Development of Silicon Nitride Turbine Rotors

This paper describes fabrication of silicon nitride radial turbine wheels 90 mm in diameter. The wheels were hot spin tested without failure at turbine tip speeds up to 600 m/s. The reliability of shrink fit of metal shaft and ceramic wheel was demonstrated in a turbocharger test. Results of the hot spin test are discussed in relation to the nature of defects and compared with the analytic prediction using Weibull statistics and finite element analysis.