Aluminum Electroplating on AZ31 Magnesium Alloy with Acetic Anhydride Pretreatment
Aluminum Electroplating on AZ31 Magnesium Alloy with Acetic Anhydride Pretreatment
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DOI：
10.1007/s40195-022-01453-z
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Zelei Zhang;A. Kitada;Kazuhiro Fukami;K. Murase
中科院分区：
文献类型：
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作者：
Zelei Zhang;A. Kitada;Kazuhiro Fukami;K. Murase
用于金属电镀的镁合金需要进行表面处理，即去除表面自发氧化的层(氧化镁、氢氧化镁和碳酸镁)。然而，在传统的前处理工艺中使用剧毒和/或腐蚀性酸已成为一个问题。本研究提出了一种简便、低毒的前处理方法，并将其应用于铝电镀。AZ31镁合金在乙酸酐(Ac2O)中的浸泡去除了自发氧化的表面层，并形成了薄而稳定的醋酸镁(Mg(OAc)2)层，以保护金属衬底免受进一步氧化。铝电镀液是一种浓缩的二甘醇(G2)-AlCl3有机溶液，可以很容易地溶解镁(OAc)2，从而能够直接在金属衬底上电镀。镀态铝层具有致密无裂纹的形貌，提高了耐蚀性和硬度(2.7 Gpa)。由于没有界面氧化层，热处理导致了镁、铝原子的成功扩散，使硬度提高到4.4 GPa.通过对镁合金进行Ac2O前处理，可以成功地进行电镀铝和后续热处理。
Magnesium (Mg) alloys for metal electroplating require a surface pretreatment, i.e., the removal of the spontaneously oxidized surface layer (MgO, Mg(OH)2, and MgCO3). However, the use of highly toxic and/or corrosive acids in conventional pretreatment processes has become an issue. In this study, a facile and less toxic pretreatment is demonstrated and applied in aluminum (Al) electroplating. The immersion of the AZ31 Mg alloy into acetic anhydride (Ac2O) removed the spontaneously oxidized surface layer and formed a thin but stable magnesium acetate (Mg(OAc)2) layer that protects the metal substrate from further oxidation. The Al electroplating bath is a concentrated diglyme (G2)-AlCl3organic solution that can readily dissolve Mg(OAc)2to enable direct plating onto a metal substrate. The as-deposited Al layer has a compact and crack-free morphology that improves the corrosion resistance and hardness (2.7 GPa). Owing to the lack of an interfacial oxidized layer, heat treatment led to the successful diffusion of Mg and Al atoms, which increased the hardness to 4.4 GPa. The Ac2O pretreatment of Mg alloys enables the successful Al electroplating and subsequent heat treatment.