水溶液中电沉积Zn-Ni-RE合金的工艺研究及机理分析

【作者】 李付绍；

【导师】 张英杰；

【作者基本信息】 昆明理工大学 ， 冶金物理化学， 2004， 硕士

【摘要】 本文研究了水溶液中电沉积Zn-Ni-RE合金镀层的工艺及其合金共沉积机理，主要包括以下几个方面： 通过查阅文献，总结前人关于电沉积稀土及稀土合金的科研成果之后发现，水溶液中电沉积稀土及稀土合金在实践上已经迈出了一大步，理论上也给予了相应的解释，提供了从水溶液中电沉积Zn-Ni-RE合金的可能性。而且，文献报道从水溶液中电沉积出稀土及稀土合金，必须寻找合适的配合剂（或络合剂）及合适的工艺规范才有利于稀土的沉积，本实验中找到了合适的配合剂电沉积Zn-Ni-RE合金。 确定了Zn-Ni-RE合金电沉积工艺的体系及最佳工艺规范。考察了各种因素对镀层的影响，发现镀液中稀土主盐的浓度是影响Zn-Ni-RE合金镀层中稀土含量最主要的因素，稀土盐LaCl₃的添加有利于提高镀层稀土的含量，而且，发现在特定的工艺规范下，镀液中稀土的浓度只有达到某个临界值后，它才开始沉积，另外，添加剂和配合剂对Zn-Ni-RE合金镀层的成分影响也很大，镀液中加入添加剂有利于提高镀层中稀土的含量，其它因素对镀层的影响也较大。 研究了Zn-Ni-RE合金的耐蚀性，结果表明，Zn-Ni-RE合金镀层无需钝化即具有较高的耐蚀性。在5％NaCl溶液中以及在中性盐雾（NSS）试验中，Zn-Ni-RE合金镀层的耐蚀性要明显高于Zn-Ni合金镀层。 研究讨论了Zn-Ni-RE合金共沉积的机理，首次提出了“添加剂阴极吸附层辅助稀土离子还原”机理的假设，并从阴极／溶液界面结构的角度建立了添加剂辅助稀土离子还原时的“四电层”模型，并运用该模型对镀液中加入添加剂能提高镀层稀土含量的实验现象进行了解释。更多还原

【Abstract】 In this thesis, the process of electrodeposition of Zn-Ni-RE alloy from aqueous solution and its mechanism of co-deposition have been discussed in detail. It covered the following aspects:Concluded from former researchers’ work, electrodeposition of Rare Earth and rare-earth alloy from aqueous solution has been effected. Its mechanism has also been interpreted in theory. Therefore, electrodepostion of Zn-Ni-RE alloy from aqueous solution is possible. Meanwhile, complex chemistry of Rare Earth introduced in the solution to adjust electrode potential is a key issue for the process. In this process, a suitable complex chemistry has been attained.The solution’s optimized composite and process’ operating conditions have been determined. It was shown through research for electrodeposition of Zn-Ni-RE that different solution composite and different operating conditions can give rise to content of RE in coating. Main salt of RE is a most influential factor that affects content of RE in coating. Particularly it is shown that, only after concentration of main salt RE in solution succeeded a certain value, co-deposition of RE with Zn-Ni can be effected. Another interesting phenomenon is that addictive introduced into solution can greatly affect the content of RE in coating. Some other factors’ influences to content of coating’s composite have also been respectively shown.Zn-Ni-RE’s anti-corrosion performance has been studied. The result is that Zn-Ni-RE coating’s anti-corrosion performance is ideal even without being treated by chromate. In 5% sodium chloride neutral solution and under neutral salt spray, Zn-Ni-RE alloy coating’s anti-corrosion is obviously better than Zn-Ni alloy coating with equal thickness.Mechanisms of Zn-Ni-Re’s co-deposition have been discussed. Particularly, mechanism of "Rare Earth ion’s deoxidization with auxiliary of cathode surface’s additive’s absorbates-formed layer" is put forward for the first time by the author, and, in order to explain this mechanism, a model of’electrical four layer’ has been shown in detail from aspect of structure of cathode/solution’s interface.更多还原