SiC Reinforced Ultra High Temperature Ceramic Materials for Structural Applications

The desire for higher performance engines and hypersonic vehicles requires that new materials be developed to meet the harsh environments that will be encountered in thermal protection systems and engine components.  One approach to higher thermal efficiencies in a gas turbine engine is to increase the turbine inlet temperature.  While hypersonic flight such as that encountered in scramjets or reusable space access vehicles will experience higher temperatures at the leading edges.  For a material to be successful in these environments it must be wear and erosion resistant and resistant to oxidation.  A class of materials known as ultra high temperature ceramics (UHTC) including carbides, nitrides, and borides of transition metals are prime candidates to fill these requirements. However, these materials suffer from inherent brittleness.  To increase the fracture toughness, fibers of other oxidation resistant materials like SiC can be added.  The strength, morphology, and dispersion of these fibers will play a crucial role in the ultimate strengthening of the UHTC composites. BENEFITS: Potential applications of SiC fiber reinforced UHTC materials are engine thrust chambers and structural insulators as well as thermal protection systems for leading edges of hypersonic flight vehicles.  Due to their good electrical conductivity, UHTCs with increased fracture toughness can also find uses as electrodes for spark machining.  UHTC materials may also find uses as catalyst supports.