Abstract: A thermal spray combustion gun including a burner assembly, a combustion chamber assembly, a middle gun body, and a spring. The spring is structured and arranged to provide a spring force that maintains a first metal-to-metal seal between the burner assembly and the combustion chamber assembly, and maintains a second metal-to-metal seal between the combustion chamber assembly and the middle gun body.

Abstract: A gas cap for a thermal spray gun has a passage therethrough including an entrance channel, an exit channel, and an intermediate channel connecting between the entrance and exit channels. The entrance channel is cylindrical on an entrance axis, and the exit channel is convergingly conical on an exit axis oriented at 45.degree. to the entrance axis. The intermediate channel is symmetrical to the plane of the entrance and exit axes and has a near portion and a far portion. The near portion is semicylindrical about the entrance axis, and the far portion is semicylindrical about a far axis segment lying in the plane. That segment is offset from the entrance axis away from the exit end of the gas cap, and is oriented at 14.degree. to the entrance axis, the three axes intersecting at a common point.

Abstract: The front face of the nozzle of a plasma spray device has a shallow annular recession therein. The recession is bounded inwardly by an extended portion of the nozzle, outwardly by a ring member and rearwardly by an inner surface. The ring member has therein a plurality of arcuately equally spaced holes directed radially inward toward the inner face, the holes communicating with a source of air. Powder is injected radially into the plasma stream external to the nozzle member proximate the outlet end. The air flow from the holes and entrainment of surrounding atmosphere by the plasma stream drive a toroidal vortex anchored in the recession, the vortex effecting a wiping flow on the nozzle face such as to inhibit powder from depositing on the nozzle face.

Abstract: A method of and apparatus for producing a dense and tenacious coating with a thermal spray gun including a nozzle member and a gas cap. The gas cap extends from the nozzle and has an inwardly facing cylindrical wall defining a combustion chamber with an open end and an opposite end bounded by the nozzle. An annular flow of a combustible mixture is injected at a pressure of at least two bar above atmospheric pressure from the nozzle coaxially into the combustion chamber. An annular outer flow of pressurized air is injected from the nozzle adjacent to the cylindrical wall. Heat fusible powder entrained in a carrier gas is fed axially from the nozzle into the combustion chamber. An annular inner flow of pressurized air is injected from the nozzle into the combustion chamber coaxially between the combustible mixture and the powder-carrier gas. Upon combusting the annular mixture a supersonic spray stream containing the powder is propelled through the open end to produce a coating.

Abstract: A plasma gun for spraying in a recessed region comprises a cathode member and a tubular anode arranged with the cathode member to generate a plasma stream. An elongated tubular extension including a tubular wall with an axial plasma duct therein extends forwardly from the anode. A transverse plasma duct causes the plasma stream to exit transversely from the tubular extension. Channeling for fluid coolant is in the tubular wall and extends substantially the length of the axial plasma duct. A first external pipe connected to the tubular extension forwardly of the transverse duct directs fluid coolant to the channeling. A powder injector injects spray powder rearwardly into the exiting plasma stream. A second external pipe from a powder source is connected to the powder injector.