高定向石墨块的控制制备及其导热性能影响因素研究

doi:10.15541/jim20160480

无机材料学报 ›› 2017, Vol. 32 ›› Issue (6): 587-595.DOI: 10.15541/jim20160480 CSTR: 32189.14.10.15541/jim20160480

高定向石墨块的控制制备及其导热性能影响因素研究

袁观明¹, 薛政¹, 崔正威¹, 董志军¹, 李轩科¹, 张中伟², 王俊山²

(1. 武汉科技大学省部共建耐火材料与冶金国家重点实验室, 武汉430081; 2. 航天材料及工艺研究所, 北京100076)

收稿日期:2016-08-29 修回日期:2016-10-14 出版日期:2017-06-20 网络出版日期:2017-05-27
作者简介:袁观明(1978–), 男, 博士, 副教授. E-mail: yuanguanming@wust.edu.cn
基金资助:
国家自然科学基金(91016003 & 51372177);湖北省教育厅科学研究计划(Q20141104)

Controlled Preparation and Thermal Conductivity of Highly Oriented Graphite Blocks

YUAN Guan-Ming¹, XUE Zheng¹, CUI Zheng-Wei¹, DONG Zhi-Jun¹, LI Xuan-Ke¹, ZHANG Zhong-Wei², WANG Jun-Shan²

(1. Wuhan University of Science and Technology, The State Key Laboratory of Refractories and Metallurgy, Wuhan 430081, China; 2. Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China)

Received:2016-08-29 Revised:2016-10-14 Published:2017-06-20 Online:2017-05-27
About author:YUAN Guan-Ming. E-mail: yuanguanming@wust.edu.cn
Supported by:
National Natural Science Foundation of China (91016003 & 51372177);Hubei Provincial Department of Education Science Research Project (Q20141104)

摘要/Abstract

摘要：

以廉价易得的高结晶度天然鳞片石墨(NG)和中间相沥青为原料, 采用中温热模压一次成型再高温炭化、石墨化处理可以制备高密度、高定向、高导热石墨块体材料。XRD、SEM和PLM分析表明该石墨块具有高度择优取向结构, 其内部石墨片垂直热压方向有序堆积排列。原料中鳞片石墨和沥青粘结剂的组成和配比以及制备工艺参数等对所制石墨材料的面向导热性能有显著影响。采用86wt%+32目鳞片石墨和14wt%AR中间相沥青在500℃、10 MPa下热模压成型的炭块经1000℃炭化、2800℃石墨化后样品的热物理综合性能较好, 其体积密度达到1.91 g/m³以上, 室温面向热导率为550 W/(m·K), 3000℃石墨化室温面向热导率高达620 W/(m·K)。

关键词: 石墨块, 高定向, 控制制备, 导热性能

Abstract:

Using cheap and available natural flake graphite with high crystallinity and mesophase pitch as raw materials, graphite block materials with high bulk density, highly preferred orientation and high thermal conductivity, were prepared by a hot-press molding at mild temperatures and subsequent carbonization and graphitization treatments at high temperatures. XRD, SEM and PLM analyses indicate that the prepared graphite block has a highly preferred structural orientation, the graphitic layers of the graphite flakes inside are clearly oriented perpendicular to the hot-pressing direction. The components of various sized flake graphite and different types of pitch binders, and the proportions of raw materials, as well as the preparation process parameters (including hot-pressing temperature and pressure, heat treatment temperature, etc.), have great influences on the room-temperature in-plane thermal conductivity of the resultant graphite blocks. Graphitized blocks prepared from 86wt% NG (+32 mesh) and 14wt% AR mesophase pitch through hot-pressed at 500℃ at a fixed pressure of 10 MPa for 5 h and subsequently underwent 1000℃ carbonization and 2800℃ graphitization, have a good comprehensive thermophysical property. Their bulk density reaches above 1.91 g/m³, and room-temperature in-plane thermal conductivity is measured as high as 550 W/(m·K), and improved to 620 W/(m·K) after 3000℃ graphitization treatment.

Key words: graphite block, high orientation, controlled preparation, thermal conductivity property

中图分类号:

TB303

袁观明, 薛政, 崔正威, 董志军, 李轩科, 张中伟, 王俊山. 高定向石墨块的控制制备及其导热性能影响因素研究[J]. 无机材料学报, 2017, 32(6): 587-595.

YUAN Guan-Ming, XUE Zheng, CUI Zheng-Wei, DONG Zhi-Jun, LI Xuan-Ke, ZHANG Zhong-Wei, WANG Jun-Shan. Controlled Preparation and Thermal Conductivity of Highly Oriented Graphite Blocks[J]. Journal of Inorganic Materials, 2017, 32(6): 587-595.

图/表 15

图1 鳞片石墨涂覆沥青粘结剂(a)前(b)后的SEM照片

Fig. 1 SEM images of natural graphite flakes (a) before and (b) after coated by mesophase pitch binder

图2 高定向石墨块2800℃石墨化样品的(a)光学照片、(b)织构示意图及其(c)不同面的XRD谱图

Fig. 2 (a) Optical photos, (b) textural diagram and (c) XRD patterns of a highly oriented graphite block after heat treatment at 2800℃

图3 高定向石墨块2800℃石墨化样品不同面的SEM照片

Fig. 3 Typical SEM images of a graphite block after heat treatment at 2800℃ showing various planes (a-A, b-B, c-C)

图4 高定向石墨块2800℃石墨化样品C面的偏光照片

Fig. 4 Typical PLM micrographs of graphite block after heat treatment at 2800℃ showing the cross-section of side C

表1 不同沥青粘结剂所制石墨块的物理性质

Table 1 Physical properties of graphite blocks made with different pitch binders

Pitch binder	ρ/ (g·cm^-3)	σ/ (μΩ·m)	α/ (mm²·s^-1)	λ/ (W·m^-1·K^-1)
WG	1.76	2.02	294.01	388.1
NP	1.78	1.62	309.74	413.5
MP	1.83	1.27	385.66	529.3
SC	1.78	1.31	363.01	484.6
AR	1.91	1.45	395.52	551.6

表2 不同沥青粘结剂的基本物理性质

Table 2 Basic physical properties of different pitch binders

Pitch binder	Softening point/℃	Ash content/%	Volatile content/%	Carbon yield/%	TI/%	QI/%
WG	110	0.12	48.65	50.56	31.5	11.2
NP	82	0.004	55.31	44.65	1.3	1.0
MP	275	0.02	21.67	78.24	69.4	42.5
SC	280	0.03	19.52	80.25	67.8	20.6
AR	266	0.001	22.03	77.95	66.9	50.8

表3 不同沥青粘结剂2800℃石墨化后的微晶参数

Table 3 Microcrystal parameters of the different pitch binder-derived graphite particles after 2800℃ graphitization treatment

Pitch binder	d₀₀₂	L_a/ nm	L_c/ nm	g/ %
WG	0.3367	73.1	20.4	84.88
NP	0.3365	86.4	24.5	87.21
MP	0.3357	316.7	25.0	96.51
SC	0.3366	79.2	22.7	86.05
AR	0.3356	475	26.5	97.67

图5 不同沥青粘结剂2800℃石墨化后样品的偏光显微照片

Fig. 5 Typical PLM micrographs of different pitch binder-derived graphite particles after heat treatment at 2800℃ a-WG; b-NP; c-MP; d-SC; e-AR

图6 不同沥青用量样品2800℃石墨化后的室温热导率和热扩散系数

Fig. 6 Room-temperature thermal conductivity and thermal diffusivity of graphite blocks heat treated at 2800℃ versus initial weight fraction of mesophase pitch

图7 石墨块内部有序堆积的天然鳞片石墨和沥青粘结剂衍生炭的理想结构

Fig. 7 Ideal structure of stacked natural graphite flakes and pitch binder derived carbon particles in a graphite block

表4 不同粒度鳞片石墨所制石墨块样品室温面向热扩散系数与热导率

Table 4 Room-temperature thermal diffusivity and thermal conductivity of graphite blocks prepared with different particle- sized graphite flakes

Thermal property	Particle sizes of graphite flakes/ mesh
Thermal property	80-40	40-32	+32	+20
α/(mm²·s^-1)	343.8	360.8	395.5	366.1
λ/(W·m^-1·K^-1)	484.7	514.2	551.6	510.7

表5 热压成型温度对所得石墨块物理性质的影响

Table 5 Influence of hot-pressing temperature on the physical properties of graphite blocks

Hot-pressing temperature/℃	ρ/ (g·cm^-3)	α/(mm²·s^-1)	λ/(W·m^-1·K^-1)
300	1.66	331.36	412.5
500	1.91	395.52	551.6
650	1.95	415.13	607.1

图8 不同温度热处理石墨块的室温面内热导率

Fig. 8 Room-temperature thermal conductivity of graphite blocks versus heat treatment temperature

表6 掺杂金属前后石墨块的物理性质

Table 6 Physical properties of 2800℃ treated graphite blocks before and after doping

Dopants	ρ/(g·cm^-3)	σ/(μΩ·m)	α/(mm²·s^-1)	λ/(W·m^-1·K^-1)
Undoped	1.91	1.45	395.52	551.6
5wt% Si	1.79	1.90	307.21	412.4
5wt% Ti	1.89	1.52	296.60	420.4
3wt%Si+ 5wt%Ti	1.65	2.25	229.20	283.6

图9 石墨块样品和纯铜的高温热学性质

Fig. 9 Thermophysical properties of graphite blocks and copper versus testing temperatures under non-oxygen atmosphere

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高定向石墨块的控制制备及其导热性能影响因素研究

Controlled Preparation and Thermal Conductivity of Highly Oriented Graphite Blocks

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