Process and apparatus for coating particles with fine powder

A process of coating ceramic particles with fine metallic powder which comprises:

• a. providing a mixture comprising ceramic cores selected from the group consisting of Al.sub.2 O.sub.3 and SiC particles, and a binder selected from the group consisting of polyethylene glycol and paraffin, said binder being present in an amount of about 0.5 to about 5 weight percent of said ceramic cores, said binder being capable of reaching viscous state below about 80.degree. C.,
• b. tumbling said mixture in a rotating cylindrical container which is tilted with respect to horizontal axis, while heating said mixture to a temperature up to about 80.degree. C. to enable said binder to reach said viscous state, and allowing said particles to be substantially covered with said binder,
• c. cooling the mixture of binder covered particles substantially to room temperature and thereafter breaking up particles that may have agglomerated during said tumbling and heating by tumbling same with ball means, to give individual particles covered with said binder,
• d. adding a fine metal powder selected from the group consisting al Al, Cr, Fe, Ni, Co, Mo and W to said individual particles covered with binder and tumbling and heating again in said rotating cylindrical container at a temperature up to about 80.degree. C. to said viscous state under conditions effective to provide a coating of said fine metallic powder on said particles.

A process for coating particles with fine powder which comprises:

• a. providing a mixture comprising said particles and a binder which is capable of slowly melting to viscous state,
• b. tumbling said mixture while slowly heating same to enable said binder to reach said viscous state while allowing said particles to be substantially covered with said binder,
• c. cooling the mixture substantially to room temperature and thereafter breaking up particles that may have agglomerated during said tumbling and heating, to give individual particles covered with said binder,
• d. adding said fine powder to said individual particles covered with said binder and tumbling and heating again to said viscous state under conditions effective to provide a coating of said fine powder on said particles, and
• e. heating said coated particles to remove said binder leaving said particles exclusively coated with said fine powder.