Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

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limited improvement in ultimate tensile strength as expected. Similarly, Carreno- Morelli et al. also blended Mg/2 wt% MWNT in a Turbula mixer, followed by hot pressing and hot isostatic pressing [19]. Very little improvement in mechanical strength is found for such nanocomposites. Reducing the length of CVD grown CNTs is found to be very effective to fully incorporate and disperse CNTs into composites. The length of CVD-grown CNTs can be controlled mechanically through ultrasonication, ball milling, and high speed shearing. Very recently, Shimizu et al. used a high-speed blade cutting machine to reduce the length of CVD prepared MWNTs [63]. Damaged MWNTs with an average length of 5 mm were mixed mechanically with AZ91D magnesium alloy powders in a mill containing zirconia balls under a protective argon atmosphere. Milled composite powder mixtures were then hot pressed and extruded into rods (Figure 2.17(a)–(e)). At 1 wt% MWNTs, CNTs are distributed uniformly in magnesium powders (Figure 2.17(c)). When the filler content is increased to 5 wt%, agglomeration of MWNTs occurs (inset of Figure 2.17(d)). Figure 2.17 SEM images of (a) mechanically milled AZ91D magnesium alloy powders of 100 mm; (b) shortened CNTs with an average length of 5 mm; (c) mechanically mixed AZ91D/ 1 wt% CNT powders; (d) mechanically mixed AZ91D/5 wt% CNT powders; (e) extruded AZ91D/CNT nanocomposite rods. Reproduced with permission from [63]. Copyright Ó (2008) Elsevier. 2.5 Magnesium-Based Nanocompositesj63
64j 2 Carbon Nanotube–Metal Nanocomposites 2.5.3 Friction Stir Processing Friction stir processing (FSP) is a solid state processing method, developed on the basic principles of friction stir welding; it is an effective tool to form fine-grained microstructures in near surface region of metallic materials. In the process, a rotating pin tool is inserted to the substrate, the resulting frictional heating and the large processing strain produce microstructural refinement, densification and homogenization [64]. Mishra et al. fabricated the Al-based surface composites by dispersing SiC powders (0.7 mm) on the surface of Al 5083 Al (Al-Mg-Mn) alloy plate followed by FSP treatment [65]. They reported that SiC microparticles were well bonded and dispersed in the Al matrix of surface composite layer ranged from 50 to 200 mm. Furthermore, FSP resulted in significant grain refinement in surface layer. Recently, Morisada et al. fabricated AZ31/MWCNT surface nanocomposite by using the FSP technique [66]. MWCNTs were initially filled into a groove on the AZ31 (Mg-3Al-1Zn) alloy plate followed by the insertion of a pin into the groove. The tool was rotated at a fixed speed of 1500 rpm, but its travel speed varied from 25 to 100 mm min 1 . The dispersion of CNTs depend greatly on the travel speed of pin tool. Figure 2.18(a)–(f) show SEM micrographs of AZ31/MWCNT surface nanocomposite specimens prepared from FSP with the pin traveling at different speeds. At a high travel speed of 100 mm min 1 , entangled CNTs in the form of large clusters can be readily seen in the surface composite (Figure 2.18(b)). This is because the high travel speed cannot produce sufficient frictional heat to mix CNTs properly in the alloy (Figure 2.18(d). Large MWNT clusters tend to break up into smaller agglomerates by decreasing the travel speed of pin tool. A better distribution of MWNTs is achieved at a low speed of 25 mm min 1 (Figure 2.18(f)). Careful examination of this micrograph reveals that CNTs are still agglomerated into small clusters. Much more work is needed in future to improve the dispersion of nanotubes using FSP. 2.6 Titanium-Based Nanocomposites Titanium alloys are structural materials widely used in aerospace, chemical, biomedical and automotive industries due to their excellent mechanical properties at room temperature. However, titanium alloys exhibit low mechanical strength at high temperatures. Continuous SiC fibers and TiC particulates have been incorporated into Ti alloys to enhance their mechanical performances [67–71]. Very little information is available in the literature regarding the fabrication and microstructural behavior of Ti-based nanocomposites [72]. The difficulty in dispersing CNTs in high reactivity titanium matrix hinders the development of Ti/CNT nanocomposites. This is a big challenge for materials scientists: to produce Ti/CNT nanocomposites with desired mechanical properties using novel processing techniques.
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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
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5 Carbon Nanotube-Ceramic Nanocompo
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Preface Carbon nanotubes are nanost
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XII List of Abbreviations HIP hot i
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1 Introduction 1.1 Background Compo
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Figure 1.2 Transmission electron mi
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1.3 Synthesis of Carbon Nanotubes 1
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MWNTs can be as high as 70% of the
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Figure 1.7 In situ TEM images recor
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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 58 and 59: 2 Carbon Nanotube-Metal Nanocomposi
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 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 115 and 116: 100j 3 Physical Properties of Carbo
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132j 5 Carbon Nanotube-Ceramic Nano
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170j 6 Physical Properties of Carbo
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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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