Carbon/Carbon Components for Advanced Gas Turbine Engines

A preliminary assessment of carbon/carbon fiber/matrix composites for extreme temperature limited life service in small gas turbine engines has been completed. Spin tests of available disks were conducted, along with structural design micromechanical analyses of tested specimens and conceptual variants. Many specific strength values at ambient temperatures were found higher than those of presently used metals. Since these values increase as temperatures are elevated, a significant advantage is provided over contemporary and advanced turbine wheel materials. A major advantage of C/C composite over monolithic ceramic is a relative absence of defect sensitivity, brittleness, or rapid fracture progression. Experiments and studies were conducted to provide carbon/carbon bodies with state-of-the-art oxidation and erosion protection. Silicon carbide coated specimens show required promising static oxidation resistance for target engine mission life. Simulated dynamic end use tests have yet to be completed. It is recommended that further programs on carbon/carbon composite turbine components be conducted immediately to address coating refinement, component design, development of appropriate fiber architecture, and characterization of those architectures which result in acceptable service properties on tested components.