Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 49-50).

Thesis (Ph.D.)--Victoria University of Wellington, 2007. / Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 150-153).

Thesis (Ph. D. in Interdisciplinary Materials Science)--Vanderbilt University, Aug. 2007. / Title from title screen. Includes bibliographical references.

published_or_final_version / abstract / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

M.Sc., Faculty of Science, University of the Witwatersrand, 2011 / In this work, the primary investigation has been on the development of the laser pyrolysis setup and its optimization for the synthesis of nano-size VO2-x films. More specifically the focus was on making VO2-x depositions using various laser pyrolysis parameters and establish in this way (1) an optimum laser wavelength threshold for the photon induced dissociation of the molecular precursors while the thermal contribution was kept minimal by using low power density (laser energy of 30 W) and (2) the lower threshold for pure thermal contributions by working with wavelengths far from resonance in order to minimize pure photon induced contributions. The interest in synthesizing nano-size VO2-x materials stems from the low metal-insulator transition temperature at near room temperature with opto-electronic and thermo-electronic properties that can be used in specialised applications. A large number of samples were synthesized under various conditions and annealed under argon atmosphere for 17 hours. XRD analysis identified the VO2 (B) and/or β-V2O5 vanadium oxide phases characteristic for certain samples grown under optimum conditions. Raman spectroscopy also confirmed these vanadium oxide phases with bands observed at 175, 228, 261, 303, 422 and 532 cm-1. SEM analysis revealed a plethora of different nanostructures of various size and shapes. The particles have a range of sizes between 55 nm to 185 nm in diameter. The particles showed morphologies which included nano-rods, nanospheres and nano-slabs. An interesting phenomenon was observed on the samples synthesized with high power density, which was observed and reported by Donev iii et al. EDS analysis on the particles was also used to probe the elemental composition of the sample. Optical studies were performed on the samples which showed transitions in the visible and infrared region in accordance with the ones observed in the international literature using different nano-synthesis methods.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2014. / This study concentrated on two main thrusts: 1) the optimal synthesis and characterisation of various micro- and nanosized carbon materials and 2) a comparative investigation of the capabilities of these carbonaceous materials to reinforce a locally available styrene butadiene rubber (SBR), which was commonly used to make car tyres. In the former case, a range of carbon materials including nitrogen doped/undoped carbon nanotubes as well as carbon microspheres (CMSs) were successfully synthesized by two different techniques (i.e. chemical vapour deposition (CVD) and hydrothermal synthesis). These were then fully characterised by numerous techniques which included: TEM, TGA, FTIR, PXRD, laser Raman spectroscopy, Zeta potential measurements and BET surface area analysis. In the latter case, these micro and nanocarbon materials were systematically added to SBR at various loadings (ranging from 0.125–0.500% (m/m)). Here the tensile strengths of the resultant composites, loaded with these various micro and nanocarbon materials, were measured for comparison to establish which (if any) was the best reinforcement material for SBR. Results obtained from the tensile strength measurements of the variously loaded SBR composites, showed that irrespective of the method of synthesis (i.e. CVD or hydrothermal synthesis) carbon microspheres (undoped, doped, functionalised or unfuntionalised) performed more poorly as fillers than carbon nanotubes. Furthermore the results obtained, from the various characterisation techniques mentioned previously, indicated that the lower performance of these microspheres as fillers may have been due to their: size, shape and low surface areas. By contrast when the tensile strengths of SBR reinforced with either CNTs or NCNTs were measured, the former outperformed the latter as fillers. It was speculated, based upon the data obtained, that NCNTs were poorer fillers than CNTs due to their higher negative surface charges, larger diameters and lower crystallinity. Hence this study has shown that low loadings (i.e. 0.250 % (m/m)) of the correctly matched type of carbonaceous material can significantly enhance the tensile strength and Young’s modulus of a locally available styrene butadiene rubber.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015. / The synthesis and applications of carbon nanomaterials (CNMs) such as carbon nanofibres (CNFs), carbon nanotubes (CNTs) and carbon nanospheres (CNSs) have attracted a lot of attention due to their unique chemical and physical properties. For the synthesis of CNMs with desired morphology to occur, one needs to consider three components, namely, the catalyst, carbon source and source of power. However, the cost of the catalysts involved in making CNMs is one of the challenging factors. Due to properties such as high aspect ratio, CNM use as fillers in polymer nanocomposites has been on the forefront to improve the mechanical strength of polymer materials such as polyesters. Due to their hydrophobic nature, the interaction between the filler and matrix tends to be problematic. In this study, we investigated the use of a waste material, coal fly ash as a catalyst for the synthesis of CNMs using the chemical vapour deposition method. The use of CO2 and C2H2 as carbon sources, either independently or together, was also employed. A comparison of two different ashes was also investigated. Lastly, the use of these synthesized and acid treated CNMs as fillers was examined. The catalysts and synthesized CNMs were characterised using SEM, TEM, EDS, laser Raman spectroscopy, XRD, BET, TGA and Mössbauer spectroscopy. The mechanical properties were investigated by testing the tensile, flexural and impact properties. The synthesis of CNMs using fly ash as a catalyst without pre-treatment or impregnating with other metals was achieved. Optimum yields and uniform morphology was obtained at 650 oC, at a flow rate of 100 ml/min using H2 as a carrier gas and C2H2 as a carbon source. Mössbauer spectroscopy revealed that cementite (Fe3C) was the compound responsible for CNF formation. Further, CNMs were formed over fly ash as a catalyst, using CO2 as a sole carbon source, an additive and a carbon source before reacting with C2H2. Duvha was Page | iii found to be a better fly ash catalyst compared to Grootvlei and an optimum loading was achieved at 0.25%. Treating the CNFs with HCl/HNO3 resulted in the highest tensile, flexural and impact strengths. This study / GR 2016

Tsui Pui Yuen = 納米鈀硅合金比容的硏究 / 徐沛源. / Thesis submitted in 2000. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Tsui Pui Yuen = Na mi ba gui he jin bi rong de yan jiu / Xu Peiyuan. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgments --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- A New Age of Materials --- p.1 / Chapter 1.2 --- Nanocrystalline Materials --- p.1 / Chapter 1.3 --- Fabrication of Nanocrystalline Materials --- p.2 / Chapter 1.4 --- Phase Transformation --- p.3 / Chapter 1.5 --- Nucleation and Growth --- p.5 / Chapter 1.6 --- Spinodal Decomposition --- p.7 / Chapter 1.7 --- The Relation of Undercooling and the Morphology of SD --- p.9 / Chapter 1.8 --- Method to Obtain Large Undercooling --- p.9 / References --- p.11 / Figures --- p.12 / Chapter Chapter 2 --- Experimental --- p.19 / Chapter 2.1 --- Method --- p.19 / Chapter 2.2 --- Preparation of Fused Silica Tubes --- p.19 / Chapter 2.3 --- Sample Preparation --- p.19 / Chapter 2.3.1 --- Alloying --- p.19 / Chapter 2.3.2 --- Fluxing --- p.20 / Chapter 2.3.3 --- Controlled Undercooling --- p.20 / Chapter 2.4 --- Analyzing Method --- p.20 / Chapter 2.4.1 --- Measurement of density --- p.20 / Chapter 2.4.1.1 --- Theory --- p.20 / Chapter 2.4.1.2 --- Experimental Setup --- p.21 / Chapter 2.4.2 --- Microstxucture Analysis --- p.21 / References --- p.23 / Figures --- p.24 / Chapter Chapter 3 --- Results and Discussions --- p.28 / References --- p.32 / Table --- p.33 / Figures --- p.34