Microstructure and properties of an HfB2-SiC composite for ultra high temperature applications

An ultra-high-temperature ceramic (UHTC) based on HfB2 was produced. The microstructure consisted of fine and regular diboride grains (2 μm average size), with SiC particulate distributed intergranularly, not rarely in clustered formation, and low levels of secondary phases were identified. The resulting thermo-mechanical properties proved interesting results for microhardness and fracture toughness. The microstructural alteration experienced within the explored temperature range renders the material unsuitable for service in extreme conditions of temperature and-pressure.