建筑用Q235钢的表面镀层与耐腐蚀性能研究

Surface Coating and Corrosion Resistance of Q235 Steel for Construction

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 the surface of the Q235 steel with hot dip plating method, the microscopic morphology, phase composition and corrosion resistance of coating was investigated. The results show that the coating on the surface of Q235 steel substrate is smooth, no obvious convex or concave, and dispersed micro pits or pinholes exist in the local area. The coating has been covering the surface of Q235 steel after hot dip plating, surface coating is only Al and zinc, and gray-black area is Al-rich phase, gray areas is zinc-rich phase; then Al and compound phase of corrosion, resulting in corrosion medium leakage caused by corrosion of Q235 steel substrate. The grey and white area for Zn rich phase of coating Q235 steel surface is corrosion firstly, and secondly, Al and its compound phase will be corrosion, lastly, the Q235 steel substrate will be corrosion and damaged with the leakage of corrosion liquid.