展宽布/网胎针刺C/C复合材料制备及力学性能

Preparation and mechanical properties of spreading cloth/carbon fiber felt needled C/C composites

为提高针刺碳/碳(C/C)复合材料致密化效率和承载性能,分别设计了16 mm展宽布与网胎交替叠层的针刺预制体(B-NPs)、8 mm展宽布与网胎交替叠层的针刺预制体(H-NPs)及外层采用B-NPs结构、内层采用H-NPs结构的针刺预制体(T-NPs),联合化学气相渗透和浸渍-碳化工艺制备了3种针刺C/C复合材料。采用阿基米德排水法和X射线计算机断层扫描(Micro-CT)技术对3种针刺C/C复合材料的致密化效率、孔隙率和孔隙分布进行了统计,并开展了常温下三点弯曲力学性能测试。结果表明:随着展宽纱线宽度的增加,针刺C/C复合材料致密化效率得到提高,内部孔隙率有所下降。在相同的致密化时间内,B-NPs增密效果最佳,密度达到1.42 g/cm^(3),孔隙率仅为10.67%。三点弯曲载荷下,3种材料均表现出脆性破坏,其中T-NPs的弯曲强度和弯曲模量分别为173.04 MPa和20.66 GPa,具有优异的抗弯性能。3种材料的初始破坏位置均发生在针刺纤维束附近,其中低孔隙率的B-NPs针刺纤维束和碳布层破坏以纤维断裂为主;高孔隙率的H-NPs纤维/基体界面结合能力差,碳布层的破坏以纤维/基体界面脱粘和纤维拔出为主导。

In order to improve the densification efficiency and load-bearing performance of needle punched carbon/carbon(C/C)composites,needle punched preforms B-NPs with 16 mm spreading coth and felt tire alternating layers,needle punched preforms H-NPs with 8 mm spreading coth and felt tire alternating layers,and needle punched preforms T-NPs with B-NPs structure on the outer layer and H-NPs structure on the inner layer were designed.Three types of needle punched C/C composites were prepared by combining chemical vapor infiltration and impregnation-carbonization processes.The densification efficiency,porosity and pore distribution of three kinds of needle punched C/C composites were statistically analyzed by Archimedes drainage method and X-ray computed tomography(Micro-CT)technology,and three-point bending mechanical properties were tested at room temperature.The results indicate that as the width of the widened yarn increases,the densification efficiency of the needle punched C/C composite material is improved,and the internal porosity decreases.Within the same densification time,B-NPs have the best densification effect,with a density of 1.42g/cm^(3) and a porosity of only 10.67%.Under three-point bending load,the three materials all show brittle failure.The bending strength and flexural modulus of T-NPs are 173.04 MPa and 25.03 GPa respectively,which have excellent bending resistance.The initial failure of the three materials all occurs near the needle punched fiber bundle,with fiber fracture being the main failure mode for the low porosity B-NPs needle punched fiber bundle and carbon cloth layer;High porosity H-NPs fiber/matrix interface has poor bonding ability,and the failure of carbon cloth layer is dominated by fiber/matrix debonding and fiber pullout.