关键词: 矾土均化料, 热处理温度, 物相组成, 显微结构

Abstract: Bauxite-based homogenized grogs with 85 mass% Al₂O₃ were prepared through wet co-grinding homogenization and high-temperature heat treatment,and utilizing D-K type bauxite as the raw material.The evolution of the phase composition,microstructure,and properties of the bauxite-based homogenized grogs during the heating process (800-1 630 ℃) was systematically studied using thermodynamic software FactSage,XRD and SEM.The results show that the main crystal phases of the sample are corundum and mullite;as the heat treatment temperature increases,the corundum content decreases gradually while the mullite content increases gradually;(2)within 800-1 550 ℃,as the heat treatment temperature increases,the apparent porosity and water absorption of the sample rapidly decrease,while the linear shrinkage,bulk density,and the cold compressive strength significantly increase;within 1 550-1 630 ℃,the properties of the sample tend to stabilize,with the apparent porosity less than 3.4%,the water absorption rate less than 1.00%,the linear shrinkage rate of about 16%,the bulk density higher than 3.27 g·cm^-3,and the cold compressive strength higher than 460 MPa;the sample is basically densified;(3)after heat treatment at temperatures of 1 400 ℃ or below,the corundum crystals in the sample are small and porous,while the mullite crystals are microcrystalline and not fully developed;the pores are mainly open or through;after the heat treatment at 1 600 ℃ or above,the sample exhibits a typical network structure of alternating corundum and mullite phases;the glass phases are few and isolatedly distributed in the network structure of the corundum grains or mullite grains;the pores are mainly closed;(4)thermodynamic calculations show that the liquid phase is generated in the samples at 1 150 ℃,and the amount of the liquid phase gradually increases with the increasing temperature;while the viscosity of the hot liquid phase significantly decreases.

Key words: bauxite-based homogenized grogs, heat treatment temperature, phase composition, microstructure