穿刺结构参数对C/C复合材料拉伸性能的影响

Influence of punctured structure parameters on tensile performance of C/C composite

采用不同间距、不同根数的纤维束穿刺成型炭纤维预制体,经进一步化学气相沉积、沥青浸渍-高压炭化致密制备穿刺C/C复合材料。拉伸性能测试结果表明,穿刺间距2.1mm、穿刺束纤维根数为12K的C/C复合材料获得高的拉伸强度,Z向拉伸强度131.4MPa,XY向拉伸强度111.3MPa;随着穿刺间距减小、穿刺丝束纤维根数增加,Z向纤维含量增加,Z向拉伸强度明显提高。穿刺C/C复合材料1800℃真空条件下的拉伸强度与室温相当,拉伸模量低于室温,延伸率高于室温;常温拉伸断口较平整,且纤维/基体间的裂纹明显,而高温拉伸断口参差不齐,纤维及基体断面粗糙,呈现出假塑性断裂特征。

Carbon fiber bundles with different distance and fiber content were punctured to form carbon fiber preforms. The preforms were densified by CVI and pitch impregnation-high pressure carbonization process. The results show that the material punctured by 12K bundles with a distance of 2.1 mm displays tensile strength of 131.4MPa along Z-direction and 111.3 MPa along XYdirection. With the bundle distance decreasing and the fiber amount of punctured bundle increasing,increase of the Z-directional carbon fiber volume result in increasing tensile strength along Z-direction obviously. The tensile strength under vacuum and 1 800℃ condition is similar to that under room temperature; the tensile modulus is lower and the tensile elongation is higher than that under room temperature. The tensile fracture surface of sample tested at room temperature is flat and smooth; there are obvious cracks in the interface between fiber and matrix. On the contrary,the tensile fracture surface of the sample tested at 1800℃ is rough,both the fibers and matrix fracture surface are rough,which present pseudoplastic characters.