Oxidation behavior and ablation resistance of C/C-ZrC-SiC composites prepared by polymer infiltration and pyrolysis

C/C-ZrC-SiC composites were prepared by thermal gradient chemical vapor infiltration (TCVI) and precursor infiltration and pyrolysis (PIP) process. The microstructures and phase compositions of C/C-ZrC-SiC composites after oxidation were analyzed by scanning electron microscopy and X-ray diffraction, respectively. Isothermal oxidation behavior at 1500 ℃, dynamic oxidation behavior from room temperature to 1400 ℃ and long-term ablation resistance of the composites were investigated. The results show that dynamic oxidation behavior from room temperature to 1 400 ℃ can be divided into four stages: mass gain, slow mass loss, severe mass loss and constant. While the isothermal oxidation behavior of C/C-ZrC-SiC at 1500 ℃ can be divided into five stages: mass gain, slow mass loss, constant, severe mass loss and constant. ZrC and SiC trend to be oxidized preferentially and generate ZrO₂and SiO₂, which wrap and protect C/C matrix and fibers partly. After ablated for 1200 s by oxyacetylene flame, the linear and mass ablation rates of composites are 9.27×10^-4 mm·s^-1 and 6.67×10^-4 g·s^-1, respectively. ZrO₂ and SiO₂ are formed by the oxidation of ZrC and SiC, respectively. ZrO₂ can alleviate the thermal-physical and thermal-chemical erosion caused by the oxyacetylene torch, and dense SiO₂ glassy film can seal the defects such as cracks and holes, leading to a good ablation resistance of C/C-ZrC-SiC composites.