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分析了电解剥离过程中热镀锌合金化镀层的阳极溶解机制。结果表明,在GA镀层电解剥离的初始阶段,主要发生Zn的氧化,电解剥离过程中存在Zn和Fe之间的电耦合反应。由于镀层中微裂纹的存在,阴极反应区和镀层裂纹缝隙中会同时发生析氢反应,从而导致电偶腐蚀发生并形成诱导电流。当电解质溶液中存在氯离子时,Zn和Fe之间也会发生电耦合反应,该反应可以在一个非常小的局部区域内进行,反应过程中,氢的形核析出既可以是氢离子的重组,也可以是少量Zn和Fe的溶解反应。GA镀层中Fe-Zn金属间化合物同时发生电化学反应而溶解的现象只能在缝隙中发生,由于细小缝隙表面形成的活化区非常小,因此,GA镀层中的Fe-Zn相将分别发生溶解,从而保证了GA镀层中不同相之间的电压跃迁。
The anodic dissolution mechanism of hot dip galvanized alloying coatings during electrolytic stripping was analyzed. The results showed that the oxidation of Zn mainly occurred in the initial stage of electrolytic stripping of GA coating, and there was an electric coupling reaction between Zn and Fe in the process of electrolytic stripping. Due to the presence of micro-cracks in the coating, the hydrogen evolution reaction occurs simultaneously in the cathode reaction zone and the coating crack gap, resulting in the galvanic corrosion and the formation of induced current. When chloride ions are present in the electrolyte solution, an electrical coupling reaction between Zn and Fe occurs and the reaction can take place in a very small localized area. During the reaction, the nucleation of hydrogen can either be a recombination of hydrogen ions , But also a small amount of Zn and Fe dissolution reaction. The phenomenon that the Fe-Zn intermetallic compound in the GA coating is electrochemically reacted and dissolved at the same time can only occur in the gap. Due to the very small activation area formed on the surface of the fine gap, the Fe-Zn phase in the GA coating dissolves , Thus ensuring the voltage transition between the different phases in the GA coating.