Materials for Electric Machines Suited for High-Temperature Applications: a Survey

The push towards the concept of More Electric Aircraft (MEA) and More Electric Engine (MEE) has introduced new challenges in the electric machines design. In fact, the eventual integration of the electric starter/generator directly into the engine envelope would allow to remove any accessory gearbox, leading to a potential improvement of the overall reliability and efficiency of the system with a consequent reduction of the environmental impact. However, the integration of an electric machine within the turbo-fan engine requires a completely new design approach, since conventional materials cannot withstand the high temperatures up to 500 degrees C usually found in such harsh environment. In this paper a survey on the main materials that can be used for electrical machines operating at high temperature (hot spot 500 degrees C) is presented, illustrating their key characteristics and the main manufacturing challenges related to the operation in a such hostile environment.