Patent attributes
A turbine airfoil, or a substrate exposed to a high temperature environment, having a plurality of individual cooling circuits in the airfoil wall, each individual cooling circuit having a first metering hole connecting the cooling circuit to a cooling air supply, a first diffusion cavity, a second metering hole, and a plurality of fine film cooling holes connected between the second diffusion cavity and the surface of a high temperature resistant coating. The coating is a refractory coating to provide higher heat resistance than a ceramic based thermal barrier coating. A process of forming the individual cooling circuits is also disclosed, where a ceramic core representing the above described cooling passages is secured in a “fish bowl” shaped cavity in the substrate wall, the refractory coating is applied to just under the core fingers, and the ceramic core is leached out to leave behind the cooling circuit. The cooling circuit thus formed includes a first metering hole, a first diffusion cavity, a second metering hole, a second diffusion cavity, and a plurality of micro film cooling holes to provide transpiration cooling to the coating surface.
