类核-壳型金属陶瓷包覆铝基/多元氧化物涂层电极材料的结构与性能研究

The electrode is the key material of nonferrous metal electrolysis, but the choice and preparation of electrode material is a difficult problem in hydrometallurgy industry. In this project, from the point of view of the selection and structural desigin of electrode material, the new design proposal of electrode structure is presented that the aluminum coated with cermet of TiB2 and Ti4O7 is selected as the substrate material with a core-shell like structure and the oxide Mn, Pb and Co is selected as the active coating. It is discussed that the substrate material is on the influences of the manufacturing process, the bonding condition of the interface and the microstructure evolution on the electrode reaction. The relationship between the coating composition and electrode performance is studied, meanwhile, based on the theory of thermodynamics and electrochemical kinetics, it is carried on sutudy that the micro-factors such as the coating composition, their solid solubility, grain size, surface roughness et al. is impact on the properties of surface fractal dimension, electrochemical kinetics and cyclic voltammetry. It is revealed that the effect of the formation mechanism of interface and the microstructure of coating is mechanism of action on the improvement of catalytic activity and the increase of service life. Based on the theory of the electrode process kinetics and thermodynamics, it is studied that the effecting law of the electron transmission way, electron transformation mechanism and the electric work function on the electrode potential and chemistry reaction speed during the electrolyzing reaction course is analyzed through a lot of tests. The key factor which the change of matrix material property is on the effect of the negative shift value of electro potential and saving enery saving has been recognized in hydrometallurgy.

电极是有色金属电解中的关键材料，其选择和制备是湿法冶金工业的难题之一。本项目将从电极材料的选择和结构设计入手，提出以导电好、耐蚀强的TiB2与Ti4O7金属陶瓷包Al为基体，以Mn、Pb、Co氧化物为活性涂层的类核-壳结构电极的设计方案。探讨制备合成过程、相界面分布以及其演变行为对电极反应的影响规律。考察涂层配比与电极性能的关系，并结合晶体学、电化学动力学，研究涂层的组织结构、固溶关系、晶粒大小、表面粗糙度等微观因素对电极的动力学参数、循环伏安特性、表面分形维数等的影响关系，揭示材料界面形成机制、涂层微观结构对提升电催化活性的作用机理。利用电极过程动力学、电化学热力学，研究金属陶瓷包覆Al基体材料的电子传输方式、转移机制和电子逸出功的改变对阳极过程电极电势、反应速度的影响规律，弄清基体材料性质的改变与电极极化电位负移，节省能耗的关键因素和作用规律。

本项目从电极材料的选择和结构设计入手，改变传统电极采用金属铅和钛作为基体的结构模式，制备了铝基多元涂层电极材料。首先分别采用轧制复合法、热压扩散焊接法和热喷涂等工艺制备了具有高效电子传输和活性物质转换的类核-壳型Al/TiB2+Ti4O7电极基体，其次在其表面用电沉积的方式，在复合基体上电沉积MOx(M=Pb、Mn、Ce)活性涂层，制备了如Al/TiB2+Ti4O7/PbO2、Al/TiB2+Ti4O7/PbO2+MnO2和Al/TiB2+Ti4O7/PbO2+CeO2等多种新型复合功能电极材料。最后采用MS和Comsol软件对材料进行了理论计算与仿真模拟，以期为界面结合和节能降耗提供理论支撑。. 采用热喷涂法制备制备Al/TiB2+Ti4O7电极基体时，先采用喷雾造粒得到团聚型复合粉体，随后分别研究了等离球化和烧结热处理对粉体的形貌和性能的影响，最后混合粉体在高温焰流的作用下沉积在Al基体表面，界面结合处无明显孔洞和裂纹，界面结合良好。通过对轧制复合法、热压扩散焊接法和热喷涂法所制备的复合基体性能对比，筛选出采用热喷涂法所制备的复合基体综合性能最佳。在电沉积过程中，在电流密度为0.03Acm-2时，当Mn2+和Ce3+含量分别为80g/L和1.5g/L时，所制备的PbO2+MnO2和PbO2+CeO2催化层活性和电化学性能最佳。在电积锌试验中，Al/TiB2+Ti4O7/PbO2+CeO2复合电极相比Pb基电极和Ti基电极，其槽电压较铅基电极下降70mV，较钛基电极下降200mV，电流效率较铅基电极高出3%，较钛基电极高出4%；能耗较铅基电极减168kWh/t，较钛基电极减少326kWh/t。采用MS模拟Al(111)/TiB2(0001)界面时，Ti终端中的心位界面具有最好的稳定性和结合强度。采用Comsol软件对阳极板表面电场分布情况表明，Al基复合电极板相比传统Pb合金电极其表面电流密度分布更为均匀。