高温炭化处理对三维五向碳/酚醛编织复合材料拉伸性能的影响

对未经炭化和经不同温度炭化处理后的三维五向碳/酚醛编织复合材料进行了纵向和横向拉伸实验, 获得了拉伸应力-应变曲线, 并确定了材料的拉伸强度、 拉伸模量、 破坏应变和泊松比等主要力学性能, 分析了这类材料经不同温度炭化处理后拉伸力学性能的变化规律。对试件拉伸实验后的破坏断口进行了宏观和微观分析, 探讨了材料的变形和破坏机理。实验结果表明: 随炭化处理温度的增加, 三维五向碳/酚醛编织复合材料的纵向、 横向拉伸强度和拉伸模量均呈先降后升的趋势, 存在一个转折温度, 超过该温度, 材料的拉伸强度和拉伸模量从下降变为上升, 但拉伸模量的变化幅度较小; 但是, 随着炭化温度的升高, 材料的破坏应变是逐渐降低的。通过形貌观察和树脂热分解机理分析, 认为在不同的炭化处理温度下, 材料的细观组织结构演变存在明显的差异, 因此造成了材料力学性能的变化。 

Effect of high temperature carbonization on the tensile properties of integrally-braided 5D carbon/phenolic composites

The longitudinal and transverse tensile properties were tested for integrally -braided 5D carbon/phenolic composites carbonized at different temperatures in comparison to the virgin material.The tensile stress-strain curves were obtained and the principal mechanical properties(tensile strength,tensile modulus,failure strain,Poisson's ratio) were determined.A phenomenological relationship between tensile properties and carbonization temperature was established.The fracture morphology and microstructure after tension were observed to further understand the deformation and the failure mechanism.Both longitudinal and transverse tensile strength and modulus show a transition from decrease to increase with temperature rise around a certain temperature point,and the magnitude of modulus change is relatively small.The failure strain exhibits monotonic gradual decrease.The property change is supposed to be correlated with the microstructural evolution of the phenolic matrix upon carbonization at different temperatures.