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采用炭纤维平纹织物和精细Z pin制备了新型3D炭纤维预制件,炭基体采用等温化学气相沉积和高温煤沥青高压浸渍炭化制备。短梁剪切试验和开口拉剪试验用来表征Z pin增强体对剪切破坏模式的影响。短梁剪切失效模式为假塑性,而拉剪失效模式为非假塑性破坏。分析了产生此现象的机制,短梁剪切假塑性失效由炭/炭复合材料叠层中纤维束内、纤维束间和叠层间微裂纹扩展形成,而产生拉剪失效的单一层间裂纹扩展不引起宏观假塑性现象。采用Z pin作为提高层间剪切强度的增强体间隔1.5mm比间隔2.5mm可提高剪切强度40%～50%,该技术将成为3D炭/炭复合材料预制体制备更为先进的技术。
A novel 3D carbon fiber preform was prepared by using carbon fiber plain weave and fine Z pin. The carbon matrix was prepared by isothermal chemical vapor deposition and high temperature coal tar pitch impregnation carbonization. The short-beam shear test and the open-ended shear test are used to characterize the effect of Z pin reinforcements on shear failure modes. Short beam shear failure mode is pseudoplastic, while shear failure mode is non-pseudoplastic damage. The mechanism of this phenomenon was analyzed. The pseudoplastic failure of short-beam shear was caused by the propagation of microcracks in the fiber bundles, fiber bundles and laminates in the carbon / carbon composite laminates, Expansion does not cause macroscopic pseudoplastic phenomenon. The use of Z pin as an enhancer for increasing the interlaminar shear strength increases the shear strength by 1.5 to 1.5 mm and increases the shear strength by 40 to 50%. This technology will become a more advanced technology for the preparation of 3D carbon / carbon composite preforms.