室温离子液体中铀表面Al-Mn镀层电沉积反应机制的原位研究

Ionic liquid electrodeposition technology is an important development direction in the field of uranium surface modification. The Al-Mn coating electrodeposited from ionic liquids has excellent anti-corrosion and mechanical properties, but the lack of understanding its electrodeposition mechanism limits the widespread application. It is difficult to obtain the electrodeposition mechanism of near-overpotential alloys such as Al-Mn relying on traditional electrochemical methods. Besides, the interaction between uranium and ionic liquids makes the reaction mechanism more complicated. In this study, the in-situ SEM/EDX technique combined with spectrum and electrochemical methods will be used to clarify the electrodeposition mechanism of Al-Mn coating from EMIC-AlCl3-MnCl2 room temperature ionic liquids. Meanwhile, the compatibility behavior of uranium and ionic liquids will also be studied to further establish the influence of uranium on the electrodeposition process. On this basis, the component prediction model of Al-Mn will be developed under the correction of reaction equations, surface concentrations and reaction rate constant. Furthermore, The mapping between coating properties and electrodeposition parameters will be established and the precise control method of Al-Mn coating properties on uranium surface can be obtained. This study will lay the foundation for the realization of all uranium component, whole life cycle, and all-weather protection.

离子液体电沉积技术是铀表面改性领域的重要发展方向。离子液体电沉积Al-Mn镀层性能优异，但对其电沉积反应机制认识的不足制约着铀表面Al-Mn镀层厚度及性能的精确控制，是阻碍其应用的本质肇因。依托传统的电化学研究手段难以获得Al-Mn这类近过电位合金的电沉积反应机制；并且，铀与离子液体的相互作用会使得其表面电沉积反应机制更为复杂。本研究中拟依托原位SEM/EDX技术研究室温离子液体中Al-Mn电沉积界面反应物的扩散动力学特性，进一步联用光谱技术、电化学技术阐释Al-Mn电沉积反应的机制；同时，拟研究铀与离子液体的相容行为，进一步探究铀对Al-Mn电沉积过程影响的机理；在此基础上，从反应方程、表面浓度、反应速率常数三个方面修正既有的成分预测模型，并完善Al-Mn镀层性能与晶体结构、晶体结构与成分的规律性认识，建立镀层性能与电沉积参数的映射，发展出铀表面Al-Mn镀层厚度与性能的精确控制手段。

针对铀表面低温高质量铝基镀层的制备需求，本研究系统开展了EMIC-AlCl3-MnCl2室温离子液体中Al-Mn的电沉积机制及镀层性能影响因素研究。首先，通过光谱、电化学方法等联用的方法重点研究了EMIC-AlCl3-MnCl2室温离子液体中Al-Mn的电沉积反应机制，获得了EMIC-AlCl3-MnCl2室温离子液体中的主要离子种类及组成；进一步结合电化学手段明确了电化学反应方程，获得了反应的动力学特性及控制步骤。其次，基于电化学石英微晶天平等技术手段，获得了沉积过程中Al-Mn的起始沉积电位、极限电流密度等关键动力学特性，计算出扩散层厚度差异。通过表征浸泡实验后铀与离子液体的成分与结构变化，获得了铀与离子液体的相容性；明确了铀的表面状态以及离子液体的组成是影响两者相容性的主要因素。此外，发现了铀与离子液体的置换反应主要受两者氧化还原电位差异的驱动，且该置换过程的速率控制步骤主要为界面处吸附层对基体的钝化效应，并基于此发展出了置换抑制方法。最后基于反应方程及动力学特性，结合传质过程扩散、电迁移、对流过程的解析，导出反应速率的数学表达；通过引入修正参数k更新了成分预测模型，并验证了新模型对于成分预测的准确度更高。本研究拓展、完善Al-Mn镀层的成分-结构-性能构效关系，为面向性能的电沉积工艺过程设计奠定基础。