| 摘要 |
Calcined alumina with a BET (Brunauer Emmett Teller) surface area of 10-20 m2/g and an average particle size of 0.5 microns or less, in which the principal crystalline phase is an alpha phase with no theta phase, is new. Independent claims are also included for the following: (1) production of calcined alumina by calcining a substance containing alumina and no other metal in an atmosphere with a steam partial pressure of 600 Pa or less; (2) fine alpha-alumina powder which has a purity of at least 99.99% and a BET surface area of at least 15 square m/g, is free of transitional alumina, and produces a fritted product with a relative density of at least 95% when calcined at 1250 degrees C and atmospheric pressure. |
