Abstract: A method and apparatus are provided for operating a small diameter thermal spray gun to thermal spray a coating onto a substrate. A liquid fuel and regeneratively heated air are swirled together within a mixing chamber, passed through a restricter plate orifice, and then passed into the combustion chamber to atomize the liquid fuel and mix the liquid fuel with the regeneratively heated air. The liquid fuel is then burned within a combustion chamber of a small diameter thermal spray gun to generate a high energy flow stream, into which a coating material is injected. The combustion chamber includes an inner sleeve with cooling ports which pass cooling air laterally therethrough. A flow nozzle directs the high energy flow stream towards the substrate. The flow nozzle transfers a heat flow from a first portion of the high energy flow stream to a second portion of the high energy flow stream, and provides a thermal barrier to retain heat within the high energy flow stream.

Abstract: A method and apparatus are provided for operating a small diameter thermal spray gun to thermal spray a coating onto a substrate. A fuel is burned within a combustion chamber of a small diameter thermal spray gun to generate a high energy flow stream, into which a coating material is injected. The combustion chamber includes an inner sleeve with cooling ports which pass cooling air laterally therethrough. A flow nozzle directs the high energy flow stream towards the substrate. The flow nozzle transfers a heat flow from a first portion of the high energy flow stream to a second portion of the high energy flow stream, and provides a thermal barrier to retain heat within the high energy flow stream. The small diameter thermal spray gun may be tuned for operating with a wide variety of coating materials by replacing the combustion chamber inner sleeve and the flow nozzle thermal transfer member with alternative members.

Abstract: A method and apparatus for thermal spraying a coating onto a substrate is provided wherein a coating material is transported within a high energy flow stream. A high energy flow stream, which includes the coating material, is generated within the thermal spray gun. A flow nozzle having a barrel directs the high energy flow stream towards the substrate. The flow nozzle includes a thermal transfer member for absorbing a heat flow from a first portion of the high energy flow stream, and transferring the heat flow back to a second portion of the high energy flow stream. Additionally, the thermal member provides a thermal barrier for retaining heat within the high energy flow stream by absorbing and retaining sufficient heat within the thermal flow nozzle so that the temperature gradient between the high energy flow stream and the flow nozzle is reduced, which reduces the amount of heat transferred therebetween.