ZrB2–SiC Sharp Leading Edges in High Enthalpy Supersonic Flows

Abstract

Aero‐thermodynamic tests have been carried out in an arc‐jet supersonic plasma wind tunnel using a very sharp wedge made of ultra‐high temperature ceramic (UHTC) in the ZrB2–SiC system. The comparison with a lower thermal conductivity ceramic material (Si3N4–MoSi2) with the same sharp shape, pointed out at the performance advantages of the UHTC material. When subjected to heat fluxes in the order of 7 MW/m2, the surface temperature of the UHTC wedge increased up to 2450°C near the leading edge. The present study demonstrated that the high thermally conductive UHTC survived such extreme conditions by re‐distributing heat over colder regions downstream of the sharp tip. As a consequence, radiative equilibrium temperatures in the range 1400°C–1650°C were established over 85% of the exposed surface. On the other hand, the less thermally conductive Si3N4–MoSi2 material failed to withstand the same heat flux and underwent partial melting with significant mass loss. The post‐test microstructural observations of the UHTC wedge proved to be a fundamental source of information which was input into a Computational Fluid Dynamics (CFD) code and by a thermal simulation software to simulate the experimental tests and correlate the in situ observations of the material evolution during testing.