Reaction processing for the development of ultra-high temperature ceramics

Research into ultra high temperature materials has increased in recent years due to the need for material systems that can withstand the temperatures associated with hypersonic flight applications. ZrB₂ and HfB₂ are among the candidates for these extreme conditions. These diborides have melting temperatures that exceed 3000⁰C, the potential for strength retention at elevated temperatures, and moderate oxidation resistance when compared to high temperature carbides. However, diborides have often been reported to exhibit low strength and significant strength degradation by 1500⁰C; therefore, limiting their use at high temperatures...This research focused on processing zirconium diboride (ZrB₂) ceramics that exhibit improved mechanical performance and reduced impurity content. Three processing methods have been used to produce dense ZrB₂ ceramics; conventional hot pressing, reactive hot pressing, and pressureless sintering --Abstract, page iv