Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

More documents

Recommendations

Info

5.4.3 Titania Matrix Titania (TiO2) is a semiconducting oxide with high photocatalytic ability. It finds application in many technological areas such as microelectronics, photocatalysis and sensors [95–97]. Titania is also an important bioceramic coating material for metal implants due to its excellent biocompatibility [98, 99]. Incorporating CNTs into titania can lead to the development of novel composite materials with advanced functional properties for photocatalytic, microelectronic and biomedical applications [100]. The techniques used for forming titania-CNT nanocomposites include heterocoagulation, sol-gel and hydrothermal treatment. Sun and Gao employed heterocoagulation to deposit titania on MWNTs [62]. In the process, ammonia-treated MWNTs were dispersed ultrasonically in water containing cationic PEI. Titania nanoparticles with sizes less than 10 nm were dispersed in water under sonication and the pH value was adjusted by adding NaOH. Titania drops were then added to the nanotube suspension under a pH of 8. Figure 5.24 shows the zeta potential vs pH curves for titania and NH 3-treated MWNTs measured in 1 mM NaCl solution. For zeta-potential measurements, the pH was adjusted with HCl for acidic suspension and with NaOH for basic suspension. Electronegative titania nanoparticles are attracted to positively charged surfaces of MWNTs, thereby forming a titania coating layer on the nanotube surface (Figure 5.25). In another study, Sun et al. coated SWNTs with titania nanoparticles by using TiCl4 precursor and PEI surfactant by the hydrothermal method [101]. Titania nanoparticles were formed by the hydrolysis of TiCl4 solution through the following reaction: TiCl4 þ 2H2O ! TiO2 þ 4H þ þ 4Cl : ð5:1Þ Figure 5.24 Zeta potential as a function of pH for titania and treated MWNTs with PEI. Reproduced with permission from [62]. Copyright Ó (2003) Elsevier. 5.4 Oxide-Based Nanocompositesj155
156j 5 Carbon Nanotube–Ceramic Nanocomposites Figure 5.25 TEM image showing titania coated MWNT surface. Reproduced with permission from [62]. Copyright Ó (2003) Elsevier. Acid-purified SWNTs were then added to the TiCl4 suspension. PEI addition is beneficial to assist the deposition of titania on nanotube surfaces. Jitianu et al. employed both sol-gel and hydrothermal techniques to coat titania on MWNTs [102]. For the sol-gel process, alkoxide precursor, that is, titanium tetraethoxide Ti(OEt)4 or titanium tetra-isopropoxide Ti(OPr)4) was mixed with ethanol/ isopropanol, water and nitric acid to form a titania sol under magnetic stirring. MWNTs were then mixed with the sol under stirring. The impregnated MWNTs were separated from the solution by filtration. For hydrothermal treatment, the precursor consisted of 15 wt% TiOSO4 in diluted sulfuric acid. MWNTs were then added to the TiOSO4 solution in water. Hydrothermal treatment was performed in an autoclave at 120 C for 5 h. Impregnated nanotubes prepared by the sol-gel and hydrothermal methods were further dried at high temperatures. MWNT surfaces prepared by solgel using Ti(OEt)4 precursor are coated with a continuous thin film (Figure 5.26(a)), and with TiO2 nanoparticles in the case of Ti(OPr)4 (Figure 5.26(b)). The microstructure of titania coated nanotubes prepared by hydrothermal method is shown in Figure 5.26(c). 5.4.4 Zirconia Matrix Zirconia-based ceramics are well recognized for their excellent mechanical, electrical, thermal and optical properties. They find a broad range of industrial applications including oxygen sensors, solid oxide fuel cells and ceramic membranes [103, 104]. The physical and mechanical properties of ziroconia can be further enhanced by adding low loading level of CNTs. Zirconia-CNT nanocomposites can be fabricated by hot-pressing [105], heterocoagulation [106] and hydrothermal crystallization [107, 108]. Shan and Gao fabricated ZrO2/MWNT nanocomposites by hydrothermal treatment of ZrOCl2.8H2O. They reported that full coverage of ZrO2 on nanotubes can be prepared only through the use of an acid medium [108]. In a weak alkaline solution, only few zirconia agglomerates adhere to the sidewalls of MWNTs. Hardly any adsorption of zirconia on nanotubes can be observed in a strong alkaline solution. They attributed the formation of zirconia coating on sidewalls of MWNTs to the
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 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
100j 3 Physical Properties of Carbo
Page 117 and 118:
102j 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 169: 154j 5 Carbon Nanotube-Ceramic Nano
Page 185 and 186: 170j 6 Physical Properties of Carbo
Page 201 and 202: 186j 7 Mechanical Properties of Car
Page 221 and 222:
206j 7 Mechanical Properties of Car
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?