Recent achievements on arc-jet testing of UHTC with a sharp profile

The contribution is addressed to offer an overview of recent achievements on some borides-based composites that are conventionally classified as ultra-high temperature ceramics (UHTCs) for their extremely high melting points. UHTCs are currently the most studied key enabling technology for thermal protection structures (TPS) like wing leading edges, surface control components to be applied in the next generation of space vehicles flying at hypersonic speed or/and re-entering the Earth's atmosphere. They are characterized by sharp profiles to increase performances and maneuvrability. Sharp wedges and blunt(er) hemispheric test articles were fabricated in the ZrB2 base system, using SiC particulate or SiC short fibers as second phase. Microstrcture evolutions and fundamental thermo-mechanical characteristics were determined. The dynamic response to oxidation of such UHTCs was studied under aero-thermal heating using high enthalpy supersonic flows in arc-jet plasma wind tunnel. Microstructural changes were analyzed and correlated to test conditions through Computational Fluid Dynamics (CFD) simulations