Abstract: The present invention discloses a thermal spray apparatus with improved thermal efficiency and wear resistance in both the nozzle and barrel combustion chamber. Specifically, disclosed herein is a thermal spray apparatus for spraying substrate coatings, comprising a high velocity oxygen fuel (HVOF) gun wherein said gun includes a combustion chamber generating heated flow therefrom and a nozzle downstream from said chamber. The nozzle and/or chamber contain a first layer of material heated by the flow, and a second layer of material which contacts the first layer when said first layer is heated. The first layer has a thermal conductivity that is lower than said second layer and preferably a lower thermal expansion coefficient. In use, the contact of the first heated layer of material with the second layer operates to remove heat from the first layer therein providing automatic/self-regulating temperature control of the HVOF apparatus.

Abstract: A metal spray gun of the arc spray type has a nozzle-positioner member of electrically insulating material that is disposed between a gas inlet and an arc zone. A primary stream of gas is flowed through a through passage in the nozzle-positioner member, and seat surfaces in the through passage receive tips of individual electrically conductive contact tube assemblies that are biased outwardly away from one another. The nozzle-positioner member aligns the contact tube assemblies and configures the gas stream such that each metal wire is immediately enveloped in gas flow as it emerges from its contact tube and remains in that enveloping gas flow throughout the region between the contact tube tip and the arc zone. The spray gun produces quality metal spray coatings with lower gas pressures and has lower noise levels.