Sintering kinetics and properties of NiFe ₂ O ₄ ‐based ceramics inert anodes doped with TiN nanoparticles

Abstract Sintering kinetics of NiFe ₂ O ₄ ‐based ceramics inert anodes for aluminum electrolysis doped 7 wt% TiN nanoparticles were conducted to investigate densification and grain growth behaviors. The linear shrinkage increased gradually with the increasing sintering temperature between 1000 and 1450°C, whereas the linear shrinkage rate exhibited a broad peak. The maximum linear shrinkage rate was obtained at 1189.4°C, and the highest densification rate was achieved at the relative density of 75.20%. Based on the pressureless sintering kinetics window, the sintering process was divided into the initial stage, the intermediate stage, and the final stage. The grain growth exponent reduced with increased sintering temperature, whereas the grain growth activation energy decreased by increasing sintering temperature and shortening dwelling time. The grain growth was mainly controlled by atomic diffusion. NiFe ₂ O ₄ ‐based ceramics possessed high‐temperature semiconductor essential characteristics. The electrical conductivity of NiFe ₂ O ₄ ‐based ceramics first increased and then decreased with increasing sintering temperature, reached their maximum value (960°C) of 33.45 S/cm under 1300°C, mainly attributed to the relatively dense and uniform microstructure. The thermal shock resistance of NiFe ₂ O ₄ ‐based ceramic was improved by a stronger grain boundary bonding strength and lower coefficient of linear thermal expansion.