Property Screening and Evaluation of Ceramic Turbine Engine Materials

Abstract

An overview is presented of the pertinent thermal and mechanical properties of 26 structural silicon-base non-oxide ceramics that are candidates for advanced heat engine applications. Included are hot pressed, sintered and reaction sintered Si3N4 and SiC, and Silicon. Data are presented for flexure strength, elastic properties, strength degradation at long times due to subcritical crack growth, long term oxidation effects, creep resistance, fracture toughness, thermal expansion, thermal diffusivity, and thermal shock resistance. All materials are evaluated using the same test equipment so that valid comparisons can be made between materials. Emphasis is placed on predominant behavioral trends as related to material microstructure and purity, as determined by processing method. Structure-property relations are developed.