Advanced Lightweight Silicide and Nitride Based Materials for Turbo-Engine Applications.

Refractory metal silicides and nitride-based ceramics combine two properties that may lead to substantial reductions in aircraft fuel consumption : compared to the most advanced nickel-based superalloys presently used in aeronautical turbines, they can withstand higher temperatures and may have lower densities. Niobium silicide-based alloys and silicon nitride / molybdenum disilicide composites are currently being developed for turbine hot section components for both aircraft engines and land-based turbines. This paper presents the processing techniques, the microstructural features and the mechanical and physical properties at low and high temperatures as well as the oxidation behaviour of these materials. Prospects in composition optimisation, manufacturing processes and control of the microstructure for further improvements are discussed.