Grain Growth Kinetics and Polytype Transformation of SiC During the Intermediate Stage of Induction Heating Sintering

Grain growth kinetics and polytype transformation play a critical role in determining the final microstructure and properties of SiC ceramics, particularly during the intermediate stage of sintering when the microstructure evolves most significantly. This study investigates the impact of pressureless induction heating on grain growth and polytype transformation during the intermediate sintering stage. By analyzing grain growth kinetics and its relationship with polytype transformation, the mechanisms governing these processes are examined to provide insights for controlling the microstructure and optimizing the properties of SiC ceramics. Rapid densification was observed during the temperature ramp, with the onset of the intermediate stage shifting to higher temperatures due to the high heating rate (200°C/min). Isothermal heating at 1975°C, 2000°C, and 2025°C resulted in significant grain growth and morphological changes within 10 min of heating. The results show that the grain‐growth behavior was attributed to polytype transformation, anisotropic grain growth, boron additives, and electromigration. The activation energy for grain growth was 222 ± 38 kJ/mol, which is lower than typical values for solid‐state processes. These findings provide valuable insights for optimizing the sintering of SiC ceramics in advanced applications.