Dense oxide coatings by thermal spraying.

摘要

A thermal spray gun (10) includes a nozzle member with an axial conduit (34) that conveys a powder stream of heat fusible oxide ceramic in a carrier gas. The conduit (34) terminates at the nozzle face in a plurality of radially divergent orifices (65). A gas cap (14) extends from the nozzle member and defines a combustion chamber (82). An annular flow of a combustible mixture is injected from the nozzle member coaxially into the combustion chamber (82). Air is injected adjacently to the gas cap wall so that a spray stream containing the ceramic is propelled through the open end, preferably supersonic. An aluminum oxide coating sprayed thereby should comprise substantial alpha phase and have good dielectric breakdown strength.