Impact of sintering thermal history on MgO‐doped alumina: Reduction of grain growth constant through high heating rates
Milad Kermani, Jinghua Wu, Ze-Xiao Liu, Fei Zuo, Hua‐Tay Lin, Chunfeng Hu, Salvatore Grasso
Abstract
Abstract This work examines the impact of sintering thermal history on kinetics of grain growth for 1264 ppm (0.1 wt%) MgO‐doped alumina. Results suggest that sintering with a high heating rate in the order of ∼10 3 °C min −1 retards grain growth rate. By contrast, a slow heating rate of 5°C min −1 resulted in an increase in grain growth constant by a factor of ∼4. The segregation of Mg to grain boundaries, favored by short sintering duration, is considered to be one of the possible factors contributing to the retarded grain growth rate for the rapidly heated compacts. Furthermore, it is proposed that the simultaneous combination of retarded grain boundary migration rate and limited surface‐diffusion‐driven grain coarsening, promoted by rapid heating, enables pressure‐less fabrication of translucent alumina without a need for vacuum or hydrogen atmosphere. In fact, it is demonstrated that weakly translucent alumina can be produced at relatively low temperatures of 1475–1550°C by sintering with a high heating rate (herein, ∼10 3 °C min −1 ) in ambient atmosphere.