Tailoring the thermo-mechanical and ablation performance of carbon/carbon composites by fiber lamination hybridization

Carbon/carbon (C/C) composites suffer from limited ablation resistance due to oxidation and sublimation under extreme aerodynamic heating. While enhancing thermal conductivity can actively dissipate heat and reduce ablation rates, this often degrades thermomechanical properties. To resolve this trade-off, we propose a fiber lamination hybridization strategy that combines high thermal-conductivity mesophase pitch-based carbon fibers and high load-bearing polyacrylonitrile-based carbon fibers (CF_PAN). This approach tailors interlaminar thermal stress, promoting both interlaminar microcrack deflection and stress-induced graphitization degree in the matrix. Consequently, the hybrid composites exhibit simultaneously improved flexural strength (slightly higher than CF_PAN-reinforced laminated C/C composites) and in-plane thermal conductivity (up to 430 W m⁻¹ K⁻¹). The synergistic effects significantly enhance ablation resistance by not only reducing ablation-induced heat accumulation via active heat dissipation but also resistance to mechanical exfoliation. These advances enable the hybrid C/C composites to achieve superior comprehensive performance in complex aerodynamic environments.