Method for producing plate-like alumina powder and plate-like alumina powder

摘要

96 parts by mass of γ-alumina powder, 4 parts by mass of AlF 3 powder, and 0.17 parts by mass of α-alumina powder as a seed crystal were mixed in a pot mill. When the purity of each used raw material was evaluated, the mass ratio of each element other than Al, O, F, H, C, and S was 10 ppm or less. 300 g of the obtained mixed powder was put in a sheath made of high-purity alumina having a purity of 99.9% by mass, covered with a lid made of high-purity alumina having a purity of 99.9% by mass, 900 ° C., 3 ° C. in air flow in an electric furnace. A plate-like alumina powder was obtained by heat treatment for a time. The value obtained by dividing the AlF3 mass by the sheath volume (AlF3 mass / container volume) was 0.016 g / cm3. The obtained plate-like alumina particles were α-alumina particles having an aspect ratio of 11.5.