マイクロコンテナ粒子の流動層によるサブミクロンセラミックス微粉の合成

Abstract

The concept of a fluidized bed of microcontainer particles is proposed. Although conventional fluidized beds are not good at handling cohesive submicron particles, the use of microcontainer particles enables us to produce and process them in fluidized beds. To examine the proposed concept, the syntheses of nitrogen ceramic powders (Si3N4, TiN and AlN) through carbothermal reduction and nitridation were performed in a thin fixed bed and a fluidized bed at 1300-1550°C. In every case, submicron powders were successfully obtained. For Si3N4 synthesis, the SiO(g) loss from the fixed bed and the degrees of silica reduction and nitridation were determined as functions of time and temperature. Though the deposition of SiO vapor increased the stickiness of the bed, the bed was fluidized with no problems when the gas flow rate was sufficiently high for bubbling. The SiO vapor deposition in the freeboard was found to be controllable by adjusting particle size and the gas flow rate.