2.5D浅交直联Cf/Al复合材料的显微组织及弯曲和剪切性能

Microstructure,bending and shear properties of 2.5D shallow cross-linked Cf/Al composites

采用真空压力浸渗法制备体积分数为50% 的2.5D浅交直联Cf/Al复合材料,研究复合材料的显微组织以及室温、高温下弯曲和剪切性能,分析复合材料弯曲和剪切性能的破坏失效机理.结果表明:2.5D浅交直联Cf/Al复合材料经向、纬向显微组织均存在一定的微孔、纤维丝偏聚等缺陷.室温的弯曲强度、弯曲模量、剪切强度分别为268.4 M Pa,75.2 GPa和41.0 M Pa,350℃的弯曲强度、弯曲模量、剪切强度分别为139 M Pa,70.9 GPa和39.2 M Pa,400℃的弯曲强度、弯曲模量、剪切强度分别为97.6 M Pa,68.5 GPa和29.9 M Pa;其中,弯曲失效主要由于内侧面受压导致经向纤维束在压应力作用下被压断,纬向纤维束产生挤压变形;外侧面受拉处随测试温度升高复合材料拉伸破坏现象不明显;而剪切破坏首先出现在基体与纤维束界面损伤处,室温下纤维束被拔出,断口不平齐,350,400℃时纤维束断口呈现45°破坏;经向纤维束屈曲与纬向纤维束挤压变形程度随测试温度升高越来越严重.

2.5 D shallow cross-linked Cf/Al composites with volume fraction of 50%were fabricated by vacuum pressure infiltration.The microstructure,bending and shear properties at room and high temperature were studied.The failure mechanism of bending and shear properties of the composites were analyzed.The results indicate that the warp and weft microstructures of 2.5 D shallow cross-linked Cf/Al composites have some defects such as microvoid and fiber aggregation.The bending strength,bending modulus and shear strength of the composites at room temperature are 268.4 MPa,75.2 GPa and 41.0 MPa,respectively.The bending strength,bending modulus and shear strength of the composites at 350℃ are 139 MPa,70.9 GPa and 39.2 MPa,respectively.The bending strength,bending modulus and shear strength of the composites at 400℃ are 97.6 MPa,68.5 GPa and 29.9 MPa,respectively.The bending failure is mainly caused by the compressive stress on the inner surface,which leads to press fracture of the warp fiber bundle and the extrusion deformation of the weft fiber bundle.Tensile failure of composites is not obvious with the increase of testing temperature at the outer side tension.Shear failure occurs first in the damage interface of the matrix and fiber bundle,the fiber bundle is pulled out and the fracture surface is not at the same level at room temperature,the fracture of the fiber bundle shows 45°failure at 350,400℃.The buckling of the warp fiber bundle and the extrusion deformation degree of the weft fiber bundle become more and more serious with the increase of the test temperature.