What are Ultra-High Temperature Ceramics?

Ultra-high temperature ceramics (UHTCs) are a class of materials that have melting temperatures above 3000°C and that can potentially be used at temperatures above 1800°C.Among the compounds that are considered UHTCs are the borides, carbides, and nitrides of the early transition metals such as ZrB2, ZrC, HfB2, HfC, HfN, and TaC.

Where are UHTCs used?

Because of their thermal/chemical stability, strength at high temperature, and oxidation resistance, UHTCs can be used in extreme environments such as those associated with atmospheric re-entry, hypersonic flight, and rocket propulsion.Thus, the next generation of aerospace vehicles might use UHTCs as thermal protection materials, for wing leading edges, on control surfaces, and in propulsion systems.In addition, UHTCs are used as molten metal crucibles, high temperature electrodes, and refractories for steel making.

What type of UHTC research is performed at Missouri S&T?

Drs. Hilmas and Fahrenholtz have a variety of research programs focused on UHTCs.Agencies funding this research include the National Science Foundation, the Air Force Office of Scientific Research, the U.S. Army Space and Missile Defense Command, and the Air Force Research Laboratory. Individual projects focus on sintering of ZrB2, reaction-based processing, co-extrusion forming of fibrous monolithic ceramics, thermal shock resistance, phase equilibria, oxidation behavior, and high temperature mechanical properties.

Where can I go for more information?

Drs. Hilmas and Fahrenholtz from the Missouri S&T MSE department organized a workshop on research needs related to UHTCs.The workshop was jointly sponsored by the National Science Foundation and the Air Force Office of Scientific Research and it was held in January 2004 ( http://web.mst.edu/%7Euhtm/).A copy of the workshop report plus information on other researchers working on UHTCs can be found at the workshop website.In addition, a recent issue of the Journal of Materials Science (J. Mater. Sci., 39(19) October 1, 2004) was devoted to UHTC research.