Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

More documents

Recommendations

Info

component shape [53–55, 61–63]. A stable colloid with well dispersed particles produces a dense and homogeneous powder. The interparticle colloidal forces can be manipulated by adjusting the pH or by adding a dispersant. The stability of aqueous colloidal suspension can be controlled by creating like charges of sufficient magnitude on the surfaces of ceramic particles, known as electrostatic stabilization. Alternatively, ionic polymer dispersant is added to the suspension such that polymeric chains adsorb on ceramic particle surfaces creating steric repulsion. Electrosteric stabilization that combines both ionic and polymer dispersant mechanisms is more effective for obtaining a well-dispersed suspension [64, 65]. As CNTs and alumina particles show extensive agglomeration, they must disperse independently in organic suspensions. When two sols of opposite sign are mixed, mutual coagulation takes place. Under a properly selected pH range, alumina particles adsorb onto CNT surfaces through electrostatic interaction. Recently, Sun et al. fabricated alumina-CNTnanocomposites by means of colloidal processing [61]. Carbon nanotubes were treated with ammonia gas at 600 C for 3 h, and then dispersed in cationic type polyethyleneamine (PEI) solution. The treated CNTs exhibit positive charge in a wide pH range on the basis of zeta potential measurement. Zeta potential is defined as the electrokinetic potential of particulate dispersions associated with the magnitude of electrical charge at the double layer of colloidal systems. It is commonly used to measure the magnitude of attraction or repulsion between dispersed particles [66]. Alumina nanoparticles (30 nm) were dispersed independently in anionic type poly(acrylic acid) (PAA) solution, yielding electronegative charges on particle surfaces. Sodium hydroxide was used to adjust the pH of suspension solution. The alumina suspension with PAA was dripped into the CNTsuspension containing PEI under sonication. The pH value was kept at 8 for the coating of alumina on CNTs. In another study, pristine CNTs were dispersed in anionic type sodium dodecyl sulfate (SDS) solution, forming electronegative charges on nanotube surfaces [62]. SDS is recognized as an effective dispersing agent for CNTs [67]. Figure 5.7 shows Figure 5.7 Zeta potential as a function of pH for alumina and CNTs in the presence of SDS. Reproduced with permission from [62]. Copyright Ó (2003) Elsevier. 5.4 Oxide-Based Nanocompositesj141
142j 5 Carbon Nanotube–Ceramic Nanocomposites Figure 5.8 TEM image of CNTs coated with alumina in the presence of SDS. Reproduced with permission from [62]. Copyright Ó (2003) Elsevier. zeta potential vs pH plot for pristine CNT in the presence of SDS and alumina in 1 mM NaCl solution. The pH value was adjusted to 5 for coating alumina particles on CNTs. The zeta values of alumina and SDS-treated CNTs at pH 5 are about 35 and 40 mV. A very dilute alumina suspension was added to the CNT suspension. Carbon nanotube surfaces were then coated with alumina particles due to the electrostatic attraction (Figure 5.8). Since then, other researchers have employed colloidal processing to prepare alumina-CNT nanocomposites using SDS dispersant [54, 55, 68]. Figure 5.9(a) shows SEM micrograph of hot-pressed Al2O3/MWNT nanocomposite prepared by heterocoagulation using a SDS dispersant. MWNTs are found to disperse within alumina grains and at the grain boundaries. The SEM image of the polished nanocomposite specimen subjected to ion milling is shown in Figure 5.9(b). This micrograph clearly reveals homogenous dispersion of MWNTs within the matrix of the nanocomposite. The dispersion of MWNTs within the grains and grain boundaries of the alumina matrix can be readily seen in the transmission electron microscopyTEM micrographs as shown in Figure 5.9(c) and (d). 5.4.1.2 Spark Plasma Sintering Murkerjee s group prepared Al2O3/5.7 vol% SWNT and Al2O3/10 vol% SWNT nanocomposites by blending and ball milling SWNTs with alumina nanopowders, followed by spark plasma sintering at 1150 C for 2–3 min [44]. Pure alumina and Al2O3/5.7 vol% SWNT and Al2O3/10 vol% SWNT nanocomposites can be consolidated to full density of 100% at 1150 C for 3 min (Table 5.2). The matrix grain size of the Al2O3/5.7 vol% SWNT and Al2O3/10 vol% SWNT nanocomposites is considerably smaller than that of pure alumina. Thus, SWNTs are very effective to retard the grain growth of alumina during SPS. Moreover, CNTs tend to form a network structure at grain boundaries (Figure 5.10). Generally, sintering time and temperature have a large influence on the density of resulting nanocomposites. For example, the relative density of the Al2O3/10 vol% SWNT nanocomposite drops to 95.2% by reducing the sintering time to 2 min at 1150 C. At 1100 C for 3 min, the relative density of the Al2O3/10 vol% SWNT nanocomposite reduces to 85.8%.
Page 2 and 3:
Sie Chin Tjong Carbon Nanotube Rein
Page 4 and 5:
Sie Chin Tjong Carbon Nanotube Rein
Page 6 and 7:
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 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 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 115 and 116: 100j 3 Physical Properties of Carbo
Page 119 and 120: 104j 4 Mechanical Characteristics o
Page 147 and 148: 132j 5 Carbon Nanotube-Ceramic Nano
Page 155: 140j 5 Carbon Nanotube-Ceramic Nano
Page 201 and 202: 186j 7 Mechanical Properties of Car
Page 207 and 208:
192j 7 Mechanical Properties of Car
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Table 8.1 Patent processes for maki
Page 233 and 234:
218j 8 Conclusions development of c
Page 235 and 236:
220j 8 Conclusions Figure 8.2 TEM m
Page 237 and 238:
222j 8 Conclusions increase in Vick
Page 239 and 240:
224j 8 Conclusions References 1 Cha
Page 241 and 242:
226j 8 Conclusions nano-matrix. Scr
Page 243:
228j Index l laser ablation 7 load
show all

Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

Create successful ePaper yourself

Delete template?

Save as template?