Thesis (Ph.D.). / Written for the Dept. of Mechanical Engineering. Title from title page of PDF (viewed 2009/06/11). Includes bibliographical references.

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Chapter One serves as an introduction to, and background information, on the thermal decomposition of metal oxalates and homonucleus carbonyl clusters. Emphasis is placed on the compounds under investigation, namely the oxalates of iron(II), cobalt(lI) and nickel(ll) oxalate dihydrate and their corresponding binary and ternary compounds, as well as triiron dodecacarbonyl and tetracobalt dodecacarbonyl. Topics specifically addressed are their structures as well as the thermodynamics of the dehydration and decomposition of compounds of this type. Given this background, the overall aims of the work are presented. These include finding the reaction conditions to form metal powders from metal oxalates, and a preliminary study of carbonyl clusters to see if they too may be used in the production of metal powders. Chapter Two gives the results of the dehydration and decomposition of the metal oxalates, characterised by way of infrared, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. The compounds under investigation are those of the single oxalates of iron, cobalt and nickel; the binary systems of Fe-Co, Fe-Ni and Co-Ni, in the molar ratios of 3:1, 1:1 and 1:3 for each system; and the ternary oxalate system in the molar ratios of Fe1 :Co1 :Ni1, Fe8:Co1 :Ni1, Fe1 :Co8:Ni1 and Fe1 :Co1 :Ni8. It was found that under certain reaction conditions all these compounds, excluding the ferrous oxalate dihydrate, decompose to the metal. It was found through experiments to modify the morphology of the crystals under investigation that the decomposition product is controlled by the crystal lattice system the starting material is synthesised in. When in the cobalt/nickel oxalate a-crystal system, decomposition is to the metal, or in the case of the binary and ternary systems, to the alloy. If the oxalate is synthesised in the crystal system of the iron oxalate, the resultant decomposition product is the respective oxide. Experiments were carried out on the iron/cobalt binary system to prove this hypothesis. Depending on the conditions of synthesis, the iron/cobalt binary system can form in either the crystal system analogous to iron (1), or analogous to cobalt (2). The products of pyrolysis for each case differs, with (1) decomposing to the oxide and (2) decomposing to the alloy. iii Chapter Three is a brief, preliminary study describing the thermal decomposition of triiron dodecacarbonyl and tetracobalt dodecacarbonyl. Characterisation of the pyrolysis products is given by infrared, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. A tentative theory for their decomposition route under an atmosphere of nitrogen is given. It was found that neither compound decomposed fully to the central metal, but that a mixture of oxide and metal were left. The conclusion reached from this study was that neither carbonyl under investigation was particularly successful. Although in both instances metal was produced, both contained large amounts of the respective oxide. This makes them unsuitable for an industrial application to form metal powders. Chapter Four describes in detail the all the experimental, materials, methods, techniques and equipment used in this study. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 220-229).

Bulk nanostructured silver components were fabricated from nano-sized powder using a shockwave consolidation technique. The grain size evolution during compaction, the mechanical properties of the bulk components, and the effect of surface finish on the mechanical behavior were studied. X-Ray diffraction, transmission electron microscopy (TEM), atomic force microscopy (AFM), microhardness, compression testing and shear punch testing at room temperature were used to characterize the materials. Upon consolidation, the average grain size calculated from image analysis of the TEM micrographs was 49+/-22 nm, showing the feasibility of maintaining a nanostructure upon dynamic consolidation. The hardness of the bulk nanostructured components was constant across the diameter with an average of 83+/-1 HV. Compression results showed strength about 390+/-10 MPa and ductility of 23+/-2%, which is well above strength level obtainable from strain hardened Ag components. The AFM results show that samples possessing a surface roughness of 267 nm exhibited a brittle behavior and a reduction in strength of 35% when compared to the smoother surfaces. Dimples were observed for the samples exhibiting plasticity, while an intergranular pattern was identified for the brittle materials. Fracture toughness of 0.2 MPa m was calculated, which confirms the strong relationship between fracture toughness and defects observed in nanomaterials.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 281-306). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 14, 2006) Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 10, 2007) Vita. Includes bibliographical references.

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