摘要: |
为制备大尺寸厚壁C/C-UHTCs复合材料构件,以细编穿刺碳纤维预制体为增强体,采用沥青浸渍碳化和HfC前驱体浸渍裂解结合的全液相工艺,制备了不同陶瓷含量的C/C-HfC复合材料,研究其微观结构和力学性能。结果表明,全液相工艺改善了HfC陶瓷的引入深度,浸渍碳化工艺改善了材料致密度,HfC在纤维预制体空隙中呈现出棋盘状的岛形分布。细编穿刺预制体和适当含量HfC陶瓷提供了复合材料的优异力学性能,断口微观形貌观察到大量纤维拔出。C/C-HfC在常温下拉伸强度达到了236~249MPa,呈现出弹性破坏行为;弯曲强度达到312.7~298.5MPa,并呈现出假塑性行为;压缩强度达到了300~387MPa。对C/C-HfC的高温拉伸性能进行分析,由于热膨胀失配、残留氧还原、晶粒尺寸增大等原因,复合材料在高温下力学性能下降明显,强度降幅达57.1%。 |
关键词: HfC;C/C-HfC复合材料;C/C基体改性;力学性能 |
基金项目: |
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Preparation and Mechanical Properties of UHTCs Modified C/C Composites by An All-liquid Phase Method |
Sun Xiangyu Li Ruizhen Xie Dong
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Xi’an Aerospace Composite Research Institute
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Abstract: |
For the preparation of large-size and thick-wall C/C-UHTCs components, C/C-HfC composites with different ceramic contents were prepared by a combined all-liquid process of pitch impregnation and carbonization (PIC) and precursor infiltration and pyrolysis (PIP) using pierced carbon fiber preforms as reinforcement, and their microstructure and mechanical properties were studied. The results showed that the all-liquid-phase process improved the introduction depth of HfC ceramics, and PIC process improved the material densities. HfC showed a tessellated island-shaped distribution in the fiber preform voids. Pierced carbon fiber preforms and appropriate content of HfC ceramics provided excellent mechanical properties of the composites, and a large amount of fiber pullout was observed in the fracture micromorphology. At room temperature, the tensile strength of C/C-HfC reached 236~249MPa, showing elastic damage behavior. The flexural strength reached 312.7~298.5MPa and exhibited pseudoplastic behavior. The compression strength reached 300~387MPa. Tensile properties of C/C-HfC at high temperature were analyzed, results showed that mechanical properties of the composites decreased significantly at high temperatures due to thermal expansion mismatch, residual oxygen reduction, and grain size increase, with a strength decrease of 57.1%. |
Key words: HfC;C/C-HfC composites;C/C matrix modification;mechanical properties |