Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

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Table 4.5 Mechanical properties of electrodeposited nanocrystalline Ni and Ni/MWNT composite. the Ni/MWNT composite deposited by the pulse-reverse method exhibits higher tensile elongation (2.4%) than that of pure Ni (1.7%). The yield strength and tensile strength of Ni/MWNT composite are 1290 and 1715 MPa, respectively. By using single-walled nanotubes, the tensile strength of Ni/SWNT composite deposited under the same condition can reach as high as 2 GPa. The high reinforcing efficiency of CNTs is attributed to good interfacial bonding and stiffer nickel metal matrix. 4.3 Comparison with Nanoparticle-Reinforced Metals Ceramic nanoparticle reinforcements can markedly increase the tensile strength and elastic modulus of metals more effectively than their microparticle counterparts. The improved mechanical properties of nanocomposites can be achieved by adding very low volume fractions of nanoparticles provided that the fillers are dispersed uniformly in the metal matrices of composites [Chap. 1, Ref. 2–Chap. 1, Ref. 4]. However, ceramic nanoparticles always agglomerate into large clusters during processing, particularly at higher filler content. Figure 4.12 shows the tensile properties of PM Al reinforced with alumina nanoparticles (25 nm) of different volume fractions; and for comparison, the tensile behavior of Al reinforced with 10 vol% SiC (10 mm) particles are also shown. Apparently, the yield and tensile strengths of PM Al/Al2O3 nanocomposites increase with increasing alumina content up to 4 vol%, but thereafter level off due to severe clustering of nanoparticles. Figure 4.13(a) and (b) show typical TEM micrographs of the Al/1vol%Al2O3 and Al/4vol%Al2O3 nanocomposites. Clustering of alumina nanoparticles occurs when the filler content reaches 4 vol%. These clusters are mainly located at the grain boundaries of the aluminum matrix. The aspect ratio of spherical nanoparticles is unity, thus the contribution from the load bearing transfer effect to the strength of composites is smaller compared with that of CNTs. In this case, Orowan stress plays a major role in strengthening composites reinforced with nanoparticles [21]. Mathematically, Orowan stress can be described by the following equation [22, 23]: t ¼ 0:84 MGb ðLm dÞ 4.3 Comparison with Nanoparticle-Reinforced Metalsj117 Materials Vickers Hardness Tensile strength (MPa) Elongation (%) Nanocrystalline Ni 572 1162 2.39 Ni/MWNT Composite 645 1475 2.09 Reproduced with permission from [Chap. 2, Ref. 100]. Copyright Ó (2008) Elsevier. ð4:17Þ
118j 4 Mechanical Characteristics of Carbon Nanotube–Metal Nanocomposites Figure 4.12 Tensile properties of Al/Al2O3 nanocomposites as a function of alumina volume fraction. The tensile properties of Al/10 vol% SiC (10 mm) microcomposite are also shown. Reproduced with permission from [Chap. 1, Ref. 4]. Copyright Ó (2004) Elsevier. where t is shear yield stress, G is shear modulus, M is Taylor factor ( 3), b is Burgers vector and Lm mean inter-particle distance given by: Lm ¼ 6Vf p 1=3 d: ð4:18Þ Apparently, the yield stress of composites can be markedly enhanced by increasing the filler volume fraction and decreasing the particle diameter. Recently, Gupta s group studied the mechanical properties of PM- and DMDprepared Mg-based composites reinforced with different ceramic nanoparticles Figure 4.13 TEM micrographs of (a) Al/1vol%Al2O3 and (b) Al/4vol%Al2O3 nanocomposites. Reproduced with permission from [Chap. 1, Ref. 4]. Copyright Ó (2004) Elsevier.
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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
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show TEM images of MWNTs synthesize
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Since then, large efforts have been
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1.3.4 Patent Processes Carbon nanot
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1.4 Purification of Carbon Nanotube
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Table 1.3 Patent processes for the
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Figure 1.13 Schematic illustration
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1.5 Mechanical Properties of Carbon
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Figure 1.14 Carbon nanotubes in hig
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Figure 1.15 In situ tensile deforma
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Table 1.7 Theoretical and experimen
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Nomenclature ~a 1 , ~a 2 Unit vecto
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carbon nanotubes. Physical Review L
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70 Jang, I., Uh, H.S., Cho, H.J., L
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108 Shelimov, K.B., Esenaliev, R.O.
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Bonnamy, S., Beguin, F., Burnham, N
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2 Carbon Nanotube-Metal Nanocomposi
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isostatic pressing. In certain case
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This implies the absence of effecti
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coating material, the plasma gun an
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Table 2.4 Changes in the size and v
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Figure 2.6 (a) Low and (b) high mag
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Figure 2.8 SEM micrographs showing
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Figure 2.11 Bright field TEM microg
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Figure 2.13 TEM image of bulk Al/5
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2.5 Magnesium-Based Nanocomposites
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limited improvement in ultimate ten
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Figure 2.18 SEM micrographs of the
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Page 84 and 85: Figure 2.22 SEM micrographs of (a)
Page 86 and 87: Figure 2.25 (a) TEM micrograph show
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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
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Page 98 and 99: Materials Science Forum, 534-536 (P
Page 100 and 101: composite. Materials Science and En
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168j 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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