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采用热浸镀方法在建筑用Q235钢面制备了55Al-43Zn-2Si镀层,研究了表面镀层的显微形貌、物相组成和耐腐蚀性能。结果表明,Q235钢板基材表面镀层较为平整,无明显凹凸,局部区域存在分散的显微凹陷或针孔;经过热浸镀处理后镀层已经覆盖Q235钢表面,表面镀层中只有Al和Zn相,且灰黑色区域是富Al相,灰白色区域为富Zn相;在Q235钢镀层腐蚀时镀层表面灰白色富Zn相优先腐蚀,随后才发生富Al相和化合物相的腐蚀,最终造成腐蚀介质渗漏而造成Q235钢基体的腐蚀破坏。
The 55Al-43Zn-2Si coating was prepared on Q235 steel for construction by hot-dip method. The microstructure, phase composition and corrosion resistance of the surface coating were studied. The results show that the surface coating of Q235 steel substrate is flat, with no obvious irregularities. There are scattered micro-depressions or pinholes in the local area. After hot-dip coating, the surface of Q235 steel is covered with Al-Zn coating. And the gray-black region is Al-rich phase and the gray-white region is Zn-rich phase. When the Q235 steel layer is corroded, the gray-white Zn-rich phase is preferentially corroded, and then the Al-rich phase and the compound phase corrode, leading to leakage of the corrosive medium Corrosion caused by Q235 steel substrate damage.