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采用真空蒸镀技术在镀锌钢板上蒸镀镁,制得了蒸镀镁层,将其在5%NaCl溶液中浸泡,运用XRD,SEM和电化学方法等对其腐蚀产物进行了分析。对2种材料的的腐蚀行为进行了研究,探讨了其耐腐蚀机理。结果表明:镀锌钢板蒸镀镁层是以MgZn2和Mg2Zn11金属间化合物的形式存在;其腐蚀产物是以致密且具有良好绝缘性的ZnCl2.4Zn(OH)2.H2O和致密的Zn4CO3(OH)6.H2O为主体,而纯锌镀层的腐蚀产物是以疏松且具有N型半导体性质的ZnO为主体;蒸镀镁层的形成可以抑制Zn(OH)2向ZnO的转化,能促进Zn(OH)2向ZnCl2.4Zn(OH)2.H2O和Zn4CO3(OH)6.H2O的转化,后二者能够牢固地覆盖在基体表面,从而延缓了锌的腐蚀进程;在宏观上表现为镀锌钢板蒸镀镁层腐蚀产物相对于纯锌镀层更加致密,在电化学行为上表现为镀锌钢板蒸镀镁层具有更小的腐蚀电流和更高的极化电阻。
Magnesium was deposited on the galvanized steel by vacuum evaporation. Magnesium was deposited on the galvanized steel and immersed in 5% NaCl solution. The corrosion products were analyzed by XRD, SEM and electrochemical methods. The corrosion behavior of two kinds of materials was studied and the corrosion resistance mechanism was discussed. The results show that the Mg layer deposited on the galvanized steel is in the form of MgZn2 and Mg2Zn11 intermetallic compounds. The corrosion products are dense and well-insulated ZnCl2.4Zn (OH) 2.H2O and dense Zn4CO3 (OH) 6.H2O as the main body, and the pure zinc coating corrosion products are loose and has the nature of the N-type semiconductor ZnO as the main body; deposited magnesium layer can inhibit the conversion of Zn (OH) 2 to ZnO, can promote Zn (OH ) 2 to ZnCl2.4Zn (OH) 2.H2O and Zn4CO3 (OH) 6.H2O conversion, the latter two can firmly cover the surface of the substrate, thus slowing the process of zinc corrosion; macroscopically showed galvanized steel Evaporation of magnesium layer corrosion products relative to the pure zinc coating more compact, the electrochemical behavior of galvanized steel vapor deposition magnesium layer has a smaller corrosion current and higher polarization resistance.