Patent ID: 7341427

Claim:
A process of producing a nozzle segment of a gas turbine engine, the nozzle segment comprising at least one vane between and interconnecting a pair of platforms, the process comprising the steps of: casting the nozzle segment from a gamma prime-strengthened nickel-base superalloy having a nominal composition of, by weight, about 10 percent cobalt, about 8.9 percent chromium, about 2 percent molybdenum, about 7 percent tungsten, about 3.8 percent tantalum, about 4.8 percent aluminum, about 1.55 percent hafnium, about 0.11 percent carbon, about 2.5 percent titanium, about 0.1 percent niobium, about 0.05 percent zirconium, about 0.015 percent boron, balance nickel and optional minor alloying elements; depositing an environmental coating on a surface of the nozzle segment by thermal spraying a powder having a predominant particle size of less than 38 micrometers and having a nominal composition of, by weight, about 18 percent chromium, about 10 percent cobalt, about 6.5 percent aluminum, about 6 percent tantalum, about 2 percent rhenium, about 1 percent silicon, about 0.5 percent hafnium, about 0.3 percent yttrium, about 0.06 percent carbon, about 0.015 percent zirconium, about 0.015 percent boron, the balance nickel and incidental impurities; working the surface of the environmental coating to have a surface finish of less than 2.0 micrometers Ra; drilling cooling holes in the nozzle segment; and then applying an oxidation-resistant coating on the smoothed surface of the nozzle segment so as to maintain an outermost surface on the nozzle segment having surface finish of less than 2.0 micrometers Ra; wherein a ceramic thermal barrier coating is not deposited on the outermost surface defined by the environmental coating and the oxidation-resistant coating thereon.