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Characterization of metal-carbon nanotube composites17eueuMicroscopyandAnalysis | July/August 2017matrix. Fig.9 (b) shows the Vickers microhardness of various Cu-MWCNT composites. The hardness values of Cu-MWCNT composites increase gradually with the increase in the amount of carbon nanotubes in the Cu-MWCNT composites. Carbon nanotubes can withstand higher loads than the Cu matrix and hence there is a substantial increase in the hardness values. This is possibly due to the interfacial bonding between the MWCNTs and the Cu matrix, which is aided by the functionalization of MWCNTs. The highest hardness value was 1.44 GPa achieved for Cu-5 vol. % MWCNTs composites. The hardness enhancement is an indication of good physical bonding at Cu-MWCNTs interface.MWCNT reinforced Cu-based metal matrix composites were fabricated by powder metallurgy method. The dispersion of CNTs in the Cu matrix plays important role in enhancing the wear resistance of the Cu-MWCNTs composites. The wear characteristics for Cu-MWCNTs composites shown in Figure 10 (a) indicate that the wear resistance of the Cu-MWCNTs composites increases with increasing volume fraction of the MWCNTs in the composite.The MWCNTs act as a lubricating carbon film. The low coefficient of friction of the MWCNTs leads to higher wear resistance of the Cu-MWCNTs composite. With the addition of MWCNTs there is reduction in direct contact between the Cu matrix and the indenter. Figs.10 (b-d) show the FESEM images of the wear tracks of Cu-1, 2 and 5 vol. % MWCNTs composites. It can be seen that the width of the wear track reduces with the increase in volume fraction of MWCNTs in the Cu-MWCNTs composite.SUMMARY AND CONCLUSIONSThe relative density of the Cu-MWCNTs composites increase with the increase in the volume fraction of carbon nanotubes in the Cu matrix. However, the Cu-MWCNTs composites do not show significant increase in densification after addition of 2 vol. % of MWCNTs in the Cu matrix.The hardness of Cu-MWCNTs composites increases gradually with the increase in the amount of carbon nanotubes in the Cu-MWCNTs composites. Cu-5 vol. % MWCNTs composite showed highest hardness of 1.44 GPa. Addition of MWCNTs to the Cu matrix improved the wear resistance of the Cu-MWCNTs composites. An increase in wear resistance of the Cu-MWCNTs composites was seen with the addition of upto 5 vol. % of MWCNTs.REFERENCES1 Hull, D. and T.W. Clyne, An Introduction to Composite Materials. 1996: Cambridge University Press.2. Chawla, K.K., Metal Matrix Composites, in Materials Science and Technology. 2006, Wiley-VCH Verlag GmbH & Co. KGaA.3. Chawla, K.K., Composite Materials: Science and Engineering. 1998: Springer.4. Harris, B. and I.o. Materials, Engineering Composite Materials. 1999: IOM.5. Matthews, F.L. and R.D. Rawlings, Composite Materials: Engineering and Science. 1999: CRC Press.6. Miracle, D.B., Metal matrix composites – From science to technological significance. Composites Science and Technology, 2005. 65(15–16): p. 2526-2540.7. Seong-Min, C. and A. Hideo, Nanocomposites—a new material design concept. Science and Technology of Advanced Materials, 2005. 6(1): p. 2.8. Schubert, T., et al., Interfacial design of Cu-based composites prepared by powder metallurgy for heat sink applications. Materials Science and Engineering: A, 2008. 475(1–2): p. 39-44.9. Iijima, S., Carbon nanotubes: past, present, and future. Physica B: Condensed Matter, 2002. 323(1–4): p. 1-5.10. Iijima, S., P.M. Ajayan, and T. Ichihashi, Growth model for carbon nanotubes. Physical Review Letters, 1992. 69(21): p. 3100-3103.11. Iijima, S., et al., Structural flexibility of carbon nanotubes. The Journal of Chemical Physics, 1996. 104(5): p. 2089-2092.12. Iijima, S. and T. Ichihashi, Single-shell carbon nanotubes of 1-nm diameter. Nature, 1993. 363(6430): p. 603-605.13. Fu, H., et al., Synthesis and mechanical properties of Cu-based bulk metallic glass composites containing in-situ TiC particles. Scripta Materialia, 2005. 52(7): p. 669-673.14. Kim, K.T., S.I. Cha, and S.H. Hong, Hardness and wear resistance of carbon nanotube reinforced Cu matrix nanocomposites. Materials Science and Engineering: A, 2007. 449–451: p. 46-50.15. Futaba, D.N., et al., Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes. Nat Mater, 2006. 5(12): p. 987-994.16. Li, H., et al., Strong and ductile nanostructured Cu-carbon nanotube composite. Applied Physics FIGure 9 (a) Relative Density plot of various sintered Cu-MWCNTs composite; (b) Vickers hardness plot of various Cu-MWCNTs composite.bA

Characterization of metal-carbon nanotube composites18euJuly/August 2017 | MicroscopyandAnalysisLetters, 2009. 95(7): p. 071907.17. Li, H., et al., Processing and characterization of nanostructured Cu-carbon nanotube composites. Materials Science and Engineering: A, 2009. 523(1–2): p. 60-64.18. Yang, W., Y. Feng, and W. Chu, Catalytic Chemical Vapor Deposition of Methane to Carbon Nanotubes: Copper Promoted Effect of Ni/MgO Catalysts. Journal of Nanotechnology, 2014. 2014: p. 5.19. Che, G., et al., Chemical Vapor Deposition Based Synthesis of Carbon Nanotubes and Nanofibers Using a Template Method. Chemistry of Materials, 1998. 10(1): p. 260-267.20. Kong, J., A.M. Cassell, and H. Dai, Chemical vapor deposition of methane for single-walled carbon nanotubes. Chemical Physics Letters, 1998. 292(4–6): p. 567-574.21. Stobinski, L., et al., Multiwall carbon nanotubes purification and oxidation by nitric acid studied by the FTIR and electron spectroscopy methods. Journal of Alloys and Compounds, 2010. 501(1): p. 77-84.22. Lal, M., et al., An alternative improved method for the homogeneous dispersion of CNTs in Cu matrix for the fabrication of Cu/CNTs composites. Applied Nanoscience, 2013. 3(1): p. 29-35.©John Wiley & Sons Ltd. 2017biographyHarshpreet Singh started his career by obtaining a Bachelor's degree in field of Mechanical Engineering. He completed his Master of Technology (by Research) in the field of Composite Materials and received a TEQIP Scholarship during his Master's studies. He came to New Zealand in 2015, after winning University of Auckland Doctoral Scholarship to pursue his PhD at University of Auckland, New Zealand and joined CACM. At the University of Auckland, his work focuses on the development of Metal matrix composites for automotive and aerospace applications. abstractMetal matrix composites (MMCs) combine the ductility of metal and the toughness of the reinforcement which makes it an excellent candidate material for advanced engineering applications. The unique features of MMCs like high strength to weight ratio and high stiffness per unit density results in improvement of the service performance. Cu has been extensively used as a matrix due to its superior thermal and electrical properties. In the present study multiwalled carbon nanotubes (MWCNTs) were developed by using low pressure chemical vapour deposition (LPCVD) process. The microstructure of the composites was analysed using an optical microscope, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), energy dispersive x-ray spectroscopy (EDX) and high resolution transmission electron microscope (HRTEM). X-ray diffraction of the various composites was done in order to determine the different phases in the sintered composites. Wear properties of the various composites was analysed using a ball-on-plate tribometer.acknowledgements I would like to thank the staff in the SEM and XRD laboratories at the National Institute of Technology-Rourkela, India. We thank everyone involved at the National Institute of Technology- Rourkela for their useful feedback and help, and the Metallurgical and Material Engineering Department of the Indian Institute of Technology Kharagpur for carrying out HRTEM. Corresponding author details Harshpreet Singh, Department of Chemical and Materials Engineering, University of Auckland, New Zealand, 314-390 Khyber Pass Road, Newmarket 1023 Auckland, NZMobile: +64-0223917811Email: hsin287@aucklanduni.ac.nzMicroscopy and Analysis 31(4): 14-18 (EU), August 2017FIGure 10 (a) Wear Characteristic of Cu- MWCNT composites and FESEM images of the wear track of (b) Cu- 1 vol.% MWCNT (c) Cu- 2 vol.% MWCNT and (d) Cu- 5 vol.% MWCNTs composite BADC