Gas turbine nozzle segment and process therefor

摘要

A gas turbine engine nozzle segment (10) and process for producing such a nozzle segment (10) to exhibit improved durability and aerodynamic performance. The process produces a nozzle segment (10) having at least one vane (12) between and interconnecting a pair of platforms (14,16). The nozzle segment (10) is cast from a gamma prime-strengthened nickel-base superalloy, on whose surface is thermal sprayed an environmental coating (22) formed of a MCrAlX-type coating material. The surface of the environmental coating (22) is then worked to cause the coating (22) to have a surface finish of less than 2.0 micrometers Ra. Cooling holes (26) are then drilled in the nozzle segment (10), after which an oxidation-resistant coating (24) is applied on the smoothed surface of the nozzle segment (10) so as to maintain an outermost surface on the nozzle segment (10) having surface finish of less than 2.0 micrometers Ra.