C/C基体密度对C/C-SiC-ZrC复合材料性能的影响

分别以密度为1.26 g/cm~3和1.46 g/cm~3的C/C复合材料作为基体材料,用有机硅和乙酸锆作为先驱体,采用先驱体浸渍裂解法(precursor infiltration pyrolysis,PIP)制备C/C-SiC-ZrC复合材料,利用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱分析(EDS)等检测手段分析该复合材料的成分和微观结构,研究C/C基体密度对材料抗压强度、线膨胀系数以及抗烧蚀性能的影响。结果表明,C/C基体密度为1.46 g/cm~3时C/C-SiC-ZrC复合材料的抗压强度较高(146.36 MPa)、线膨胀系数较小。C/C基体密度为1.26 g/cm~3的C/C-SiC-ZrC复合材料具有更优的抗烧蚀性能,经过30 s烧蚀后,其质量烧蚀率和线烧蚀率分别为-2.9×10-4g/s和1.7×10-3 mm/s,这主要是因为C/C基体密度较低时,材料中的陶瓷含量更高,当烧蚀发生时,能更快地在材料表面形成SiO_2-ZrO_2氧化物薄膜,从而减缓材料内部基体的进一步烧蚀。

Effect of C/C density on the properties of C/C-SiC-ZrC composites

C/C-SiC-ZrC composites were fabricated by precursor infiltration pyrolysis (PIP) using C/C composites with the densities of 1.26 g/cm3 and 1.46 g/cm3, respectively, as the matrix materials, and organic silicon and zirconium acetate as the precursors. The composition and morphology of the composites were characterized by X-ray diffraction meter (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The effect of C/C density on compression strength, coefficient of linear expansion and ablation resistance were investigated. The results showed that the C/C-SiC-ZrC composites with C/C density of 1.46 g/cm3 had the superior compression strength and lower coefficient of linear expansion. After ablation for 30 s, the C/C-SiC-ZrC composite with C/C density of 1.26 g/cm3 showed the better ablation resistance. Its mass and linear ablation rates were ?2.9×10?4 g/s and 1.7×10?3 mm/s, respectively. This was mainly because the content of ceramic is higher in C/C-SiC-ZrC composites when the density of C/C was lower. As a result, the SiO2-ZrO2 oxides film were formed on the surface of the composites more quickly when the ablation occurred. Then it could retard the further ablation of the substrate.