混合前驱体制备高织构三维C/C复合材料的微观结构及疲劳行为

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 10⁵ 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.