| 摘要 |
PURPOSE:To form a Zn-precipitated layer suitable for forming a Zn-diffusion layer having strong corrosion resistance to the surface of an Al-material, by allowing the Al-material to which pretreatment is applied to perform Zn-substituting reaction by immersing the same in an aqueous ZnF2 solution. CONSTITUTION:An Al-material to which pretreatment such as degreasing is applied according to a usual method is immersed in an aqueous ZnF2 solution and kept at a proper bath temp. to be allowed to perform Zn-substituting reaction and a Zn-precipitated layer is formed on the surface of the Al-material. By this method, the Zn-layer precipitated by heating in a post-process is diffused into the Al-material from the surface thereof to form a Zn-diffused layer which in turn acts as the sacrifice anode to the Al-material. Therefore, corrosion, especially, pitting corrosion of the Al-material is effectively prevented.
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