COATING METHOD FOR SUPERFINE PARTICLE IN FLUIDIZED BED

摘要

PURPOSE:To produce ceramics, etc., which are homogeneous and have resistance to high temp. by destroying the aggregate of superfine particles with low high-frequency synthetic sound waves, dispersing and fluidizing the superfine particles and covering the surfaces of the fluidized superfine particles with prescribed coating by a thermochemical vapor deposition method. CONSTITUTION:In such a state that superfine particles 10 such as silicon nitride and silicon carbide are packed in the vessel 2 of a fluidized bed coating device 1, low high-frequency synthetic sound waves are generated from a speaker 4 and introduced into the vessel 2 via a waveguide 3. The resonant phenomena are generated in the aggregate of the superfine particles 10 with the low-frequency sound waves incorporated in the synthetic sound waves and the aggregate is destroyed and also the superfine particles are dispersed and fluidized with the high-frequency sound waves and the fluidized bed of the superfine particles 10 is formed. The coating substance is then carried from a thermochemical vapor deposition device 12 connected with the lower end part of the vessel 2 and mixed with hydrogen and carbon dioxide, etc., in the midway part of carriage, and when this mixture is blown to the fluidized bed via a perforated plate 8, the surfaces of the superfine particles 10 are covered with a homogeneous coating under a state heated at prescribed temp.