Reduction in α-transformation temperature of gibbsite and boehmite by powder mixing with seed

Addition of fine α-alumina powder as a seed by up to 50 wt% to a gibbsite (Al(OH)₃) powder sample enables it to reduce its α-transformation temperature from about 1360 to 1090°C. Intensive mixing of the sample with 50 wt% seed using a planetary mill lessens the α-transformation temperature further down to around 910°C. A similar trend can be seen in the boehmite sample. The intensive mixing (grinding) of these samples by the planetary mill is accompanied with their size reduction, dispersing fine particles that play a significant role to reduce the α-transformation temperature in the calcination stage.