Testing and Characterization of Near-Zero-Ablation Fibre-reinforced Ultra High Temperature Ceramics for Aerospace

This paper presents the results of extensive test campaigns carried out in the framework of the European C3HARME project, for the characterization of Ultra-High-Temperature Ceramic Composites for near-zero ablation Thermal Protection Systems (TPS) and near-zero erosion rocket nozzles. Tests were carried out in a supersonic arc-jet wind tunnel, where conditions typical of atmospheric re-entry were reproduced, and in different configurations in a lab-scale hybrid rocket engine. Materials having a ZrB2-SiC-based matrix and carbon fibre reinforcement showed an outstanding erosion resistance for both applications. In the arc-jet environment, a spontaneous temperature jump of 4-500 K was observed, which was attributed to a combination of increased catalytic activity and reduced thermal conductivity upon oxidation. In the high-pressure environment of the propulsion tests, long-fibre reinforcement demonstrated better mechanical resistance, which can be improved by proper tuning of the densification process. The small-scale results paved the way for large scale qualification tests on a complete TPS assembly and a medium-scale solid rocket nozzle.