镍铁尖晶石基金属陶瓷惰性阳极的电解腐蚀行为

采用粉末冶金法制备了10%Ag-NiFe2O4/NiO金属陶瓷惰性阳极，阳极为圆柱形，直径50 mm，高15 mm. 在960℃下进行电流密度为0.8 A/cm2的铝电解实验，电解时间为10 h. 研究了阳极在Na3AlF6-5%CaF2-5%Al2O3熔体中的腐蚀行为. 电解后的阳极外观尺寸略有变化，但没有发生阳极肿胀及阳极表面起层、剥离的现象，表现出较好的耐腐蚀性. 计算得到阳极腐蚀率为1.5′10-4 g/(cm2·h)，折算为13 mm/a. 电解所得铝的纯度在92%~93%之间. 对腐蚀后阳极的表面分析发现，陶瓷相中Ni和Fe组元并不以化学计量数溶解，陶瓷组元的Fe2O3比NiO优先溶解进入电解质. 正对阴极的阳极表面和背对阴极的阳极表面氧元素的含量不同，前者中氧元素多于后者，说明在阳极正对阴极的表面发生析氧反应更剧烈一些，一部分新生态的氧与阳极表面的金属发生氧化反应生成Ag3O4. 对腐蚀后阳极断面进行分析发现，电解质渗透进入阳极内部，与陶瓷基体离解产生的Fe2O3发生反应，生成FeF3沉积在阳极的空隙中.

Electrolysis Corrosion Behaviour of NiFe2O4-based Cermet Inert Anode

A cermet inert anode of 10%Ag-NiFe2O4/NiO was prepared by powder metallurgical method. The inert anode is a cylinder with 50 mm height and 50 mm diameter. It was applied to aluminium electrolysis testing for 10 h at 960℃ and the current density of 0.8 A/cm2. The behavior of inert anode for aluminium electrolysis in Na3AlF6-5%CaF2-5%Al2O3 was studied. After 10 h electrolysis, the anode was slightly corroded. It was in good condition without tumescence and scaling, which shows that the anode has good corrosion resistance to molten cryolite-based melt. The corrosion rate of the anode was estimated as about 13 mm/a and the purity of the deposited aluminium was 92%~93%. The surface of the inert anode was analyzed using energy-dispersive X-ray microanalysis. The results indicate that non-stoichiometric dissolution of the oxide phase occurred, and Fe2O3 dissolved prior to NiO and entered the electrolyte. The content of oxygen on the surface of the inert anode facing to cathode was more than that of the other side, which indicates that the reaction of O2 releasing is more acute between the two electrodes. A part of released O2 reacted with Ag on the surface of inert anode to produce Ag3O4. The section of the inert anode was also analyzed. It was found that the electrolyte penetrated into the inert anode and reacted with Fe2O3, then the product FeF3 deposited in the interspaces in the anode.