UHTCs: Ultra-High Temperature Ceramic Materials for Extreme Environment Applications

摘要

Ultra-High Temperature Ceramics are a family of compounds that display a unique set of properties, including extremely high melting temperatures (> 3000 deg C), high hardness, and good chemical stability and strength at high temperatures. Structural materials for use in high-temperature oxidizing environments are presently limited mostly to SiC, Si3N4, oxide ceramics, and composites of these materials. The maximum-use temperatures of silicon-based ceramics are limited to approximately 1700 deg C due to the onset of active oxidation (lower temperatures in water vapor environments. The development of structural materials for use in oxidizing and rapid heating environments at temperatures above 1700 degC is therefore of great engineering importance. UHTC materials are typically considered to be the carbides, nitrides, and borides of the transition metals, but the Group IV-V compounds (Ti, Zr, Hf, Ta) are generally considered to be the main focus of research due to the superior melting temperatures and formation of stable high-melting temperature oxides. The combination of properties make these -materials potential candidates for a variety of high-temperature structural applications, including engines, hypersonic vehicles, plasma arc electrodes, cutting tools, furnace elements, and high temperature shielding.