本文制备了高密度三维针刺炭/炭复合材料,研究了该材料在室温和高温下的弯曲性能,并从宏、细观角度研究了材料的变形与失效机理。结果表明,三维针刺炭/炭复合材料具有好的抗弯曲性能,400℃以下的载荷-挠度曲线呈线弹性和脆性破坏特征；而更高温度下的曲线表现出明显的韧性和塑性失效。由于氧化作用的加重,材料的弯曲性能随着温度的升高而显著减小。材料呈现锯齿状断裂特征,在500℃以下,主要的损伤形式表现为基体开裂,90°纤维/基体脱粘,0°纤维的局部扭曲和断裂；而在更高温度下,复合材料的氧化特征更加明显,纤维和基体间的界面粘结性能显著下降。
A 3D needle-punched C/C composite with a high density was fabricated and its bend properties were investigated at room and high temperatures. Macro-fracture and SEM micrographs were examined to understand the deformation and failure mecha-nism. Results show that the load-deflection curves below 400 ℃ exhibit a linear elastic and brittle fracture failure, while the curves at temperatures above 500 ℃ show an obvious tough and plastic failure. The bend strength and modulus decrease significantly with increasing temperature due to severe carbon oxidation. Below 500 ℃, the main damage to the composite is in the form of matrix cracking, 90° fiber/matrix debonding, local twisting and fracture of the 0° fibers. Above 500 ℃, the oxidation of the composite is significant and the interfacial adhesion between fibers and matrix is decreased significantly.
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