Ablation and heat insulation performances of nose-shaped ZrC-C composites with gradient pore structure

Nose-shaped ZrC-C composites with gradient pore structure (ZrC-C_GS) were successfully prepared by isothermal chemical vapor infiltration using ZrC skeleton as preform. Pyrolytic carbon with medium texture was deposited around ZrC skeleton. From the top to back, the porosity of the ZrC-C_GS composites increased gradually from 0% to 62.9%. Compared with the ZrC-C composites with dense structure (ZrC-C_DS), the mass ablation rate of the ZrC-C_GS composites decreased by 15.3% and the heat resistance capacity increased by 45.6%, and their coefficients of thermal expansion decreased obviously in the temperature range of 200–1500 °C. The simulation results showed that the residual thermal stress and back temperature of the ZrC-C_GS composites are lower than those of the ZrC-C_DS composites. This work provides an effective strategy for designing and preparing ultra-high temperature composites having both ablation and heat insulation performances by controlling the pore structure and distribution.