C/C Composites Research Center, Northwestern Polytechnical University
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DOI:
10.7502/j.issn.1674-3962.2015.06.02
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Abstract:
C/C-ZrC-SiC-ZrB2 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 1400 ℃ could 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 ℃ could 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 ZrO2 and 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 were 9.27×10-4 mm?s-1 and 6.67×10-4 g?s-1, respectively. ZrO2 and SiO2 were 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.