| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 97 === Zn coating is better and cheaper than other metal coatings in resisting the Cl- ion corrosion, so it is widely used for protecting the steel tools which are working under seawater environment. Lately the coating methods like hot-dip galvanizing, electroplating and CVD/PVD by using vacuum furnace or fluidized bed are extensively applied in fabricating of Zn coating. But, it still exists some problems with cost, environment pollution, and workpiece measurement in continuous process by using these coating methods. Solid-diffusion coating method can form a continuous Fe-Zn outer layer in uniform thickness by controlling the process conditions. In this study, Zn coating is formed using solid-diffusion coating method by heating the substrate to 400℃ for 2 hours. The multi-layer films not only enhance the corrosion resistance and surface hardness, but also improve the recyclability and reusability of Zn powder by some specific repeated cycles. Although the addition of Al powder in Zn coating reduces the coating thickness, it improves the anti-corrosion property under alkaline environment. After electrochemical analysis, the Zn coatings made by solid-diffusion method reveal the best corrosion resistance and the highest corrosion potential under alkaline environment. So we can expect the Zn coating with lower corrosion probability to provide better sacrificed protection.
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