Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

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2 Carbon Nanotube–Metal Nanocomposites 2.1 Overview Metal-matrix composites (MMCs) reinforced with ceramic offer the attractive combination of strength, stiffness, wear- and creep-resistant characteristics over monolithic alloys. The composites were initially developed for military and space applications. However, recent demand for materials with specified functional properties has led to their broad applications in ground transportation, automotive, chemical, electronic and recreational industries. Ceramic reinforcements introduced into metal matrices could be continuous fibers, discontinuous short fibers, whiskers or particulates. Continuous ceramic fiber-reinforced MMCs generally possess higher mechanical strength and stiffness, but the high cost of fibers and complicated processing methods make them uneconomical for most industrial applications. In this regard, particulate-reinforced MMCs have received increasingly attention because of their ease of fabrication, lower cost and near-isotropic properties [1]. Table 2.1 lists representative reinforcement materials for MMCs. In addition to continuous ceramic fiber reinforcement, carbon fibers (CF) can also be used to reinforce metals to form composites with high specific strength and stiffness, low coefficient of thermal expansion, high thermal and electrical conductivity. Carbon fibers are mainly produced from polyacrylonitrile (PAN), and several processing steps are needed to form CFs from this polymeric precursor. These include stabilization, carbonization and graphitization. In the process, PAN precursor solution is initially spun into fibers in which polymer molecular chains align with the fiber direction. These fibers are oxidized at 220 C under tension, resulting in the fracture of hydrogen bonds and rearrangement of polar nitrile (CN) group into a thermally stable ladder bonding. The stabilized PAN fibers are then pyrolyzed at 1000–1500 C in an inert atmosphere to form a carbon ring structure. Carbonized fibers with 85–99% carbon content exhibit high tensile strength, low modulus, and very low strain to failure. The graphitization stage is an optional treatment to obtain fibers with high modulus, low tensile strength and extremely low fracture strain. In the process, carbonized fibers are further heated at or above 2000 C in an inert atmosphere to produce highly oriented graphite layers with carbon content more j43
44j 2 Carbon Nanotube–Metal Nanocomposites Table 2.1 Typical reinforcement materials for MMCs. Continuous Fiber C, B, SiC, Al2O3, Si3N4 Short fiber SiC, Al2O3 Whisker TiB, SiC, Si3N4, Al2O3, SiO2 Particulate SiC, TiC, B 4C, Al 2O 3,TiB 2,Si 3N 4, AlN than 99%. The physical and mechanical properties of CFs prepared from a PAN precursor are listed in Table 2.2 [2], which shows that commercial grade CFs use a lower cost, modified textile-type PAN. Three different grades of fibers for the aerospace category are derived from different combinations of mechanical stretching, heat treatment and precursor spinning. Carbon fibers can also be prepared from pitch through spinnerets and subsequent heat treatment somewhat similar to those of PAN-based fibers. The pitch Sources include petroleum, coal tar and asphalt. It is noted that the large crystallite size and better orientation of pitch-based fibers give rise to higher modulus, thermal conductivity and lower thermal expansion when compared with PAN-based fibers [3]. Such MMCs are generally fabricated by powder metallurgy (PM) and liquid metal routes. The PM route is mainly used for making discontinuously reinforced MMCs with a near net shape capability The process involves initial mixing of metal powders and ceramic particulates, followed by cold pressing and sintering, or hot pressing/hot Table 2.2 Properties of PAN-based carbon fibers. Property Commercial, standard modulus Standard modulus Aerospace Intermediate modulus High modulus Tensile modulus/GPa 228 220–241 290–297 345–448 Tensile strength/MPa 380 3450–4830 3450–6200 3450–5520 Elongation at break, % 1.6 1.5–2.2 1.3–2.0 0.7–1.0 Electrical resistivity/mO cm 1650 1650 1450 900 Thermal conductivity/W m –1 K –1 20 20 20 50–80 Coefficient of thermal expansion, axial direction, 10 6 K 0.4 0.4 0.55 0.75 Density, g cm –3 1.8 1.8 1.8 1.9 Carbon content, % 95 95 95 þ99 Filament diameter, mm 6–8 6–8 5–6 5–8 Manufacturers Zoltek, Fortafil, SGL Reprinted from [2]. Copyright Ó (2001) ASM International. BPAmoco, Hexcel, Mitsubishi Rayon, Toho, Toray, Tenax, Soficar, Formosa
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Sie Chin Tjong Carbon Nanotube Rein
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Sie Chin Tjong Carbon Nanotube Rein
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Contents Preface IX List of Abbrevi
Page 8 and 9: 5 Carbon Nanotube-Ceramic Nanocompo
Page 10: Preface Carbon nanotubes are nanost
Page 13 and 14: XII List of Abbreviations HIP hot i
Page 16 and 17: 1 Introduction 1.1 Background Compo
Page 18 and 19: Figure 1.2 Transmission electron mi
Page 20 and 21: 1.3 Synthesis of Carbon Nanotubes 1
Page 22 and 23: MWNTs can be as high as 70% of the
Page 24 and 25: Figure 1.7 In situ TEM images recor
Page 26 and 27: 1.3 Synthesis of Carbon Nanotubesj1
Page 28 and 29: show TEM images of MWNTs synthesize
Page 30 and 31: Since then, large efforts have been
Page 32 and 33: 1.3.4 Patent Processes Carbon nanot
Page 34 and 35: 1.4 Purification of Carbon Nanotube
Page 36 and 37: Table 1.3 Patent processes for the
Page 38 and 39: Figure 1.13 Schematic illustration
Page 40 and 41: 1.5 Mechanical Properties of Carbon
Page 42 and 43: Figure 1.14 Carbon nanotubes in hig
Page 44 and 45: Figure 1.15 In situ tensile deforma
Page 46 and 47: Table 1.7 Theoretical and experimen
Page 48 and 49: Nomenclature ~a 1 , ~a 2 Unit vecto
Page 50 and 51: carbon nanotubes. Physical Review L
Page 52 and 53: 70 Jang, I., Uh, H.S., Cho, H.J., L
Page 54 and 55: 108 Shelimov, K.B., Esenaliev, R.O.
Page 56 and 57: Bonnamy, S., Beguin, F., Burnham, N
Page 60 and 61: isostatic pressing. In certain case
Page 62 and 63: This implies the absence of effecti
Page 64 and 65: coating material, the plasma gun an
Page 66 and 67: Table 2.4 Changes in the size and v
Page 68 and 69: Figure 2.6 (a) Low and (b) high mag
Page 70 and 71: Figure 2.8 SEM micrographs showing
Page 72 and 73: Figure 2.11 Bright field TEM microg
Page 74 and 75: Figure 2.13 TEM image of bulk Al/5
Page 76 and 77: 2.5 Magnesium-Based Nanocomposites
Page 78 and 79: limited improvement in ultimate ten
Page 80 and 81: Figure 2.18 SEM micrographs of the
Page 82 and 83: Figure 2.19 (a) Low and (b) high ma
Page 84 and 85: Figure 2.22 SEM micrographs of (a)
Page 86 and 87: Figure 2.25 (a) TEM micrograph show
Page 88 and 89: 2.8 Transition Metal-Based Nanocomp
Page 90 and 91: Figure 2.27 TEM image of electrodep
Page 92 and 93: Figure 2.29 SEM micrographs of (a)
Page 94 and 95: Figure 2.31 Schematic representatio
Page 96 and 97: einforcement content SiCp/Al compos
Page 98 and 99: Materials Science Forum, 534-536 (P
Page 100 and 101: composite. Materials Science and En
Page 102: 111 Cha, S.I., Kim, K.T., Arshad, S
Page 105 and 106: 90j 3 Physical Properties of Carbon
Page 107 and 108: 92j 3 Physical Properties of Carbon
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94j 3 Physical Properties of Carbon
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100j 3 Physical Properties of Carbo
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104j 4 Mechanical Characteristics o
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132j 5 Carbon Nanotube-Ceramic Nano
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186j 7 Mechanical Properties of Car
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Table 8.1 Patent processes for maki
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218j 8 Conclusions development of c
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220j 8 Conclusions Figure 8.2 TEM m
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222j 8 Conclusions increase in Vick
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224j 8 Conclusions References 1 Cha
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226j 8 Conclusions nano-matrix. Scr
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228j Index l laser ablation 7 load
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