Development of Ceramic Turbocharger Rotors for High-Temperature Use

A ceramic turbocharger rotor (CTR) for high-temperature use has been developed. The features of this rotor are the use of silicon nitride, which maintains high mechanical strength up to 1200°C, and a new joining technique between the ceramic rotor and its metal shaft. The CTR is expected to cope with stoichiometric mixture burning engines, which produce a higher exhaust gas temperature for fuel economy, and the impact resistance of the rotor against foreign object damage (FOD) has been markedly increased, over that of earlier rotors, resulting in higher reliability. This paper describes the development of ceramic turbocharger rotors for high-temperature use, focusing on the mechanical strength of silicon nitride and the joining of the ceramic rotor and its metal shaft.