预浸料的超薄化对碳纤维/环氧树脂复合材料拉伸破坏行为的影响

采用自主研发的碳纤维（CF）宽展设备，将12K CF宽展预浸制备成0.02 mm和0.10 mm厚的CF/环氧树脂（EP）预浸料，利用模压工艺制成1 mm厚的单向层合板。利用万能试验机、声发射装置和高速照相机组成的集成系统测试其抗拉强度、加载过程中试样内部的损伤情况及断裂破坏时样品宏观形貌的变化。用SEM观测其拉伸断口形貌。分别用超景深显微镜、金相显微镜观测记录CF/EP复合材料预浸料和单向层合板中CF的排布状态以表征薄层化过程中CF和EP的分布状态对CF/EP复合材料拉伸性能的影响。结果表明:薄CF/EP复合材料预浸料中CF的排布更加均匀，制成的CF/EP复合材料单向层合板试样中层间树脂富集区的尺度明显小于厚CF/EP复合材料预浸料制成的试样，试样的抗拉强度提高了15%；薄CF/EP复合材料预浸料制成层合板试样的拉伸宏观断口形貌中分层劈裂现象减少，集束性增强，微观断口形貌中未发现横贯横截面的穿透裂纹。 

Effect of ultra-thinning of prepreg on tensile failure behavior of carbon fiber/epoxy resin composites

The self-developed carbon fiber wide-spreading equipment was used to pre-dip 12K carbon fiber(CF) into wide CF/epoxy(EP) prepreg with 0.02 mm and 0.10 mm thickness, and the unidirectional laminate of 1 mm thickness was fabricated by molding process. The integrated system including universal testing machine, acoustic emission device and high-speed camera was used to test the tensile strength, the damage inside the sample during loading and the macroscopic morphology of the sample during fracture failure. The tensile fracture morphology was observed by SEM. The super-depth microscope and metallographic microscope were used to observe the arrangement of CF in CF/EP composite prepreg and unidirectional laminate to characterize the influence of CF and EP distribution on the tensile properties of CF/EP composites during thinning. The results show that the CF is more uniform in the thin CF/EP composite prepreg, and the scale of the inter-layer resin enrichment zone in the CF/EP composite unidirectional laminate is much smaller than the laminate made of thick CF/EP composite prepreg. The tensile strength of CF/EP composites sample is increased by 15%. The delamination and splitting phenomenon of the laminate made of thin CF/EP composite prepreg is reduced in the macroscopic fracture morphology, and the clustering property is enhanced. No penetration cracks across the cross section are found in the micro fracture morphology of laminate made of thin CF/EP composite prepreg.