氟盐-氧化物体系熔盐电解沉积Al-Cu-Y合金基础研究

The theme of research project is preparing for Al-Cu-Y alloy by molten salt electrolysis in the fluoride salt-oxide system. First, the basic physical and chemical properties(such as density, viscosity, electrical conductivity) of AlF3-(Li,Na)F-(Al2O3-CuO-Y2O3) system and the solubility and dissolution mechanism of Y2O3 will be studied systematically. Second, the transmission rule and kinetic parameters of active material, the deposition process and alloying mechanism of active ion, especially the electrode reaction mechanism of Y (Ⅲ) ion, will be investigated by electrochemical technology, such as potential scan, step pulse, impedance analysis method. Thirdly, the distribution of electric field(anode, liquid cathode and electrolyte) of electrolytic cell (200A grade for laboratory) will be surveyed by numerical simulation method. The regulatory mechanism of composition and impurities of Al-Cu-Y alloy in the process of electrolytic, and dissolved loss and secondary role of alloy product in the melt, will be studied systematically and seriously. The purpose of research project is providing the theory basis and technical prototype for preparing of Al-Cu-Y alloy by molten salt electrolysis in the fluoride salt-oxide system.

本项目拟采用氟盐-氧化物体系熔盐电解沉积制备Al-Cu-Y合金，在研究AlF3-(Li,Na)F-(Al2O3-CuO-Y2O3)体系的密度、粘度、电导率等基本物理化学性质变化规律，重点掌握Y2O3的溶解度及溶解机理基础上，运用电位扫描、阶跃脉冲、阻抗等电化学技术分析和揭示体系在电解过程中活性物质的传输规律及动力学参数、活性金属离子的沉积过程及合金化机理，特别是Y(Ⅲ)离子电极反应机制。对实验室200A级小型电解槽的上插阳极、液态下阴极及电解质的电场分布进行数值模拟。重点研究电解过程中Al-Cu-Y 合金产物成分、杂质的调控机制，以及在熔体中的溶解损失和二次作用。为氟盐-氧化物体系电解制备Al-Cu-Y合金提供理论基础和技术原型。

稀土元素 Y能够显著提高Al-Cu 系合金的耐腐蚀性能，而熔盐电解法制备稀土合金具有流程简单、稀土回收率高且环境友好等优点，因此，探索氟化物-氧化物体系下电还原制备Al-Cu-Y三元合金的方法具有重要意义。本项目研究AlF3-(Li,Na,Mg)F-(Al2O3-CuO-Y2O3)体系下电解制备Al-Cu-Y合金，内容涵盖体系的基本物理化学性质及活性金属离子电极还原过程的热力学及动力学机理；模拟计算电解过程中电解槽的电场、流场分布及耦合作用；解析电解合金产物中组分及杂质的调控机制。结果表明：Y2O3与介质的氟化作用是活性Y(III)离子的主要来源，其析出电位与体系内活性离子的析出电位接近，Al(Ⅲ)、Cu(Ⅱ)活性离子的阴极还原优先完成，均为一步完成电子转移过程，形成的Al-Cu合金层能够正移活性Y(III)离子电位，经还原及合金化最终形成Al-Cu-Y合金。在温度935℃及电流密度0.7A/cm2条件下，形成的合金基体为Al，合金中Cu和Y的含量可分别控制在3-5wt%和0.1-0.3wt%范围内，Cu和Y主要分布在晶界上，形成金属间化合物主要是Al2Cu相和Al3Y相，可显著改善合金的综合性能。本项目研究结果能够对氟盐-氧化物体系电解制备Al-Cu-Y 合金提供基础理论数据及指导。