电泳沉积CNTs掺杂C/C复合材料的微观组织与弯曲性能

doi:10.15541/jim20150301

摘要/Abstract

摘要：

采用电泳沉积(EPD)在1k碳布表面均匀加载了碳纳米管(CNTs), 借助化学气相沉积(CVD)致密化碳布叠层预制体, 制备了EPD CNTs掺杂的二维(2D)碳/碳(C/C)复合材料。研究了EPD CNTs对2D C/C复合材料致密化过程、微观组织和弯曲性能的影响。研究结果表明: EPD CNTs在碳纤维表面呈现平面内高密度、杂乱取向分布特征, 该形貌CNTs降低了热解炭在碳纤维预制体内的沉积速率, 诱导了高石墨微晶堆垛高度(L_c)、低(002)晶面面内方向上的沉积有序度(L_a)热解炭的形成; EPD CNTs的掺杂可提高C/C复合材料的弯曲强度和模量: 当CNTs含量为0.74wt%时, 复合材料弯曲强度和模量可达150.83 MPa和23.44 GPa, 比纯C/C复合材料提高了31.4%和13.9%; 继续提高CNTs含量, 复合材料弯曲强度降低, 这与过高含量EPD CNTs导致复合材料密度降低有关; 同时, EPD CNTs的掺杂使得C/C复合材料断裂模式由脆性断裂转变为假塑性断裂, 复合材料断裂塑性的提高是由于EPD CNTs造成的碳基体结构的变化以及碳纤维的大量拔出。

关键词: C/C复合材料, 电泳沉积, 碳纳米管, 微观组织, 弯曲性能

Abstract:

Carbon nanotubes (CNTs) were deposited uniformly on 1 k carbon cloth by electrophoretic deposition (EPD). After that, CNT-doped clothes were stacked and densified by pyrocarbon via chemical vapor depositon (CVD) to prepare two dimensional (2D) carbon/carbon (C/C) composites. Effects of EPD CNTs on CVD process, microstructure and flexural property of 2D C/C composites were investigated. Results show that EPD CNTs are dispersed in the plane parallel to carbon fiber surface with random orientations and a high distribution density, leading to the decrease of densification rate of EPD CNT-doped C/C composites and the formation of pyrocarbon with high L_cand small L_a values. EPD CNTs increase the flexural strength and modulus of C/C composites and the improvements can reach 31.4% and 13.9% when the loading of EPD CNTs is 0.74wt%, with corresponding flexural strength and modulus being 150.83 MPa and 23.44 GPa, respectively. Further increasing the dope of EPD CNTs can decrease the flexural property of C/C composites, resulting in their bulk density decrease. The introduction of EPD CNTs changes the fracture mode of C/C composites from brittle fracture to pesudo-plastic fracture, which is related to the change of pyrocarbon in microstructures and the resulted carbon fiber pullout.

Key words: C/C composite, electrophoretic deposition, carbon nanotube, microstructure, flexural property

中图分类号:

TB332

齐乐华, 舒扬, 李贺军, 黎云玉, 马海丽, 宋强. 电泳沉积CNTs掺杂C/C复合材料的微观组织与弯曲性能[J]. 无机材料学报, 2016, 31(2): 201-206.

QI Le-Hua, SHU Yang, LI He-Jun, LI Yun-Yu, MA Hai-Li, SONG Qiang. Microstructures and Flexural Properties of C/C Composites Doped with CNTs by Electrophoretic Deposition[J]. Journal of Inorganic Materials, 2016, 31(2): 201-206.

图/表 9

图1 EPD用CNTs的TEM形貌和微观组织照片

Fig. 1 TEM image of CNTs used in this work for EPD

图2 经不同时间EPD CNTs的碳布表面SEM照片

Fig. 2 SEM images of carbon fiber clothes doped with CNTs by EPD for different time (a) 0 s; (b) 20 s; (c) 40 s; (d) 60 s

图3 不同量EPD CNTs掺杂C/C复合材料表观密度随CVD时间的变化曲线

Fig. 3 Bulk density of EPD CNTs doped C/C samples as a function of CVD time

图4 不同量EPD CNTs掺杂C/C复合材料的PLM微观组织照片

Fig. 4 Microstructures by PLM of EPD CNTs doped C/C samples (a) C/C; (b) CNT0.35wt%-C/C; (c) CNT0.74wt.%-C/C; (d) CNT1.06wt.%-C/C

图5 不同量EPD CNTs掺杂C/C复合材料碳基体的XRD图谱

Fig. 5 XRD patterns of carbon matrices of EPD CNTs doped C/C samples

表1 四种C/C复合材料的晶格参数

Table 1 Lattice parameters of the four kinds of C/C composites

Samples	2θ/(°)	d₀₀₂/nm	L_c/nm
Pure-C/C	25.96	0.3431	5.86
CNT_0.35wt%-C/C	25.98	0.3427	6.16
CNT_0.74wt%-C/C	26.04	0.3420	15.18
CNT_1.06wt%-C/C	25.97	0.3429	5.86

表2 四种C/C复合材料的弯曲性能

Table 2 Flexible performances of the four kinds of C/C composites

Composites	Bulk density/ (g•cm^-3)	Flexible modulus/GPa	Flexible strength/MPa
Pure-C/C	1.64±0.01	20.58±0.68	114.75±12.01
CNT_0.35wt%-C/C	1.63±0.01	21.69±0.73	125.82±14.36
CNT_0.74wt%-C/C	1.61±0.02	23.44±0.97	150.83±13.61
CNT_1.06wt%-C/C	1.55±0.02	22.08±0.79	126.87±12.59
CNT_1.31wt%-C/C	1.45±0.03	19.82±0.67	117.56±10.12

图6 不同C/C复合材料弯曲载荷-位移曲线

Fig. 6 Load-displacement curves of different C/C composites in flexural tests

图7 纯C/C(a,b)和EPD CNTs掺杂C/C复合材料(c~f)弯曲断口的SEM照片

Fig. 7 SEM images of flexural fracture surface of pure C/C (a,b) and EPD CNTs doped C/C (c-f) composites

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