Enhanced effect of AlF3 and its Co-regulatory effect with micron-scaled α-Al2O3 nuclei on alumina crystal growth in high-temperature calcination process

Industrial alumina was used as raw material in the high-temperature calcination process, and AlF 3 was introduced to promote mass transfer in the gas phase. The calcination environment, such as sealing, calcination temperature, and holding time, was analyzed to enhance the effect of AlF 3 to promote the crystal growth of alumina. Here, round-like flake α-Al 2 O 3 with an average particle size (D50) of about 18–38 μm were obtained at low dosages (0.1–0.4 wt%) of AlF 3 . The morphology and particle size of α-Al 2 O 3 were further adjusted by introducing different types of micron-scaled nuclei as template inducers. Round-like flake and spherical-like large single crystals α-Al 2 O 3 with an average particle size greater than 35 μm were obtained, respectively, with 65 wt% of 15 μm flake and 10 μm bulk α-Al 2 O 3 nuclei added. In addition, the regulation mechanism of AlF 3 and nuclei on alumina crystal growth was also discussed. Finally, a theoretical basis and technical support for preparing high-performance, low-cost, and high thermal conductivity alumina fillers was provided.