铝电解用NiFe2O4-Cu金属陶瓷惰性阳极的制备

以高温固相合成法合成的NiFe2O4陶瓷粉体和金属Cu粉为原料, 采用冷压-烧结法制备了Cu含量在5%～20%之间的NiFe2O4-Cu金属陶瓷惰性阳极, 研究了烧结气氛和烧结温度对其物相组成、微观形貌和基本物理性能的影响. 结果表明 通过控制烧结气氛中氧分压在NiO和Cu2O的离解反应平衡氧分压之间, 可以制备出具有目标物相组成的NiFe2O4-Cu金属陶瓷; 烧结温度和保温时间对所得NiFe2O4-Cu金属陶瓷的相对密度有较大影响; NiFe2O4和Cu之间的不润湿性限制了NiFe2O4-Cu金属陶瓷烧结温度的提高和保温时间的延长, 在保证金属相分布均匀且不溢出的前提下, 所制备的NiFe2O4-Cu金属陶瓷的相对密度较小; 金属相Cu含量越高, NiFe2O4-Cu金属陶瓷最高烧结温度越低、最长保温时间越短, 从而相对密度越低、孔隙率越高; 除了尽量降低金属相含量外, 还可向NiFe2O4-Cu金属陶瓷中添加其他金属如Ni和Co等, 以改善陶瓷相与金属相之间的润湿性, 以提高烧结温度, 进而提高其相对密度和耐腐蚀性能.

Preparation of NiFe2O4-Cu based cermet inert anodes in aluminium electrolysis

NiFe_2O_4-Cu cermet inert anodes containing 5%20% Cu were prepared by cold pressing-sintering NiFe_2O_4 ceramic powder synthesized by solid state reaction and Cu metal powder. The effects of sintering atmosphere and temperature on the phase compositions, microstructure and morphology, physical properties of the cermet products were studied. The results show that the NiFe_2O_4-Cu cermet with the desired phase composition can be obtained by controlling the partial oxygen pressure between the decomposition oxygen pressures of NiO and Cu_2O; sintering temperature and holding time are vital for the relative density of the NiFe_2O_4-Cu cermets; the improvement of sintering temperature and prolonging of holding time are limited due to the low melting point and poor wetting characteristics of copper towards the NiFe_2O_4 phases, thus the relative density of NiFe_2O_4-Cu cermets obtained is less to assure its compositions uniformity and without metallic protrusion on the surface; the more the metal content of NiFe_2O_4-Cu cermet, the lower the maximum sintering temperature and the shorter the longest holding time, so its relative density is lower and its apparent porosity is higher. Besides decreasing the metal content, other metals with better wetting characteristics and higher melting point, such as nickel and cobalt, may be added to the NiFe_2O_4-Cu cermets to increase its sintering temperature, relative density and resistance.