C/C-Cu复合材料的烧蚀形貌和烧蚀机理

以PAN预氧化纤维整体毡为增强体,经碳化、等温CVI致密化后制备多孔的C/C复合材料预制体,利用气体压力浸渗法将Cu引入C/C预制体中制备C/C-Cu复合材料。采用氢氧(H2-O2)焰考核C/C-Cu复合材料的烧蚀性能,经扫描电镜和电子能谱对不同烧蚀区域的微观结构和成分进行分析,结果表明:预制体密度为0.96 g/cm3的C/C-Cu复合材料的线烧蚀率和质量烧蚀率分别为4.75μm/s、0.223 mg/s,烧蚀性能优良;其烧蚀表面具有不同的宏观形貌,在烧蚀中心区产生了明显的凹坑,主要烧蚀机制为C/C预制体的氧化和铜基体的机械冲刷;烧蚀过渡区聚集了大量的铜基体,其烧蚀机制为Cu的热氧化和机械冲刷;烧蚀边缘区材料表面变黑,主要因为C/C的氧化。为了提高C/C-Cu的烧蚀性能,需要发挥C/C预制体的"钉扎"作用,阻止Cu在高温下被气流冲刷而发生流动。

Ablative Morphology and Mechanism in Different Regions of C/C-Cu Composites

Using PAN-based pre-oxidized fiber integral felt as reinforcement, the porous C/C preforms were fabricated by carbonization and isothermal CVI, and then C/C-Cu composites were manufactured by gas pressure infiltration technique which introduced copper into the porosity of C/C preforms. The ablative properties of C/C-Cu composites were tested by H₂-O₂ ablation method. The micro-morphology and constitutions in different ablative regions were analyzed by SEM and EDS. The results indicate that the ablative performance of C/C-Cu composites with 0.96g/cm³ density is excellent due to low linear and mass ablation rate. The ablative macro-morphology is composed of significant pit as central region in which the ablative mechanisms are oxidation of C/C preform and mechanical erosion of copper. Thermal oxidation and mechanical erosion of copper result in copper concentration in transition region, and black color surface in marginal region is due to oxidation of C/C preform. In order to improve the ablative performance of C/C-Cu, "pinning" effect of C/C preform should play an important role which can prevent copper from flowing by flame at high temperature.