Patent ID: 8123872

Claim:
A process for carburizing a nickel-based superalloy substrate prior to depositing an aluminum-containing coating on a surface thereof so as to stabilize the substrate and inhibit formation of a secondary reaction zone during and following deposition of the coating, the process comprising the steps of: processing the surface of the substrate to be substantially free of oxides; heating the substrate in a non-oxidizing atmosphere to a carburization temperature; contacting the surface of the substrate with a carburization gas mixture comprising a diluted hydrocarbon gas while maintaining the substrate at the carburization temperature for a duration of less than 60 minutes so as to cause carbon atoms in the carburization gas to dissociate therefrom, transfer onto the surface of the substrate, diffuse into the substrate, and react with at least one refractory metal within the substrate to form carbides of the at least one refractory metal, the gas mixture comprising about 3 volume percent of the hydrocarbon gas and the balance essentially an inert gas and/or hydrogen, the hydrocarbon gas being at least one chosen from the group consisting of acetylene, ethylene, methane, and propane, the carbides being within a carburized region beneath the surface of the substrate; and then cooling the substrate in a non-oxidizing atmosphere to terminate the formation of the carbides in the substrate.