以乙醇和甲烷为前驱体, 采用化学气相渗透工艺制备了三维五向编织C/C复合材料。利用偏光显微技术分析了复合材料的微观结构, 考察了复合材料的静态弯曲性能和疲劳行为, 研究了不同循环加载周期对复合材料弯曲强度和力学行为的影响。结果表明: 采用混合前驱体可成功制备高织构3D C/C复合材料, 材料的平均弯曲强度为379.2 MPa, 其疲劳极限为静态弯曲载荷的80.3%。加载循环应力后, C/C复合材料的弯曲强度在不同周次均有所提升, 循环10 ⁵周后弯曲强度的增幅达16.8%。材料弯曲承载时的“屈服区”随着循环次数的增加出现先增大后减小的变化趋势, 这与材料疲劳过程中纤维与基体、基体与基体的结合状态有关。

Three-dimensional five-way braided C/C composites were prepared by chemical vapor infiltration using ethanol and methane as precursors. Their microstructure of the composites was analyzed by polarizing microscope. The static bending properties and fatigue behavior of prepared composites were investigated. Effects of loading cycles on bending strength and mechanical behavior of the prepared composites were studied. Results show that high texture C/C composites can be successfully fabricated by using mixed precursors. Average bending strength of the composites is 379.2 MPa, and their fatigue limit is 80.3% of the static bending load. Under cyclic loading, the flexural strength of C/C composites increases in different cycles. The bending strength is increased by 16.8% after 10 ⁵ cycles. "Yield zone" of the bending bearing capacity of the material increases firstly and then decreases with the increase of the cyclic loading, which is related to the bonding state of fiber-matrix and matrix-matrix in the fatigue process.