Structural stability of UHTCs in extreme environments

Hypersonic flights, re-entry vehicles, and propulsion applications all require new materials that can perform in oxidizing or corrosive atmospheres at temperatures in excess of 2000°C and sometimes over the course of a long working life. The Ultra High Temperature Ceramics (UHTCs) are good candidates to accomplish these requirements. Within this family, borides and carbides based composites are the most attractive. The UK research programme of UHTCs mainly spins around the development and testing of UHTCs and UHTC infiltrated Cf/C composite systems. This work mainly concerns about the high temperature behaviour of UHTCs including oxidation. UHTCs were densified mainly by spark plasma sintering technique and the oxidation studies were particularly carried out for both borides and carbides based UHT Composites developed in the UK using furnace and collimated laser beam. The oxidation kinetics of different UHTCs at high temperatures and the microstructural stability of the UHTCs (oxidised layers) are investigated. The results from these experiments are analysed using computation methods using ANSYS and solid works for the viability of using UHTCs for aerospace applications in extreme environments.