Mechanical behaviors of carbon/carbon composites under the high-temperature

The hightemperature flexural properties of two dimensional (2D) C/C laminates and three dimensional (3D) integral braided C/C composites were tested at 1?700?℃ and room temperature by three point bending tests. The damage features were analyzed by scanning electron microscopy (SEM). It is concluded that the flexural properties of C/C at elevated temperature are superior to these at room temperature, specifically, the strength increases by more than 45?% and the modulus increases by up to 15.3?%. Moreover, the braided integrity structures applied in 3D C/C improve the stress states, change the fractural patterns of the materials, and therefore result in the superior mechanical properties to those of 2D C/C laminates. Fiber breakage predominates the fracture of 3D C/C composites while delamination and matrix cracks control 2D C/C damage. Finally, the interfaces became stronger at high temperature, leading to the increased flexural strength and modulus as well as the diversified failure mode of 3D C/C. The 3D C/C samples failed from staggered rupture to sudden break as the temperature increased.