Functional coarse grained alumina-niobium composites for electrical heating applications

Within the framework of the FOR 3010 research activities, a new generation of refractory (composite) materials is developed with the aim to replace conventional refractory ceramics and metals. The present work focuses on the development of electrically heatable functional components based on a pre-synthesized, electrically conductive niobium–alumina refractory material. A heat shield was selected as a demonstrator component for the gas turbine applications; it was manufactured using slurry-based casting technology in core-shell design. Pure alumina was used as shell material, providing chemical protection for the conductive niobium-alumina core material. The fabricated components exhibited an excellent surface quality and a sufficient modulus of rupture after sintering. Electrical heating experiments showed that the successful developed composite heat shield can be heated to a surface temperature of 110°C within 70 min.