Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications IV

Memo

Ultra-High Temperature Ceramics are a family of compounds that display a unique set of properties, including extremely high melting temperatures (>3000°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 is limited to ~1600°C due to the onset of active oxidation (lower temperatures in water vapour environments), whilst oxides have exhibited high creep rates at higher temperatures. The development of structural materials for use in oxidizing and rapid heating environments at temperatures above 1600°C 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 compounds (Ti, Zr, Hf) plus TaC are generally considered to be the main focus of research due to the superior melting temperatures and stable high-melting temperature oxide that forms in situ. The combination of properties make these materials potential candidates for a variety of high-temperature structural applications, including engines, hypersonic vehicles, plasma arc electrodes, advanced nuclear fuels, fusion first walls and divertors, cutting tools, furnace elements and high temperature shielding.



A major focus of recent work is to combine the properties of the UHTC compounds with the concepts behind the design and manufacture of ceramic matrix composites, to form a new class of materials known as UHTCMCs. When this development is combined with the ongoing work on MAX phases[1], materials that share many processing characteristics with the UHTC phases, it makes sense to bring researchers working in this area together. In addition, potential applications for UHTCs and MAX phases outside of aerospace are now being researched, e.g. in nuclear, defence and other structural applications. The purpose of this meeting is to thus bring together interested parties from academia, government and industry in a single forum that allows the bench researchers to interact with designers and engineers to discuss state-of-the-art research and development efforts, what the results mean in a broader context and how to move the technology forward toward near-term and longer term use.







[1] Materials that share both ceramic (high temperature capability, high elastic modulus) and metallic properties (machineability).