Ablation behavior of ZrSi2-B4C-modified carbon fiber/boron phenolic resin ceramizable composites at different heat fluxes

Carbon fiber/phenolic resin (CF/Ph) composites are widely used as outer surface thermal protection materials in hypersonic vehicles because of their excellent ablation resistance. As the flight speed of the vehicle increases, the problem of CF being prone to oxidation in high-temperature aerobic environments becomes more severe, hindering the adaptation of CF/Ph to more extreme service environments. In this study, ZrSi 2 -B 4 C was introduced into carbon fibre/boron phenolic resin (CF/BPR) to improve its ablation resistance. At 2.4 MW/m 2 , the linear ablation rate (LAR) and mass ablation rate (MAR) of the composites were as low as −0.032 mm/s and 0.0186 g/s, respectively. At 3.6 MW/m 2 , the LAR and MAR were as low as −0.005 mm/s and 0.0273 g/s, respectively. These findings indicate that the ceramizable composites exhibit excellent ablation resistance under both low and high heat flux conditions. The ablation mechanism of the composites was revealed. The in situ ceramization of ZrSi 2 and B 4 C formed a Zr-Si-B-C-O ceramic layer, which hindered the thermal oxidation and aerodynamic erosion of CF and PyC.