熔盐电解法制备V-4Cr-4Ti合金氧的迁移机制及产物合金化过程研究

The method of electrochemical reduction of solid metal oxides in molten salts provide a novel technology for preparation of V-4Cr-4Ti alloy as structure materials for nuclear reactor, which has the merits such as short process, low cost, low energy consumption, environment-friendly metallurgy etc. At present, low current efficiency is the main problem. On the other hand, research on electrochemical reduction mechanism and dynamic process for preparing alloy is also scarce. The project intends to add pore former and metal powder to improve microstructure and electrical conductivity of oxide electrode to enhance electrode activity. Adopting normal electrochemical method to study the electrochemical behavior and electrode process of vanadium oxides in high temperature molten salt, obtaining the processes of oxygen ion migration in electrode，molten salt，elecrtode/molten interface and charge transfer to illustrate the migration mechanism, at the same time obtaining the rate-determining step of the reaction, thus control the electrolysis process to enhance the electrolysis efficiency. Combine the physical and chemical method to study on the phase composition, microstructure and distribution of electrolytic products to inllustrate the alloying process. The first time, electrochemical in-situ raman spectroscopy technology was used in investigating the detailed structure and ion dynamic process on the electrode/molten salt interface, and furthermore to study oxygen ion migration law and solid transformation mechanism at molecular level, finally illustrate the electrochemical reduction mechanism and dynamic process in preparing vanadium based alloy.

熔盐电解固态化合物新方法为核反应堆用结构材料V-4Cr-4Ti合金的短流程、低成本、低能耗、绿色冶金制备开辟了新途径。目前合金制备电流效率低，合金形成的电化学还原机理及动力学过程研究匮乏。本项目拟通过添加造孔剂和金属粉，改善氧化物电极的微孔结构及导电性能，提高氧化物电极的活性。利用常规电化学方法研究含钒氧化物电极在熔盐中的电化学行为及电极过程，获得氧在电极、熔盐及电极/熔盐相际界面的迁移及电荷转移过程，弄清氧的迁移机制，得到反应的速控步骤从而控制电解工艺条件，提高整个电解过程的效率。结合材料物化表征手段分析电解产物的相组成、微观结构和界面物质分布，阐明产物的合金化过程。同时首次采用原位拉曼光谱电化学技术原位研究含钒氧化物电极/熔盐界面相结构变化和离子变迁过程，进一步从分子水平上研究氧的迁移规律和产物的固相转变机制，丰富钒基合金制备的理论，阐明钒基合金的电化学还原机理与合金制备的动力学过程。

V-4Cr-4Ti合金是核反应堆用重要的结构材料，熔盐电脱氧法制备金属及合金材料具有广泛的应用前景，为V-4Cr-4Ti合金的短流程、低成本、低能耗、绿色冶金制备开辟了新途径。目前缺乏钒合金电解制备过程中电化学还原机理，动力学过程电解工艺参数对电解制备过程的影响。. 本项目确定了硼化钨惰性电极粉体的合成和陶瓷致密化烧结的工艺条件，研究了硼化钨电极材料的力学及抗氧化性能。通过添加造孔剂获得了孔隙率为57%的V2O3-Cr2O3-TiO2混合氧化物电极，考察了孔隙率，电极微观结构，电解温度，电解电压对V-4Cr-4Ti电解制备过程的影响。. 采用循环伏安法等研究了V2O3，V2O3-TiO2，V2O3-Cr2O3，V2O3-Cr2O3-TiO2等氧化物在熔盐中的电化学行为，分析了电解工艺条件对电解产物形貌和成分的影响。确定了金属V，V-Ti，V-Cr，V-Cr-Ti合金在电化学制备过程中的中间产物，确定了合金组分在熔盐中的还原历程,析出顺序和合金化过程。采用原位拉曼光谱法结合循环伏安图谱研究了Na2CO3-K2CO3，Li2CO3-Na2CO3，Li2CO3-K2CO3熔盐体系在电化学反应过程中电极表面的熔盐原位拉曼光谱，确定了电化学反应过程中电极表面离子结构变化及迁移规律