Spray nozzle assembly for gas dynamic cold spray and method of coating a substrate with a high temperature coating

A method for gas dynamic cold spraying a substrate with a high temperature coating comprising the steps of

• (a) providing a substrate
• (b) providing a powder which has a melting temperature of more than about of 700° C. which powder is to be applied to the substrate;
• (c) providing an apparatus having a housing with an inlet for a gas and a mixing cavity disposed within the housing for mixing the powder and the gas in communication with the inlets, the cavity having an exit therefrom;
• (d) providing a nozzle assembly including a nozzle holder having a bore centrally disposed therethrough and further including a cooling jacket, and a non-metallic nozzle having an exterior surface, a central longitudinal axis and a centrally disposed bore therethrough,
• (i) said nozzle bore having a converging shape extending partway therethrough from an inlet of the nozzle bore and a diverging shape extending toward an outlet end of the nozzle bore,
• (ii) the nozzle bore inlet in communication with said mixing cavity exit,
• (iii) the nozzle positioned within said bore of said nozzle holder at a position spaced longitudinally away from the nozzle bore inlet, and the cooling jacket providing a cooling media in thermal communication with at least a portion of the nozzle exterior surface adjacent the nozzle bore inlet.