Fiber-Reinforced Metal Matrix Composites for High-Pressure Turbines, Phase II

For a selected vehicle and jet engine configuration, fuel consumption is to a significant degree dictated by the thermal efficiency of the engine. Achieving optimal thermal efficiency and minimizing fuel consumption require high temperature operation with minimum cooling of hot gas path components, including combustors, high-pressure turbine blades, and inlet nozzle (stator) vanes. In parallel, cost reduction and reliability enhancements can be achieved by minimizing system complexity, in part by eliminating or minimizing cooling and by eliminating the need for thermal barrier coatings. Currently, actively cooled superalloy turbine blades and vanes are constrained to a peak operating environment temperature of ~3000F. Successful implementation of cost-effective and reliable materials and processes with the capability for non-actively cooled operation to 3500F would result in dramatic gains in jet engine efficiency. Gains to date have in large part been achieved by evolutionary improvements in turbine blade alloys, thermal barriers, and cooling gas path designs. Anticipated gains from the use of ceramics and ceramic matrix composites (CMC) have been slow to accrue. This project is pursuing revolutionary improvements in materials and processing capabilities via the application of innovative fiber interfaces and melt infiltration processing and proven oxidation protection coatings to produce a durable and cost-effective carbon fiber-reinforced metal matrix composite (Cf/MMC) with mechanical properties and environmental resistance suited to cyclic and long-duration operation at turbine inlet temperatures to 3500F within the jet engine environment. In the Phase I base effort, conceptual design of representative composite hardware was performed; preliminary goals were identified for thermal, chemical, and mechanical properties of key turbine subcomponents; ultrahigh temperature metal matrix infiltration was successfully achieved; and test coupons were characterized. Subcomponent-scale fabrication demonstrators have been produced, and subcomponent test articles are being fabricated for testing in the Phase I option. Cumulatively, the Phase I results provide a promising demonstration of feasibility. In the Phase II base effort, a representative component demonstration will be performed followed by a cost-effective combustion environment component demonstration in the Phase II option, providing an early path to opportunities for future implementation of the technology. Project emphasis is on demonstration of turbine components, but the developed technology would also be applicable to applications for other hot section components including combustors.