Zirconium carbide skeleton reinforced pyrocarbon composites with tunable mechanical strength, thermophysical properties and ablation resistance

Zirconium carbide skeleton reinforced pyrocarbon (ZrC-C) composites with different weight ratio of ZrC/PyC were designed and prepared by hot-pressing sintering and isothermal chemical vapor infiltration. Their thermal expansion coefficients at 200–1500 ℃ were controlled in the range of 4.95 × 10⁻⁶–7.34 × 10⁻⁶ ℃⁻¹. As the weight ratio of ZrC/PyC increased from 1.4 to 2.4, the compressive strengths of ZrC-C composites along the Z direction increased from 188.0 ± 6.9–252.6 ± 11.2 MPa. After ablation for 60 s using oxyacetylene torch with a heat flux of 2.4 MW/m², the surface temperatures of the samples increased from 2177 to 2272 ℃, but their linear and mass ablation rates decreased from 5.290 ± 1.267 to −0.766 ± 0.587 μm/s and 3.504 ± 0.375 to 0.451 ± 0.138 mg/s, respectively. High-content ZrO₂ skeleton formed by the oxidation of ZrC could further restrain the composite consumption. Finite element simulation results showed that the thermal stresses increased with the increase of the weight ratios of ZrC/PyC.