氟化物熔盐电解法制备Al-Sc合金过程超声协同机制研究

Al-Sc alloys have excellent properties with important applications in air-space industry, advanced traffic system and defense equipment. These materials may also have potential for upgrade metal products for aluminum industries. However, the potential of these alloys is limited by high-cost manufacturing processes, uneven distribution of Sc and low metal recovery rate. This proposal is aimed to use ultrasound-aided molten salt electrolysis to make Al-Sc alloys with research focus to two scientific problems 1) interfacial reactions and quality control methods, and 2) cathode process of the alloys formation and current efficiency. Multiple applications of electrochemical analysis, microstructure characterization and other techniques as well will be applied in this investigation. Emphasis is placed in better understanding of the mechanism of Sc/Zr electrochemical precipitations and their control steps, and the relationship between these reactions originated at the molten salt - liquid Al interface and the mass transfer of Sc/Zr containing particles, so that a new control methodology can be established to make homogenous alloys using ultrasound aided electrolysis. Through reducing metals loss from possible cycling of Al/Zr in the process and formation of frozen molten salt on thee cathode area, a high efficient reaction control will be tried to increase the current efficiency and metals recovery rate. Finally, a synergic optimization among the electrolysis parameters (temperature, current density, electrical decomposition potential, electrolyte composition, etc) and ultrasound parameters (frequency, intensity, duration, input method, etc) will be conducted to develop a technology protocol of producing high quality homogenous Al-alloy with lower production costs and higher metal recovery.

Al-Sc合金性能卓越，对发展航空航天、先进交通和国防装备中高品质轻量化材料、助力铝工业产品升级具有重要意义。针对现有工艺成本高、合金成分不均匀、效率低等技术瓶颈，本项目凝练出超声协同熔盐电解过程1）界面反应及超声调控机制、2）合金阴极过程动力学超声强化机制两个科学问题，综合运用多种电化学、显微分析等方法，阐明Sc/Zr析出反应机理及控制步骤，解析源于表界面初始析出相反应-耦合传输方式所致终态Sc偏聚现象，通过精确施加超声协同作用获得均匀调控合金成分的新机制；抑制Al、Sc金属循环和阴极冷壳层的危害，构建高效率、低成本制备Al-Sc合金的反应模式；协同优化控制电解工艺参数（温度、电流密度、分解电压、电解质组成等）与超声参数（频率、强度、周期、施加方式等），破解合金中Sc分布不均匀的技术瓶颈，形成一种低成本、高均质Al-Sc合金可控制备的新工艺基础及技术原型。

Al-Sc合金性能卓越，对发展航空航天、先进交通和国防装备中高品质轻量化材料、助力铝工业产品升级和高端制造具有重要意义。本项目针对现行工艺流程长、效率低、成本高及合金成分不均匀等技术瓶颈,研究了稳态条件下超声协同氟化物熔盐电解制备Al-Sc合金反应过程Sc2O3浓度、电解时间、操作温度等工艺因素的影响规律，系统阐明了超声协同对不同合金基体Al-M-Sc（M=Mg，Zn, Li, Cu, Si）中Sc扩散传质、Sc含量分布的动力学作用机制；综合采用SEM-EDX、XRD、TEM等分析手段，结合硬度、强度、断裂等力学测试，系统阐明了Al3Sc初晶相、W相强化和细化作用及超声协同机制，加深了对熔盐电解-熔炼凝固工艺制备多元铝基体系中Al3Sc、AlSi2Sc2相和W相形成、相互作用和微观结构演变规律的认知，并揭示出超声协同电解制备二元和三元含钪相铝基合金材料的力学性能强化机制。通过控制电解工艺参数（1037K、2wt%Sc2O3、合理电解周期、1A/cm2电流密度等）以及熔炼凝固速率，施加超声协同作用消除源于表界面初始析出相所致电解槽底部Sc偏聚现象，获得了成分均匀和组织可控的样品合金；在多元铝基体上熔盐电解制备Al-M-Sc合金过程中，借助超声协同强化Sc还原，提升合金中Sc含量和电流效率，改善了合金组织结构和力学性能。研究成果为发展低成本、短流程冶金材料一体化制备Al-Sc合金新工艺原型提供了科学基础和技术参数。