Introduction The re entry from low Earth

As far as the ultra-high temperature advanced ceramic investigated in the present work is concerned, heat is transferred by different physical mechanisms. When exposed to supersonic high enthalpy oxidizing airflows, borides or carbides suffer only slight surface oxidization: as soon as a compact thermal oxide barrier is formed, this prevents further oxygen NLG-8189 into the native bulk material. One of the key differences between ablative materials and some advanced ceramics is the ability to manage and transfer heat in excess. Special ultra-refractory advanced ceramics have outstanding thermal conductivities compared to ablative materials [16] so that, in presence of relatively localized high heat fluxes, heat is mainly redistributed towards larger surface areas and rejected by energy radiation towards the ambient. In this sense, ultra-high temperature ceramics are therefore very promising materials to develop structures or components of hypersonic vehicles, e.g. wing leading edges, wing body junctions, engine inlets, nozzles, aerodynamic control surfaces, that experience also shock wave boundary layer interactions and therefore relatively high localized heat fluxes [17].