Mechanical and Ablative Properties of TiC-B 4 C Modified Carbon Fiber/Boron Phenolic Resin Composites in High-Temperature Environments

Carbon fiber/phenolic resin composites (CF/Ph) are often used on the surface of hypersonic vehicles as thermal protection materials. In this paper, the composite materials were prepared by a compression molding process with carbon fiber and boron phenolic resin modified by TiC and B4C. The high-temperature flexural strength and anti-ablation behavior of the composites (TB) were studied. The results showed that the residual weight yield at 1500 °C of TB-10 (B4C content of 10 phr) increased by 39.22% compared to that with no B4C (TB-0). The flexural strength of TB-10 was increased by 19.51% and 19.69% at 1400 °C and 1600 °C, respectively, with respect to TB-0 at the same temperatures. The linear ablation rate and mass ablation rate of TB-10 were reduced by 24.32% and 5.58%, respectively, compared with TB-0. By exploring the anti-ablative mechanisms, it was revealed that PyC, liquid B2O3 and TiO2, all of which were formed at high temperatures, tended to fill the inner cracks of the composite and, therefore, prevent the oxide to further diffuse in. Along with the outer ceramic layer, the three components above play a synergistic effect to improve the ablative property.