出现局部增多的现象,从而恶化了GA镀层的抗粉化性能。
The surface morphology and microstructure of hot-dip galvanized (GA) coatings with different aluminum content and alloying time were observed and analyzed by SEM and XRD. The anti-flaking amount of GA coating was measured by double-cup process. The results show that when the hot dip galvanized coating with the content of aluminum less than 0.16 mass% in the zinc solution is alloyed, the Ra value of the coating surface is less than 1.0μm and the powdering quantity of the coating is less than 30 mg / m2, which meets the surface quality requirements of the automobile plate. Since then, with the increase of aluminum content in zinc solution, the amount of powdered GA coating increased rapidly, indicating that the anti-pulping property of GA coating is related to the surface roughness of the coating in addition to the iron content in the coating. The content of aluminum in the zinc solution is 0.22 mass% When the galvanized coating is alloyed, the δ1k-phase in the coating locally increases due to the inhibition of the Fe2Al5Znx suppressing layer, thereby deteriorating the powdering resistance of the GA coating.