| 摘要 |
PURPOSE:To improve the purity of the particles by preparing a seed grain capable of forming the same material as the desired ceramic fine powder by a reaction or capable of forming the same material by drying or calcining from a part of the raw alkoxide prior to agglomeration. CONSTITUTION:The N2 gas contg. a saturated alkoxide such as aluminum ethoxide leaving an alkoxide vaporizer 1 is partly sent to a nucleus generator 4 through a branch pipe and mixed therein with the N2 gas contg. saturated steam leaving a water vaporizer 2, and the mixture is hydrolyzed at about 150-180 deg.C to generate a seed grain as the nucleus. The gas contg. the seed grain is returned to the main pipe, the gaseous mixture is cooled in a first-stage condenser 5, supersaturated and subjected to nuclear condensation with the seed grain as the nucleus to form a droplet aerosol. The aerosol is then passed through a reheating part 7 and a second-stage condenser 6 to regulate the droplet diameter and sent to a main reactor 8. The aerosol is then mixed with excess steam sent from a main-reaction water vaporizer 3, the mixture is hydrolyzed to convert the discrete droplets into the spherical superfine particles of Al2O3, etc., having 0.05-5mum average diameter which are collected by the filter of a collector 9. |
