Low emissions, reliability, performance, economy and time: modern aeronautical propulsion systems have to satisfy increasingly challenging demands. Within this context, advanced materials are one of the key elements for engine improvements in the medium and long term. In fact, materials currently used present us with limitations related to more stringent operating conditions and, as a result, limit the implementation of new solutions.
Research is currently being carried out on two fronts to find ways to increase the turbine's efficiency. The first envisages an increase in the capacity to resist high temperatures. Temperatures have constantly increased over the years, but certain thresholds cannot be overcome due to the structural limits of the materials used to build the stator vanes and rotor blades. The second is weight reduction, which directly affects the engine's efficiency.
With regards to the gearbox, a crucial improvement is linked to the development of composite materials which can increase its structural resistance. This means improving the reliability and durability of components as well as reducing the gearbox's weight.
The materials currently used in aeronautical propulsion systems (primarily nickel and cobalt super-alloys in turbines and combustors, and aluminium and magnesium light alloys in gearboxes) have remained almost unchanged for the past twenty years. They have reached their limit in terms of technological development, chemical composition and in relation to the production process. The development of a new-generation alloy for use during the hottest stages of the turbine would bring about, on average, an increase in operating temperatures of approximately 30°C. However, this would only lead to very limited benefits.