Evaluation of Ceramic Rotor Strength by Cold and Hot Spin Tests

Abstract

Presently in Japan 100 kW ceramic gas turbines (CGT) for automobiles are under development, parts of which include a turbine rotor, scrolls, a combustor, and other parts made of ceramics and ceramic matrix composites. The rotor is designed to rotate at 110,000 rpm, equal to the maximum stress of 300 MPa, and to be exposed to temperatures up to 1350°C. Initially, the strength of ceramic rotors was evaluated by a burst test using a cold spin tester. The burst picture was observed and compared with the 4pt bending strength of the ceramic test specimens. Next, the strength of the rotors was tested by a hot spin test and the burst result of the rotor was evaluated. A high-speed camera was used to observe the rotor at the instant of burst under a high-temperature condition. Applying the result of the cold and hot spin tests, ceramics for turbine rotor were selected and the shape of the rotor was designed.