Effect of hafnium carbide content on the ablative performance of carbon/carbon composites as rocket throats

Hafnium carbide (HfC) modified carbon/carbon (HfC-C/C) composites were prepared by impregnating carbon felts with a saturated HfOCl₂·8H₂O ethanol solution and heat treating at 600°C to form HfO₂/C composites that were then densified with pyrocarbon by chemical vapor infiltration and graphitized at 2100°C to convert HfO₂ into HfC. The HfC-C/C composites as rocket throats were ablated at 7 MPa and around 3200°C for 3 s by an experimental solid rocket motor. Results showed that the HfC-C/C composites with HfC contents more than 5.7 mass% had a stable period with a constant ablation rate and the duration of this period increased with HfC content. The overall ablation rate was decreased by 25.2 and 49.6% for the composites having 5.7 and 8.7 mass% HfC respectively as compared with the composite with 2.5 mass% HfC.