|
Carbon nanotube metal matrix composites (CNT-MMC) are an emerging class of new materials that are being developed to take advantage of the high tensile strength and electrical conductivity of carbon nanotube materials. Critical to the realization of CNT-MMC possessing optimal properties in these areas are the development of synthetic techniques that are (a) economically producible, (b) provide for a homogeneous dispersion of nanotubes in the metallic matrix, and (c) lead to strong interfacial adhesion between the metallic matrix and the carbon nanotubes. Since the development of CNT-MMC is still in the research phase, the current focus is primarily on improving these latter two areas. ==Carbon nanotubes reinforced metal matrix composites production methods== According to the new production systems, Carbon nanotubes reinforced metal matrix composites (CNT-MMC) may produce several different methods. These production methods are: 〔S. R. Bakshi, D. Lahiri, and A. Argawal, ''Carbon nanotube reinforced metal matrix composites - A Review'', International Materials Reviews, vol. 55, p.41 (2010), http://web.eng.fiu.edu/agarwala/PDF/2010/12.pdf〕 〔Arvind Agarwal, Srinivasa Rao Bakshi,Debrupa Lahiri, ''Carbon nanotubes reinforced metal matrix composites'', CRC Press, p. (4-5-6-7-8), http://www.crcpress.com〕 Powder metallurgy Route Technics #Conventional Sintering #Hot Pressing 〔S. Suarez, F. Lasserre, O. Prat & F. Mücklich. "Processing and interfacial reaction evaluation in MWNT/Ni bulk composites" Physica Status Solidi A (2014). 〕 #Spark Plasma Sintering #Deformation Processing #Hot Extrusion 〔Mortazavi Majid, G. H. Majzoobi, Golikand A. Noozad, A. Reihani, S. Z. Mortazavi, M. S. Gorji, ''Fabrication and mechanical properties of MWCNTs-reinforced aluminum composites by hot extrusion'' ,Rare Metals, Volume 31, Issue 4, pp 372-378 (2012), http://link.springer.com/article/10.1007%2Fs12598-012-0523-6?LI=true〕 #Semi-solid Powder Processing 〔Yufeng Wu, Gap Yong Kim, ''Carbon nanotube reinforced aluminum composite fabricated by semi-solid powder processing'' ,Journal of Materials Processing Technology, Volume 211, Issue 8, August 2011, Pages 1341–1347, http://www.sciencedirect.com/science/article/pii/S0924013611000707〕 Electrochemical Routes(for non-structural applications) #Electro-deposition #Electroless Deposition Thermal spraying #Plasma Spraying #HVOF Spraying #Cold Kinetic Spraying Melt Processing #Casting #Melt Infiltration Novel Techniques #Molecular Level Mixing #Sputtering #Sandwich Processing #Torsion/Friction Processing #CVD and PVD (Physical vapor deposition) #Nanoscale Dispersion #Pulsed laser deposition Indigenous techniques #Such as molecular level mixing (in which CNTs are dispersed into a metal-salt bath, forming a metal-CNT precursor). ;Powder metallurgy techniques Sintering is one of the oldest method in production technics and used to produce density-controlled materials and components from metal or ceramic powders by applying thermal energy. 〔Suk-Joong, L. Kang ''Sintering -Densification, Grain Growth and Microstructure'', Elsevier Butterworth-Heinemann, 2005, ISBN 0-7506-6385-5, p.3〕 Synthesis and sintering of nanocrystalline ceramic powders have attracted much attention due to their promising properties.〔V.V. Srdic, M. Winterer, and H. Hahn, Sintering Behavior of Nanocrystalline Zirconia Doped with Alumina Prepared by Chemical Vapor Synthesis, ''J. Am. Ceram. Soc.'', 83, 1853-60 (2000).〕 The high active surface area of nanopowders results in lowering sintering temperature relative to coarser powders. Although low temperature sintering suppresses the grain growth, high density of interfaces and grain boundaries in nanocrystalline powders leads to accelerated grain growth during sintering. 〔J. H. Driver, Stability of Nanostructured Metals and Alloys, Scripta Materialia, 51, 819-823 (2004).〕 #Conventional Sintering is the simplest method for producing CNT metal matrix composite compacts.The CNTs and metal powders are mixed by a process of mechanical alloying/blending and then are compressed to form a green compact, which is then sintered to get the final product. Metallic compacts are subject to oxidation as compared to ceramics and hence the sintering has to be done in an inert atmosphere or under vacuum.〔Arvind Agarwal, Srinivasa Rao Bakshi, Debrupa Lahiri, ''Carbon nanotubes reinforced metal matrix composites '', CRC Press, p.20, http://www.crcpress.com,〕 One major drawback of this processing route is the inability to tailor the CNT distribution within the metallic matrix. #Microwave sintering is one of them and fundamentally different from conventional sintering.In microwave sintering process,the material is heated internally and volumetrically unlike in a conventional process where heat originates from an external heating source.Sintering cycle time for microwave sintering is much shorter as compared with the conventional sintering cycle.〔A. Mondal, A. Upadhaya, D. Agrawal ''Microwave and conventional sintering of premixed and prealloyed tungsten heavy alloys'', 2008 MS&T08, p.2502 (2008)〕 #Spark plasma sintering is a quite new technique which takes only a few minutes to complete a sintering process compared to conventional sintering which may take hours or even days for the same.High sintering rate is possible in SPS since high heating rates can be easily attained due to internal heating of the sample as oppsed to external heating seen in case of conventional sintering.For conventional sintering usually a green compact needs to be prepared externally using a suitable die and hydraulic machine for applying the necessary pressure.In SPS the powder is directly fed into the graphite dies and the die is enclosed with suitable punches.All types of materials, even those difficult to densify can be easily sintered in SPS.Due to advantage of high heating rate and less holding time, SPS can restrict the unwanted sintering reactions in highly reactive systems as opposed to conventional sintering and hence formation of undesirable product phases can be avoided.〔Materials and Metallurgical Engineering Indian Institute of Technology Kanpur, ''Spark Plasma Sintering'',http://www.iitk.ac.in/biomaterialslab/Spark%20Plasma%20Sintering.pdf, p.2〕 # Semi-solid Powder Processing (SPP) is a unique method that fabricates composites materials with powder mixtures in the semi-solid states. Starting with metal-CNT powder mixture, the metal powder is heated to the semi-solid state, and pressure is applied to form the metal matrix composites. This method features many advantages such as simple and fast process and flexible property tailoring.〔Yufeng Wu, Gap Yong Kim, Alan Russell, ''Effects of mechanical alloying on an Al6061–CNT composite fabricated by semi-solid powder processing'' ,Materials Science and Engineering: A, Volume 538, 15 March 2012, Pages 164–172, http://www.sciencedirect.com/science/article/pii/S0921509312000470〕 ;Carbon nanotube dispersing and CNT breakage during mixing One common method to disperse the CNT into the metal matrix is mechanical alloying. However, many researchers reported the length reduction and damage of CNTs during mechanical alloying process.〔Yufeng Wu, Gap Yong Kim, Alan Russell, ''Mechanical alloying of carbon nanotube and Al6061 powder for metal matrix composites'' ,Materials Science and Engineering: A, Volume 532, 15 January 2012, Pages 558–566, http://www.sciencedirect.com/science/article/pii/S0921509311012433〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Carbon nanotube metal matrix composites」の詳細全文を読む スポンサード リンク
|