热梯度CVI制备大尺寸C/C复合材料的致密化行为

doi:10.15541/jim20140291

摘要/Abstract

摘要：

以整体毡为纤维增强体, 采用外壁恒温控温和内壁恒温控温两种方式, 通过热梯度化学气相渗透(TG-CVI)工艺研究了大尺寸C/C复合材料的致密化行为。结果表明, 外壁恒温控温方式制备的试样密度仅为0.64 g/cm³, 呈现出两边高中间低的特点, 热解碳结构为粗糙层与光滑层相结合。而内壁恒温控温方式制备的试样密度达到0.98 g/cm³, 致密效率相比提高了73.79%, 热解碳结构为具有优异性能的粗糙层结构, 试样内部密度分布均匀。通过与外壁恒温控温相比, 内壁恒温控温方式具有较高的温度和合适的温度梯度, 致密化行为符合理想致密化模型, 能够实现大尺寸C/C复合材料由内至外的正向密度增长, 致密均匀, 致密效率高, 且碳结构优异。

关键词: 大尺寸C/C复合材料, 热梯度化学气相渗透, 致密效率

Abstract:

Using integral carbon felt as reinforced perform, large-scale C/C composites were prepared by thermal gradient-chemical vapor infiltration (TG-CVI) with two temperature controlling ways, namely keeping constant temperature of the inner wall or outer wall of the samples. The results indicated that, for keeping constant temperature of the outer wall, the composite density was merely 0.64 g/cm³, showing high-low-high distribution across the wall. Meanwhile, its structure comprised rough laminar and smooth laminar. For keeping constant temperature of the inner wall, the density of the sample showed evenly distribution across the wall and increased to 0.98 g/cm³, and densification efficiency was 73.79%, higher than that of the former. Under this temperature controlling way, the composite comprised only rough laminar carbon with superior properties. Compared to the outer wall temperature controlling, the composite prepared by the inner wall temperature controlling, needed higher temperature and more appropriate temperature gradient during densification, which was consistent well with the ideal densification model. Moreover, the inner wall temperature controlling way enabled the large-scale C/C composite densification from inner side to outside wall, and achieved uniform density distribution, high densification efficiency and excellent microstructure.

Key words: large-scale C/C composite, thermal gradient-chemical vapor infiltration, densification efficiency

中图分类号:

TB332

李艳, 崔红, 张华坤, 嵇阿琳, 介玉洁. 热梯度CVI制备大尺寸C/C复合材料的致密化行为[J]. 无机材料学报, 2015, 30(2): 153-158.

LI Yan, CUI Hong, ZHANG Hua-Kun, JI A-Lin, JIE Yu-Jie. Densification Behavior of Thermal Gradient CVI of Large-scale C/C Composites[J]. Journal of Inorganic Materials, 2015, 30(2): 153-158.

图/表 8

图1 控温方式示意图

Fig. 1 Schematic diagram of outerwall (a) and innerwall (b) temperature controlling ways of the sample A and B, respectively

图2 A、B试样密度与时间的关系对比图

Fig. 2 Densities of samples prepared under out (A) and inner (B) wall temperature controlling at different densification time

图3 A、B试样不同位置温度随致密化时间变化关系图

Fig. 3 Temperature changes of samples prepared under out (A) and inner(B) wall temperature controlling at different densification time

图4 恒温600 h后A、B试样不同位置SEM照片

Fig. 4 SEM images of sample A and B at different positions after densification for 600 h (a, c and e): Inner wall, central section and outer wall of sample A, respectively, under outer wall temperature controlling; (b, d and f): Inner wall, central section and outer wall of sample B under inner wall temperature controlling

图5 A、B试样不同部位热解碳偏光显微照片

Fig. 5 PLM of pyrocarbon of samples A and B at different positions (a, c and e): Inner wall, central section and outer wall of sample A, respectively, under outer wall temperature controlling, and Ae values were 16°-18°; 16°-18° and 18°-20°, respectively. (b, d and f): Inner wall, central section and outer wall of sample B, respectively, under inner wall temperature controlling, and all Ae values were 18°-20°

图6 不同致密时间后A试样在恒温致密化300 h(a)和600 h(b)时的CT曲线图

Fig. 6 CT curves of sample A under outer wall temperature controlling after densification for 300 h (a) and 600 h (b)

图7 不同致密时间后B试样在恒温致密化300 h(a)和600 h(b)的CT曲线图

Fig. 7 CT curves of sample B under inner wall temperature controlling after densification for 300 h (a) and 600 h (b)

图8 两种试样沉积600 h后CT剖面图

Fig. 8 CT images on cross section of samples under out wall (a) and inner wall (b) temperature controlling after densification for 600 h

参考文献 16

[1]	ZOU ZHI-QIANG, TANG ZHONG-HUA, XIONG JIE.The manufacturing of C/C composite brake disk by means of thermal gradient densification technique.New Carbon Materials, 2000, 15(2): 22-27.
[2]	DELHAES P.Chemical vapor deposition and infiltration processes of carbon materials. Carbon, 2002, 40: 641-657.
[3]	WANG JI-PING, QIAN JUN-MING, QIAO GUAN-JUN, et al.A rapid fabracation of composites by a thermal gradient chemical vapor infiltration method with vaporized kerosene as a precursor.Materials Chemistry and Physics, 2007, 101: 7-11.
[4]	LI HE-JUN.Carbon/carbon composites.New Carbon Materials, 2001, 16(2): 79-80.
[5]	ZHANG WEI-GANG, HU Z J, HÜTTINGRT K J. Chemical vapor infiltration of carbon fiber felt:optimization of densition and carbon microstruction.Carbon, 2002, 40: 2529-2545.
[6]	HU Z. J, ZHANG WEI-GANG, HÜTTINGRT K J, et al. Influence of pressure,temeperature and suface area/volume ratio on the texture of pyrolytic carbon deposited from methane.Carbon, 2003, 41: 749-758.
[7]	PAUW V D, COLLIN A, SEND W, et al.Deposition rates during the early stages of pyrolytic carbon deposition in a hot-wall reactor and the development of textrue.Carbon, 2006, 44: 3091-3101.
[8]	HU ZI-JUN, HÜTTINGR K J. Chemical vapor infiltration of carbon revised Part Ⅱ: Experimental results. Carbon, 2001, 39: 1023-1032.
[9]	ZHANG WEI-GANG, HÜTTINGR K J. Densification of a 2D carbon fiber perform by isothermal,isobaric CVI:Kinetics and carbon microstructurec CVI:Kinetics and carbon microstructure.Carbon, 2003, 41: 2325-2337.
[10]	WU XIAO-JUN, CHENG WEN, QIAO SHENG-RU, et al.Fast densification of thick-walled carbon/carbon composite tubes using electrically coupled chemical vapor infiltration. Carbon, 2013, 57: 371-379.
[11]	SUN GUO-LING, LI HE-JUN, QI LE-HUA, et al.Analysis of unstable temperature field for theraml gradient CVI densification process of C/C composite.Acta Metallurgica Sinica, 2006, 42(10): 1046-1050.
[12]	GUELLALI M, OBERACKER R, HOFFMANN M J, et al.Textures of pyrolytic carbon formed in the chemical vapor infiltration of capillaries.Carbon, 2003, 41: 97-104.
[13]	YIN JIAN, ZHANG HONG-BO, XIONG XIANG, et al.Influence of microstructure of pyrocarbon on ablation performances of C/C composites.Chinese Journal of Materials Research, 2007, 21(1): 10-14.
[14]	YAN GUI-SHEN, LI HE-JUN, ZHANG SHOU-YANG, et al.Densification mechanism of perform with thermal gradient CVI.Acta Materiae Compositae Silica, 2003, 20(2): 64-70.
[15]	DENG JING-YI,LIU WEN-CHUAN,DU HAI-FENG, et al. Control of the deposition temperature in thermal gradient CVI. Carbon Techniques, 1999(6): 22-24.
[16]	LI JIAN-LI,SU ZHE-AN,ZHANG MING-YU, et al.Mehanism of densification of C/C composites fabricated with high density perform.Journal of Inorganic Materials, 2011, 26(7): 711-714.