INTERNATIONAL JOURNAL of ACADEMIC RESEARCH
Vol. 5. No. 2. March, 2013
U. Abdullah, M.A. Maleque, I.I. Yaacob, M.Y. Ali. Characterization of carbon nanotube aluminium nano composite- effect of ball milling time on particle size. International Journal of Academic Research Part A; 2013; 5(2), 91-93. DOI: 10.7813/2075-4124.2013/5-2/A.13
CHARACTERIZATION OF CARBON NANOTUBE ALUMINIUM NANO COMPOSITE- EFFECT OF BALL MILLING TIME ON PARTICLE SIZE U. Abdullah, M. A. Maleque, I.I. Yaacob, M.Y. Ali Department of Manufacturing and Materials Engineering, Kulliyyah of Engineering, International Islamic University, P.O.Box 10, 50728 Kuala Lumpur (MALAYSIA) E-mails:
[email protected],
[email protected],
[email protected], mmyali2iium.edu.my DOI: 10.7813/2075-4124.2013/5-2/A.13 ABSTRACT The discoveries of carbon nano tube change the direction of the research in the field of fibrous materials and are attracting much interest as reinforcement to aluminium matrix for carbon nano tubes (CNTs) aluminium (Al) matrix nano-composite. This is due to unique properties such as high strength, elastic modulus, flexibility and high aspect ratios. However, the quality of the dispersion is the major concerning factor which determines the homogeneity of the enhanced mechanical and tribological properties of the composite. This work study the particle size of aluminium powder in the CNTs-Al nano-composite prepared with different weight percentage of CNT in aluminium matrix using powder metallurgy route under high energy planetary ball milling operations at different time intervals. The experimental results showed homogeneous dispersion of CNTs in aluminium matrix at 250 rpm and the aluminium particle size increased from 78 µm up to 156 µm after just 3 hrs of milling. The preliminary mixing of CNTs and aluminium powder in a tube via manual shaking and the speed used could be the main contributing factor in achieving uniform dispersion of CNT in aluminium matrix within short time. Key words: Ball milling time, Aluminium powder, Carbon nano tube, nano-composite 1. INTRODUCTION Nano-composite materials are multiphase materials obtained through the artificial combination of different materials in order to attain properties that the individual components by themselves cannot attain. Research in the field of carbon was revolutionized by the discovery of carbon nanotubes (CNTs) by Iijima in 1991). Experiments and simulations showed that CNTs have extraordinary mechanical properties over carbon fibers, e.g. stiffness up to 1000 GPa, strength of the order of 100 GPa [2], and thermal conductivity of up to 6000 W mK. Carbon nanotube reinforced metal matrix composites (CNT-MMC) are prepared using different type of processing techniques. Powder metallurgy (PM) is the most popular and widely used route by the researchers to synthesize CNT-MMC materials. Carbon nanotube reinforced aluminium (CNT-Al) composites are mainly produced using powder metallurgy method. Ball milling is the easier and cheaper means of synthesization of composite materials using powder metallurgy route. It is believed that graphitic type of carbon fiber enhance the thermal conductivity can also be enhanced significantly. Many researchers reported that a relatively small amount of nanoscale reinforcement can have a notable effect on the macroscale properties of the composite due to the large amount of reinforcement surface area (Noguchi et al., 2004, Morsi and Esawi, 2007; Esawi et al., 2009, Abdullahi et al., 2012). For example, reinforcement of carbon nanotubes in to the metal matrix enhanced the thermal conductivity and electrical properties, heat resistance or mechanical properties such as stiffness, strength and can notably reduce the density of the material. These enhance properties can only achieved when there is uniform dispersion of the CNT in to the Al matrix and the major problems in the manufacture of MWCNT-Al nano-composite is the clustering of CNTs in the Al matrix. This is due to the complex entanglements of long and smooth CNTs and resulting agglomeration due to strong van der Waals forces of attraction between them. Furthermore, the weak interfacial bonding due to the poor wettability of carbon nanotube with Al has been an obstacle to impart effective load transfer between the MWCNT and the Al matrix. In addition, the formation of aluminium carbide (Al4C3) phase in the fabrication process complicates the strengthening mechanism of the composite [3]. Recently, Kwon et al. [7] claim in their MWCNT-Al composites study that Al4C3 was formed and stabilized on the surface of the tip of CNT and also helped in the transfer of stress from Al matrix to the CNTs. But, their experimental study was restricted to 0.5 vol % of MWCNT. More recently, Liao et al. [8] claim in their CNT-Al nano-composite study that, a significant enhancement in the composite properties at initial loadings 0.5 wt % of MWCNTs when compared to Al samples without much increase in cost. There work is restricted to the MWCNT weight fraction of 2.0% and they did not study other percentage close to 2.0 wt% and investigate the properties. Therefore, in this paper, the effect of ball milling parameters on three different weight percentage of carbon nano tube and the aluminium powder particle is studied. The FESEM morphology of CNT-Al nano-composite is also presented.
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INTERNATIONAL JOURNAL of ACADEMIC RESEARCH
Vol. 5. No. 2. March, 2013
2. MATERIALS AND METHOD Pure Al (99.7%), with particle size of 78 µm which has nearly spherical shape with some satellite subparticles was used as a matrix material. The image of the aluminum powder obtained using scanning electron microscopy (SEM) is showed in Fig.1a. The multi walled carbon nano tubes (MWCNTs) with a nominal diameter of 2 -1 10 nm, length of 5-15 µm, and surface area of 40-300 m g was used as a reinforcement. The image of the MWCNTs obtained through field emission scanning electron microscopy (FESEM) is shown in Fig. 1b. Three compositions such as 1.5, 2 and 2.5 wt% CNT with Al were studied in this investigation. Each composition was place in a tube together with a stainless steel ball of 10 mm diameter to make the ratio of ball-to-powder ratio of 5:1 for preliminary mixing via manual shaking for about 10-15 minutes. The preliminary mixture was then placed in 250 mL mixing jar containing stainless steel milling balls of 10 mm diameter, the initial ball-to-powder weight ratio (BPR) is 10:1 and ethanol was added as a process control agent (PCA). The jar was filled with argon gas and the ball mill operations started using planetary mill (FRITSCH pulverisette 5 05.5000/00409) at fixed speed of 250 rpm for milling time of up to 5hours. Sample was extracted from each batch at a regular interval of 1 h for characterization using a FESEM in order to investigate the dispersion of the CNTs in the Al matrix. (a)
(b
Result and discussion
Fig.1. Image of the as-received aluminium powder and CNT
Fig. 2. Ball milling set up
Fig. 3. FESEM micrographs showing the effect of milling time and speed on particle shape and size morphology change with 1.5, 2 and 2.5 wt% CNT-Al nano-composites
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3. RESULT AND DISCUSSION The FESEM micrographs are presented in Fig. 3 which shows that, for both CNT contents used aluminium particles changes to flakes like structure even from the initial first hour which later welded to rough flat circular and became round but smooth as milling continued with minimal CNTs cluster. The size also tends to increase up to the maximum of 156 µm after 5 hr of milling and it continued to increase in size as the milling time extended for both CNTs contents. This transformation of the particle size and morphology is as a result of the impact of the balls. In terms of CNT dispersion, it is assumed that, the dispersion was uniform in the aluminium matrix because no cluster observed. Morsi and Esawi (2007), study the effect of mechanical alloying time and carbon nano tube (CNT) content on the evolution of aluminium (Al)-CNT composite powders for 48 hrs of milling time and achieved better homogenization of CNT in aluminium with the round smooth only for 2 wt% CNT. In our investigation, no much difference with the transformation occurred with time variations for both CNT contents and the dispersion or homogenization of CNT was achieved within short time of 250 rpm milling speed. It can be postulated that slight CNTs percentage variations, the use of PCA and the preliminary mixing of CNTs and aluminium powder in a tube via manual shaking could be the main contributing factor in achieving uniform dispersion of CNT in aluminium matrix after a short milling time with smooth and large particle size for 1.5, 2 and 2.5 wt% CNTs. 4. SUMMARY The results presented in this paper illustrated that ball milling is a promising technique for the homogeneous and uniform dispersion of CNT in aluminum matrix, and the ball milling parameters plays a tremendous role on the particle size and morphology. It also revealed that the use of process control agent (PCA) such as ethanol and the high milling speed can play a significant role in controlling the cluster of CNT during milling operation and preliminary mixing via hand shaking can reduce the milling time. The 1.5, 2 and 2.5 wt% CNT in CNT-Al nanocomposite has similar pattern of transformation in size and morphology due to balls impact during milling operations. ACKNOWLEDGEMENTS This work was supported by RMC, IIUM under research grand No. EDW-B-11-084-0562. REFERENCES 1. S. Iijima: Helical microtubules of graphitic carbon, Nature (London), Vol.354, (1991), p. 56-58. http://dx.doi.org/10.1038/354056a0. 2. S.R Bakshi, D. Lahiri and A. Agarwal: Carbon nanotube reinforced metal matrix composites- a review, International Materials Reviews, Vol. 55, No 1, (2010) p. 41-64. http://dx.doi.org/10.1179/ 095066009X12572530170543. 3. M.A.T. Noguchi, S. Fukazawa, S. Shimizu, J. Beppu, M. Seki, (2004) Carbon nanotube aluminium composites with uniform dispersion. Mater Trans (45):602–4. http://dx.doi.org/10.2320/matertrans. 45.602. 4. A.M.K. Esawi and M. A. El Borady: Carbon nanotube-reinforced aluminium strips. J. Comp. Sci. Technol. (2007), Vol.68, p. 486-492. 5. A.M.K. Esawi, K. Morsi, A. Sayeda, A.A. Gawada and P. Boran: Fabrication and properties of dispersed carbon nanotube– aluminum composites. J. Mater. Sci. Eng. A 508, (2009), p. 167-173. http://dx.doi.org/10.1016/j.msea.2009.01.002. 6. U. Abdullahi, M.A. Maleque, I.I Yaacob and M.Y. Ali: Effect of Ball Milling Parameters on the Synthesization of Carbon Nanotube Aluminium Nano Composite. J. Adv. Mater. Res. Vol. 626, (2013), pp 537-542. 7. H. Kwon, D. Hoon park, J.F. Silvain, and A. Kawasaki, (2010) Investigation of carbon nanotube Reinforced aluminum matrix composite materials. Composites Science and Technology, (70): pp 546–550. http://dx.doi.org/10.1016/j.compscitech.2009.11.025. 8. J. Liao, M. Tan, and I. Sridhar, (2010) Spark plasma sintered multi-wall carbon nanotube reinforced aluminum matrix composites. Materials and Design (31):S96-S100. http://dx.doi.org/10.1016/ j.matdes.2009.10.022. 9. U. Abdullahi, M.A. Maleque, I.I Yaacob and M.Y. Ali: Carbon Nano tube Reinforced Aluminium Matrix Nano-Composite: a Critical Review. Australian Journal of Basic and Applied Sciences. Vol. 6(12), (2012), pp 69-75. 10. A.S.S Mohamed, A. Esawi, and K. Morsi, (2010) Fabrication and Properties of Carbon Nanotube (CNT) –Reinforced Aluminium Composites. B.Sc. in Mechanical Engineering thesis, School of science and Engineering, American university in cairo, cairo, Egypt. 11. S. Salimi, H. Izadi and A.P Gerlich: Fabrication of an aluminum–carbon nanotube metal matrix composite by accumulative roll-bonding. J. Mater. Sci. Vol.46(2), (2011), p. 409-415. http://dx.doi.org/10.1007/s10853-010-4855-z.
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