Ultra-High-Temperature Ceramic Matrix Composites for Hybrid Rocket Nozzles

This paper presents the results of the activities carried out in the framework of the Horizon 2020 project C3HARME aimed at characterizing a new class of Ultra-High-Temperature Ceramic Matrix Composites (UHTCMC) for application as hybrid rocket nozzle. The material is based on a ZrB2-SiC matrix reinforced with either short or long carbon fibres. An incremental approach has been adopted for the material characterization, in terms of test articles dimensions and geometrical complexity. In particular, a first screening of the most suitable materials candidates has been performed testing small button-like specimens exposed to the supersonic exhaust jet of a 200N-class hybrid rocket nozzle. Based on the results, flat disks to be placed inside the hybrid rocket combustion chamber were manufactured and tested to assess the capability of larger components to withstand the thermo-mechanical stresses expected inside the rocket. Finally, nozzle throat inserts and complete subscale nozzles were tested, comparing their behaviour to a classical graphite nozzle tested in the same operating conditions. Results showed that long fibers materials with optimised porosity level have strong mechanical properties and outstanding erosion resistance.