Patent ID: 7491379
Filing Date: 2009-02-17
Classification: B82Y,C01F,C01P

Abstract:
1. A method for producing nano-scale theta (θ)-phase alumina microparticles, comprising: providing an alumina mixed powder, the alumina mixed powder comprises θ-phase alumina powder and boehmite, wherein an amount of the θ-phase alumina powder in the alumina mixed powder is in a range from 30 percent to 95 percent by weight, and an alumina equivalent of the boehmite in the alumina mixed powder is in a range from 5 percent to 70 percent by weight; heating the alumina mixed powder to a first temperature and keeping it at the first temperature for a first period, so as to trigger a first phase transformation of the alumina mixed powder for forming α′-phase alumina microparticles; and quenching the α′-phase alumina microparticles to room temperature and heating it to a second temperature and keeping it at the second temperature for a second period, so as to trigger at least a second phase transformation of the α′-phase alumina microparticles for forming the nano-scale θ-phase alumina microparticles, wherein a particle size of the nano-scale θ-phase alumina microparticles is in a range from 30 nanometers (nm) to 150 nm, and a phase purity of the nano-scale θ-phase alumina microparticles is more than approximately 90 percent by weight.