Hafnium diborides properties

M. Gasch, D. Ellerby, E. liby, S. Beckman, M. Gusman, and S. Johnson, Processing, Properties and Arc Jet Oxidation of Hafnium Diboride/Silicon Carbide Ultra High Temperature Ceramics, J. Mater. Sci., 39, 5925-5937 (2004). 

Ceramic borides, carbides and nitrides are characterized by high melting points, chemical inertness and relatively good oxidation resistance in extreme environments, such as conditions experienced during reentry. This family of ceramic materials has come to be known as Ultra High Temperature Ceramics (UHTCs). Some of the earliest work on UHTCs was conducted by the Air Force in the 1960 s and 1970 s. Since then, work has continued sporadically and has primarily been funded by NASA, the Navy and the Air Force. This article summarizes some of the early works, with a focus on hafnium diboride and zirconium diboride-based compositions. These works focused on identifying additives, such as SiC, to improve mechanical or thermal properties, and/or to improve oxidation resistance in extreme environments at temperatures greater than 2000°C. 

Gasch, M., Ellerby, D., Irby, E., Beckman, S., Gusman, M. and Johnson, S., Processing and Properties of Hafnium Diboride/Silicon Carbide Ultra High Temperature Ceramics, To be published in J. of Materials Science (2003). 

J.J. Melendez-Martfnez, A. Dominguez-Rodn guez, F. Monteverde, C. Melandri and G. De Portu Characterisation and high temperature mechanical properties of zirconium boride-based materials. Journal of the European Ceramic Society 22, 2543-2549 (2002). W.G. Fahrenholtz, G.E. Hilmas, I.G. Talmy and J.A. Zaykoski Refractory diborides of zirconium and hafnium. Journal of the American Ceramic Society 90, 1347-1364 (2007). 

---