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The bending strength of specimens of various sizes, some of which were cut from a turbine wheel, was compared with predictions using Weibull statistical theory. The stress distribution of a ceramic turbine wheel in spin testing was determined with finite elements and the results were used to analyze a wheel that was spun until it burst. The cause of the burst of the ceramic radial turbine wheel at elevated temperature is discussed and based on the tensile rupture data. A design methodology using the Larson-Miller parameter was found to be applicable to the ceramic components at elevated temperatures.

Development of ceramic components for a 300kW recuperative single-shaft ceramic gas turbine, a program in the Moonlight Projects, is being conducted by the New Energy and Industrial Organization (NEDO). Along with its program, NGK has made technical efforts in cooperation with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI) since 1988. In this paper, the strength of the NGK silicon nitride turbine blade is discussed. Bending strength was checked with specimens cut from the turbine blades, and specifically, cold spin tests were conducted with ceramic turbine blades having three configurations. The silicon nitride was found promising for ceramic gas turbine applications, however, there are some issues to be solved prior to prototype engine tests.