The need for materials that can withstand high temperatures has led to the development of metal-matrix composites (MMCs) and ceramic-matrix composites (CMCs). MMCs offer strength and ductility, but are heavy and complex to process. CMCs, on the other hand, have superior heat resistance and low abrasive and corrosive properties, but are brittle and require sintering, a process that renders a combination of materials into a coherent mass by heating to high temperatures. CMCs are used in aircraft engines, allowing for higher operating temperatures and reduced fuel consumption. Another type of composite, carbon-carbon composites, consists of semicrystalline carbon fibers embedded in a matrix of amorphous carbon and are used in nose cones of reentry vehicles.
Research is also focused on developing materials with specific properties for use in space, such as materials with near-zero coefficient of thermal expansion and high-toughness materials. Additionally, “smart” materials are being developed, which have built-in sensors and actuators that can react to their external environment by bringing on a desired response. These materials could be used to suppress vibration and improve safety in aircraft interiors.