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采用热浸镀的方法在镀锌模拟器上制备得到纯Zn、Galfan和Zn-Al-Mg 3种锌合金镀层钢板,3种镀层中的合金元素质量分数分别为Zn-0.2%Al,Zn-5%Al和Zn-2%Al-2%Mg,镀层钢板为无间隙原子钢(IF钢)。采用全浸泡的方法研究了3种锌基合金镀层钢板的腐蚀行为,并采用电化学方法和扫描电镜研究了浸泡不同时间的锌基合金镀层钢板的耐蚀性。结果表明,在浸泡初期,Zn-Al-Mg镀层钢板的自腐蚀电流密度最大;随着浸泡时间延长,Zn-Al-Mg镀层钢板的自腐蚀电流密度缓慢减小,而纯Zn镀层钢板和Galfan镀层钢板的自腐蚀电流密度均增大。Galfan镀层钢板的Nyquist曲线具有明显扩散特征,镀层表面的腐蚀速率较快;而Zn-Al-Mg镀层钢板的Nyquist曲线表现为有限扩散特征,这表明其表面覆盖的腐蚀产物提高了Zn-Al-Mg镀层钢板的耐蚀性。
Pure Zn, Galfan and Zn-Al-Mg three kinds of zinc alloy coated steel sheets were prepared by hot-dip plating on galvanized simulators. The content of alloying elements in the three coatings were Zn-0.2% Al and Zn- 5% Al and Zn-2% Al-2% Mg. The coated steel plate is interstitial-free atomic steel (IF steel). The corrosion behavior of three kinds of Zn-based alloy coated steel sheets was investigated by immersion method. The corrosion resistance of the zinc-based alloy coated steel sheets immersed in different time was studied by electrochemical method and scanning electron microscope. The results show that the self-corrosion current density of Zn-Al-Mg coated steel sheet is the highest at the initial immersion time. With the immersion time, the self-corrosion current density of Zn-Al-Mg coated steel sheet decreases slowly. Self-corrosion current density of the coated steel increases. The Nyquist curve of Galfan coated steel has obvious diffusion characteristics and the corrosion rate of the coating surface is fast. The Nyquist curve of Zn-Al-Mg coated steel exhibits limited diffusion characteristics, which indicates that the corrosion products covered by the surface increase the Zn-Al- Corrosion resistance of Mg coated steel.