Thermo-chemical surface instabilities of SiC-ZrB2 ceramics in high enthalpy supersonic dissociated airflows

Conference Dates

September 17-20, 2017


Improved technologies and (re-usable) materials capable of operating under extreme conditions of temperature, heat flux and chemical attack are necessary to develop new generations of hypersonic flight vehicles and rocket engines. In this perspective, ultra-high temperature ceramics (UHTCs) are actively studied, pushed by the demand of materials/devices indispensable to operate in harsh environments typical of aerospace applications.

The state-of-the-art UHTCs are SiC-MeB2 composites (Me = Zr, Hf), with SiC in the form of particle, short fiber, whisker and polymer-derived ceramic. As oxidation of the SiC-containing MeB2 ceramics is inevitable, research efforts have been focused on improving their oxidation/ablation resistance adding different compounds to promote densification of the MeO2 scale and slow down the volatilization of the protective borosilicate glass.

The response of SiC-ZrB2 ceramics at typical conditions of thermal protection systems of a re-entry spacecraft was studied. Evidences of the limits below which SiC-containing UHTC might play regarding the sharp leading edge technology for hypersonic flights were tested by using an arc-jet ground facility. Incipient thermo-chemical surface instabilities in the form of jumps-of -radiance were observed and interpreted.

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