黎敏,董妮妮,潘明,王保勇,王长成,邵蓉,刘武华,刘永壮.典型汽车用镀锌板耐腐蚀性能研究[J].表面技术,2023,52(4):295-303, 318.
LI Min,DONG Ni-ni,PAN Ming,WANG Bao-yong,WANG Chang-cheng,SHAO Rong,LIU Wu-hua,LIU Yong-zhuang.Corrosion Resistance of Typical Galvanized Plate for Automobile[J].Surface Technology,2023,52(4):295-303, 318 |
| 典型汽车用镀锌板耐腐蚀性能研究 |
| Corrosion Resistance of Typical Galvanized Plate for Automobile |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.04.026 |
| 中文关键词: 镀锌板 循环腐蚀 附着力 大气腐蚀 |
| 英文关键词:galvanized sheet cyclic corrosion adhesion atmospheric corrosion |
| 基金项目: |
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| Author | Institution |
| LI Min | Research Institute of Technology of Shougang Group Co., Ltd., Beijing 100041, China |
| DONG Ni-ni | Shougang Jingtang United Iron and Steel Co., Ltd., Hebei Tangshan 063200, China |
| PAN Ming | Shougang Jingtang United Iron and Steel Co., Ltd., Hebei Tangshan 063200, China |
| WANG Bao-yong | Shougang Jingtang United Iron and Steel Co., Ltd., Hebei Tangshan 063200, China |
| WANG Chang-cheng | Shougang Jingtang United Iron and Steel Co., Ltd., Hebei Tangshan 063200, China |
| SHAO Rong | Research Institute of Technology of Shougang Group Co., Ltd., Beijing 100041, China |
| LIU Wu-hua | Shougang Jingtang United Iron and Steel Co., Ltd., Hebei Tangshan 063200, China |
| LIU Yong-zhuang | Research Institute of Technology of Shougang Group Co., Ltd., Beijing 100041, China |
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| 中文摘要: |
| 目的 汽车用镀锌板电泳漆膜遭到破坏后的耐膜下扩蚀性能。方法 采用SEM、GDS、XPS、电化学工作站研究了3种典型镀锌板GA、GI、ZM的镀层结构。采用循环盐雾试验、大气暴露试验研究了电泳前3种镀锌板的耐腐蚀性。采用循环盐雾试验研究了3种镀锌板电泳后的耐腐蚀性能。结果 GI板和ZM板表面光滑平整，仅可见部分光整坑，表面存在较多Al的氧化物，ZM板表面存在较多Mg的氧化物，GA板镀层含有10%左右的Fe，表面由于含有ζ相和δ相，小孔洞较多。涂装前ZM耐腐蚀性优于GI和GA材料。ZM镀层中含有电位较负的二元共晶相MgZn2，在腐蚀过程中，MgZn2优先发生腐蚀，由于阴极氧还原产生大量的OH‒会导致镀层表面pH值升高，优先溶出的Mg离子可以抑制镀层表面薄液膜碱化，而较低的pH值可以促进保护性镀层Zn5(OH)8Cl2.H2O的生成，氧在其表面的还原速率较低，对镀层有一定的保护。GA和ZM材料涂装后的耐蚀性均优于GI材料，二者机理存在一定区别。GA板表面晶粒一般呈粒状或者长柱状或者两者皆有，其结构起伏明显多于GI板，电泳液固化前可以充满镀层表面的小孔洞或者柱状晶粒间的缝隙，固化后在电泳漆膜和镀层之间产生了类似“榫卯结构”的机械作用力，电泳膜附着力较强。故GA板涂装后的耐蚀性较好;而ZM镀层对基体Fe的电化学保护作用较好，阴极氧还原速率较慢，故其涂装后耐膜下扩蚀能力较好。结论 ZM板具有优良的涂装后耐腐蚀性能，在车身防腐等级要求较高的部位具有广泛的应用前景。 |
| 英文摘要: |
| The corrosion resistance of the electrophoretic paint film of galvanized sheet for automobile after being damaged is the key to the anticorrosion of the whole automobile. The coating structures of three typical galvanized sheets GA, GI and ZM were studied by SEM, GDS, XPS and electrochemical workstation. The corrosion resistance of three galvanized sheets before electrophoresis was studied by cyclic salt spray test and atmospheric exposure test, and the corrosion resistance of three galvanized sheets after electrophoresis was studied by cyclic salt spray test. The surfaces of GI plate and ZM plate are smooth and flat, only part of the polished pits can be seen, and there are more Al oxides on the surface, more Mg oxides on the surface of ZM plate, and about 10% Fe in the coating of GA plate. Because of the ζ phase and δ phase, there are many small holes on the surface, and the hardness of ZM coating is higher than that of GI coating. The corrosion resistance of ZM before coating is better than that of GI and GA materials. The atmospheric corrosion results show that at 24 months, the corrosion weight loss of GI is greater than that of GA, and that of GA is greater than ZM, and the weight loss of GI is about 3 times that of ZM, which corresponds to the results of cyclic salt spray. This is because the ZM coating contains binary eutectic phase MgZn2 with negative potential. During the corrosion process, MgZn2 preferentially corrodes, because a large amount of OH‒ generated by cathodic oxygen reduction will lead to an increase in the pH value of the coating surface. The preferentially dissolved Mg ions can inhibit the alkalization of the thin liquid film on the coating surface, while the lower pH value can promote the formation of the protective coating Zn5(OH)8Cl2.H2O, and the reduction rate of oxygen on the surface is low, which has certain protection for the coating. The corrosion resistance of GA ZM and GA ZM materials after coating is better than that of GI materials, and there is a certain difference between the two mechanisms. The grains on the surface of GA plate are generally granular or long columnar or both, and the structural fluctuation of GA plate is obviously more than that of GI plate. Before curing, the electrophoretic solution can fill the small holes or gaps between columnar grains on the surface of the coating. After curing, a mechanical force similar to "tenon and mortise structure" is generated between the electrophoretic paint film and the coating, and the electrophoretic film has strong adhesion. Therefore, the corrosion resistance of coated GA board is better than that of GI. However, ZM coating has a good electrochemical protection effect on matrix Fe, and the reduction rate of cathode oxygen is relatively slow, so its corrosion resistance under the coating is better than that of GI. ZM plate has excellent corrosion resistance after coating, and it has a wide application prospect in the parts with high requirements for anti-corrosion grade of automobile body. |
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