Process and apparatus for coating particles with fine powder

摘要

There is disclosed a process for coating particles, such as ceramic, metallic and organic cores, with fine powder, such as ceramic, metal, organic or carbon powder. The process comprises providing a mixture comprising the particles and a binder which is capable of slowly melting to viscous state. Then the mixture is tumbled while slowly heating it to enable the binder to reach the viscous state while allowing the particles to be substantially covered with the binder. The next step includes cooling the mixture to about room temperature and thereafter breaking up the particles that may have agglomerated during the tumbling and heating to give individual particles covered with the binder. As a final step, the fine powder is added to the individual binder covered particles and the mixture is tumbled and heated again to the viscous state under conditions effective to provide a coating of the fine powder on the particles. Additional heating may be carried out to remove the binder and leave particles exclusively coated with the fine powder. The apparatus includes a rotating cylinder, heating and cooling means. The resulting product has a more uniform microstructure and higher bonding strength than a product resulting from a conventional mixing of ingredients.