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以天然气作为碳源,以2D针刺碳毡作为预制体,采用热梯度化学气相渗透工艺制备2D-C/C复合材料。采用偏光显微镜(PLM)和扫描电子显微镜(SEM)观察材料的显微组织,采用万用力学试验机测试热处理前后材料的弯曲行为,讨论材料的断裂机制。结果表明,热解炭基体表现为纯净光滑层(SL)特征,包含大量褶皱层片结构和一些层间微裂纹。随着材料密度的降低,材料强度降低,断裂韧性略有提高;经过2500°C热处理后,基体中层间微裂纹数量大量增加,在加载过程中SL基体中发生了更多的裂纹偏转,材料强度大幅度降低,其断裂韧性明显升高,从沉积态时的脆性断裂转变为理想的假塑性断裂。
2D-C / C composites were prepared by thermal gradient chemical vapor infiltration using natural gas as carbon source and 2D acupuncture carbon felt as preform. The microstructure of the material was observed by polarized light microscopy (PLM) and scanning electron microscopy (SEM). The bending behavior of the material before and after heat treatment was tested by universal mechanical testing machine. The fracture mechanism of the material was discussed. The results show that the pyrolytic carbon matrix is characterized by pure smooth layer (SL), including a large number of folds and some interlaminar microcracks. As the density of the material decreases, the strength of the material decreases and the fracture toughness slightly increases. After 2500 ° C heat treatment, the amount of micro-cracks in the middle layer of the substrate increases greatly, and more crack deflections occur in the SL matrix during loading. The strength is greatly reduced, the fracture toughness is obviously increased, and the transition from the brittle fracture in the as-deposited state to the ideal pseudoplastic fracture.