碳纳米管在金属间化合物中分散过程_英文__图文

1、碳纳米管在金属间化合物中分散过程庞来学1，范润华2，邢德进1，徐 静1，张金升1(1. 山东交通学院土木工程系，济南 250023；2. 山东大学材料科学与工程学院，济南 250061摘 要：采用超声分散结合机械球磨方法制备了均匀分散的多壁碳纳米管/Fe3Al 金属间化合物复合粉体。利用透射电镜和红外吸收光谱对复合粉体的形貌和结构进行研究。透射电镜分析表明：藤状的碳纳米管缠绕着Fe 3Al 纳米颗粒，使Fe 3Al 纳米颗粒定向排列在一起。复合粉体的良好结合源于 Fe C 键的形成。这种复合粉体有望提高金属间化合物的塑性和作为添加剂应用在复合材料中。关键词：多壁碳纳米管；铁铝金属间化合物；超声

2、分散；藤状结构中图分类号：TB333 文献标志码：A 文章编号：04545648(200911193804DEVELOPMENT OF A DISPERSION PROCESS FOR CARBON NANOTUBE ININTERMETALLIC MATRIXP ANG Laixue 1，F AN Runhua2，XING Dejin1，XU Jing1，ZHANG Jinsheng1(1. Department of Civil Engineering, Shandong Jiaotong University, Jinan 250023; 2. School of Material Sc

3、ience andEngineering, Shandong University, Jinan 250061, ChinaAbstract: Homogenous mixture of multiwall carbon nanotube (MWNTs and intermetallic (Fe3Al matrix was obtained by ultrasoni-cation and ball milling. Transmission electron microscopy (TEM and Fourier transform infrared spectrophotometry (FT

4、IR were used to analyze of the state of the dispersion of MWNT. It is found that the vine-like nanotubes intertwine Fe3Al nanoparticles, which causes the Fe3Al nanoparticles to be arrayed in a line. Strong bonding of composite powder comes from the FeC bond formation. The morphology of Fe3Al nanopar

5、ticles intertwined by MWNTs is expected to enhance the plasticity of intermetallic compound, and used as reinforcing agents in composites.Key words: multi-wall carbon nanotubes; iron aluminide intermetallic compound; ultrasonication; vine structureCarbon nanotubes (CNTs have attracted worldwide atte

6、ntion since being discovered due to their unique one-dimensional structure and their remarkable electrical and mechanical properties. CNTs as well as their com-posites have wide potential application, such as in rein-forced materials, nanoscale electronic devices, hydrogen storage materials, field e

7、mission and electrochemistry.12 In particular, their formidable mechanical properties, i.e . Youngs modulus up to 1 TPa for single-walled carbon nanotubes (SWNTs and 950 GPa for multiwall carbon nanotubes (MWNTs, make CNTs a promising candidate as reinforcing elements in composites to substitute for

8、 carbon fibers. Many attempts have been made to develop advanced engineering materials with CNTs as reinforcing additives in various matrices (polymers, metals and ce-ramics, 37 but the improvement in mechanical proper-ties is not satisfactory. Chen et al. 8 fabricated nano-tube/nickel/phosphorus co

9、mposite coatings on stainless steel substrates using an electroless plating method. The coatings exhibited higher wear resistance and lower fric-tion coefficients than SiC/Ni/P and graphite/Ni/P compos-ite coatings. The nanotube/copper composites prepared by a powder metallurgy technique had improve

10、d wear rates and friction coefficients due to the presence of CNTs.8 These results suggest that the nanotube/metal composites may have potential applications in the tribological field. Fe 3Al-based iron aluminide has been of interest due to its low cost, low density, good wear resistance, and resis-

11、tance to oxidation and corrosion. These advantages have attracted considerable attention as potential candidates for many structural, electrical, thermal, and magnetic applica-tions. 9 Iron aluminides have been studied extensively收稿日期：20090316。 修改稿收到日期：20090508。 基金项目：国家自然科学基金(50772061资助项目。 第一作者：庞来学(

12、1975 ，男，博士，副教授。Received date: 20090316. Approved date: 20090508. First author: PANG Laixue (1975, male, Ph.D., associate professor. E-mail: lxpang第37卷第11期 2009年11月硅 酸 盐 学 报JOURNAL OF THE CHINESE CERAMIC SOCIETYVol. 37，No. 11November ，2009庞来学 等：碳纳米管在金属间化合物中分散过程 · 1939 ·第37卷第11期during recent

13、 years by alloying and heat treatment, but few studies have covered CNTs/Fe3Al composites.10 The addition of carbon in the composite can increase the room temperature strength, and the material exhibited good room temperature ductility, owing to solid solution strengthening by interstitial carbon, a

14、s well as precipita-tion hardening due to the presence of Fe3AlC precipi-tates. 11 CNTs tend to be agglomerated with each other owing to a strong van der Waals attractive force. There-fore, it is difficult to avoid the agglomeration of CNTs during the fabrication of CNT reinforced composites. In thi

15、s work, a simple and effective method of homogeneous wrapped Fe3Al nanoparticles with MWNTs was provided using a two-step method by the strong bonds between the MWNTs and Fe3Al nanoparticles, and MWNT-wrapped Fe 3Al nanoparticles were prepared.1 Experimental procedure1.1 Preparation of powderMWNTs w

16、ere provided and prepared by chemical synthesis by Shenzhen Nanotech Port Ltd. Co. (Shenzhen, China. The MWNTs with a purity of about 95% in mass were washed in concentrated acids, and dried at 140 for 24 h to remove water. The MWNTs were dispersed in ethanol with the aid of ultrasonic agitation. Th

17、e Fe3Al nano-powder (produced as described elsewhere12 shown in Fig.1 with a spherical shape and an average particle size of about 40 nm was added to the ethanol solution with MWNTs and ultrasonically agitated again. The re-sulting slurry was ball-milled for 24 h with alumina-balls media, and subseq

18、uently dried on a hot plate in a vacuum. The mixed powders were dried at 353 K and broken up using a mortar and pestle so as to test the results of the mixture.Fig.1 TEM photograph of Fe3Al nanoparticles1.2 Observation and analysis of mixture powder The microstructure of the mixture powder was ob-se

19、rved by a transmission electron microscope (Model JEM2100F using an accelerating voltage of 200 kV . The Fourier transform infrared (FTIR spectra of the sample inthe KBr tablet were recorded using an FTIR spectropho-tometer (Model UV3101 at a resolution of 4 cm 1.2 Results and discussion2.1 The micr

20、ograph of the powdersFigure 2(a shows the TEM micrograph of the MWNTs used in the experiment. It can be seen that the MWNTs are tangled together. Their diameters are be-tween 20 and 40 nm and their lengths are tens of microns. The aspect ratio is up to 1001 000. Most of the MWNTs are not straight, b

21、ut possess some defects and demon-strate localized kinks and bends. It is interesting to note that the vine-like carbon nanotubes in Fig.2 (b are inter-twined with Fe3Al particles (in the circle; the sidewall isFig.2 TEM micrograph of MWNTs and mixture powder硅 酸 盐 学 报 · 1940 ·2009年covered

22、by particles, which cause the Fe3Al particles to be arrayed in a line. This may be related to the following factors. First, it could be due to the Fe3Al particle nano-scale effects. Fe3Al intermetallic nanoparticles show much higher tendency to form chains as compared to pure Fe and Al nanoparticles

23、. This phenomenon was also observed in other intermetallic systems such as -Cu 5Zn 8. 13 The linear array of the Fe3Al particle forma-tion is caused by particle aggregation. The nanoparticles aggregate as little chains and stack end to end. Second, the ball milling process forms defects and holes on

24、 the surface of MWNTs and some functional groups such as carbonyl and hydroxyl ones are introduced.1415 As a result, it is possible to say that carbon nanotubes with a large accessible active surface area are obtained through the ball milling process, as well as without disrupting the basic morpholo

25、gy of the carbon nanotubes, which tend to curl, resulting in the formation of vine-like MWNT in-tertwisted Fe3Al nanoparticles. Additionally, one can see from Fig.2(c that the MWNTs are dispersed in iron alu-minide powders relatively homogenously.To account for the formation of wrapped Fe3Al parti-c

26、les with MWNTs, a potential mechanism is illustrated in Fig.3. The chain morphology of nanotube intertwined nanoparticles is expected to enhance the plasticity of in-termetallic nanoparticles and this may lead to new appli-cations as additive and reinforcing agents.Fig.3 Schematic of vine-like nanot

27、ubes on Fe3Al nanoparticles2.2 FTIR spectra of powdersIn order to find the formation mechanism of the vine- like structure of the MWNT/Fe3Al composite mixture, FTIR was used to characterize the MWNTs at different stages. Figure 4 shows the FTIR spectra of pristine MWNTs, Fe3Al and mixture of Fe3Al w

28、ith MWNTs. TheFig.4 FTIR spectra of MWNTs, Fe3Al and MWNTs/Fe3Almixturepeaks near 3 430 cm 1 correspond to the stretching vibra-tions of the absorbed molecular water. The peak around 1 632 cm 1 corresponds to the bending vibrations of the absorbed molecular water.The peaks below 1 000 cm 1 belong to

29、 the characteris-tic peaks of Fe3Al. The peak around 879 cm 1 suggests an antisymmetric FeOFe stretching vibration16 as shown in Fe3Al spectrum (2 in Fig.4.In the spectrum of the pristine MWNTs in Fig.4, the peaks at 2 924 cm 1 correspond to the stretching mode of the CH bond vibration. Another tran

30、smittance around 2 854 cm 1 corresponds to the dihydride sp 3 CH2 bond state, and it is considered that some hydrogen atoms in water molecules are preferentially adsorbed on the dan-gling bonds of amorphous carbon or nanotube edges rather than the graphite surface in the form of a tetrahedral dihydr

31、ide configuration.17 This means that after the MWNT treatment in nitric acid, functional groups such as COOH, OH are created on the surface of the carbon nanotube. The transmittance between 2 8503 300 cm 1 consistent with a CHn stretching vibration was observed and remains unchanged after mixture (t

32、he spectrum of MWNTs/Fe3Al mixture in Fig.4.In the spectrum of the MWNT/Fe3Al mixture, the peak at 1 400 cm 1 corresponding to the OH vibration of carboxylic acid disappears, and an additional peak is ob-served at 1 050 cm 1. From the disappearance of the peak of the OH vibration of carboxylic acid,

33、 we speculate that the MWNTs are anchored to the Fe3Al nanoparticles through nanoparticle surface stress by ultrasonication and ball milling. In general, the ability for transition metals to bond carbon atoms increases with the number of unfilled d -orbitals. Metals such as Al have no d -vacancies a

34、nd negligible affinity for carbon; metals with few d -vacancies such as Fe exhibit finite solubility for carbon in a certain temperature range. MWNTs/Fe3Al composites are formed naturally through some physicochemical actions such as the van der Waals force, H bonding and other bonding. For example,

35、Fe may possibly bond with carbon nano-tubes through FeC bonds, and Al atoms bond with car-bon nanotubes by physical absorption. However, the high specific surface area of MWNTs is also the basis for the formation of composites. Though the density of Fe3Al is庞来学 等：碳纳米管在金属间化合物中分散过程· 1941 ·第3

36、7卷第11期greater than that of MWNTs, the MWNT/Fe3Al compos-ites could form a homogeneous dispersion in ethanol and no Fe3Al was observed to drop from the MWNTs after 0.5 h of sonication. Thus, the interaction between the molecules of these two materials is supposed to be very strong.3 ConclusionsA faci

37、le method to synthesize MWNT/Fe3Al compos-ite powder is described. Vine-like MWNTs intertwine with nanoparticles, resulting in the formation of chain- like composites. Strong bonding of MWNTs and Fe3Al composites comes from various physicochemical actions such as the van der Waals force, H bonding a

38、nd other bonding.References:1 BAUGHMAN R H, ZAKHIDOV A, de HEER W A. Carbon nano-tubesthe route toward applications J. Science, 2002, 297: 787792. 2 CURTIN W A, SHELDON B W. CNT-reinforced ceramics and metalsJ. Mater Today, 2004, 7: 4449.3 MORISADA Y, MIYAMOTO Y, TAKAURA Y, et al. Mechanicalproperti

39、es of SiC composites incorporating SiC-coated multi-walled carbon nanotubes J. Int J Refract Met Hard Mater, 2007, 25: 322 327.4 CHOI H J, KWON G B, LEE G Y, et al. Reinforcement with carbonnanotubes in aluminum matrix composites J. Scr Mater, 2008, 59: 360363.5 SHAN Yan, GAO Lian. Synthesis and cha

40、racterization of phase con-trollable ZrO2carbon nanotube J. Nanotechnology, 2005, 16: 625 630.6 ZHAN G D, KUNTZ J D, MUKHERJEE A K, et al. Thermoelectricproperties of carbon nanotube/ceramic nanocomposites J. Scr Mater, 2006, 54: 7782.7 BANSALl N P, HURST J B, CHOI S R. Boron nitride nanotubes-reinf

41、orced glass composites J. J Am Ceram Soc, 2006, 89(1: 388 390.8 CHEN.W X, TU J P, GAN H Y, et al. Electroless preparation and tri-bological properties of NiPcarbon nanotube composite coatings un-der lubricated condition J. Surf Coat Technol, 2002, 160: 6873. 9 JIA Chengchang, HE Qing, MENG Jie, et al. Influence of mechanicalalloying time on the properties of Fe3AI intermetallics prepared by spark plasma sintering J. J Univ Sci Te