锌铝镁合金镀层的组织及腐蚀性能研究综述

    Review on Microstructure and Corrosion Resistance of Zn-Al-Mg Alloy Coatings

    • 摘要: 锌铝镁合金镀层因优异的腐蚀性能、切口自修复性能和易加工性能,被广泛应用于电器、建筑、汽车和光伏等领域,有望成为新一代环保、低碳的战略性耐蚀性材料。综述了Al、Mg添加元素和组织对锌铝镁合金镀层性能的影响,包括富铝枝晶相、共晶组织和锌枝晶相对镀层裂纹扩展影响的研究,同时归纳了腐蚀产物的形成机理及其对合金镀层的保护机制。研究发现,阳极溶解的镁离子能缓冲腐蚀介质的酸碱性,诱导致密的锌盐沉淀物(Zn5(OH)8Cl2·H2O和Zn6Al2(OH)16(CO33·4H2O)形成,可进一步提升锌铝镁镀层的腐蚀性能。目前,关于锌铝镁合金镀层的腐蚀性能研究主要集中在低铝和中铝锌铝镁镀层,且腐蚀环境大多为C1~C4等级的大气腐蚀环境,而对于高铝锌铝镁合金镀层在更复杂的应用环境下的研究尚有不足,例如应力腐蚀环境或者C5以上等级的腐蚀环境。最后提出了锌铝镁合金镀层所面临的问题及发展展望。

       

      Abstract: Zinc-aluminum-magnesium alloy coatings are widely used in the fields of electrical appliances, construction,automotive and photovoltaic industries due to their excellent corrosion resistance, self-healing properties at cut edges and ease of processing. They are expected to become a new generation of environmentally friendly, low-carbon strategic corrosion-resistant materials. The effects of Al, Mg alloying elements and phase structures on the properties of zinc-aluminum-magnesium alloy coatings, including studies on the crack propagation process influenced by dendritic aluminum phases, eutectic structures and dendritic zinc phases,were reviewed. The formation mechanisms of corrosion products and their protective mechanisms on the alloy coatings were also summarized. It had been found that the anodically dissolved magnesium ions can buffer the pH of the corrosive medium, inducing the formation of dense zinc salt precipitates(Zn5(OH)8 Cl2·H2O and Zn6 Al2(OH)16(CO33·4H2O),further enhancing the corrosion resistance of the zinc-aluminum-magnesium coatings. Current research on the corrosion resistance of zinc-aluminum-magnesium alloy coatings mainly focused on low-aluminum and medium-aluminum zinc-aluminummagnesium coatings, with corrosion environments mostly being atmospheric conditions of C1 to C4 levels. However, there was insufficient research on high-aluminum zinc-aluminum-magnesium alloy coatings in more complex application environments, such as stress corrosion environments or corrosion environments above C5 level. Finally, the challenges faced by zinc-aluminum-magnesium alloy coatings and prospects for future development were presented.

       

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