Thesis (Ph. D.)--State University of New York at Binghamton, Chemistry Department, 2006. / Includes bibliographical references.

Thesis (Ph. D.)--University of Florida, 1975. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 175-188).

Thesis (Ph. D.)--University of Pennsylvania, 1908.

Thesis (Ph. D.)--University of Pennsylvania, 1908.

Proefschrift Groningen, Rijksuniversiteit. / Met lit. opg. en een samenvatting in het Nederlands.

No description available.

An investigation of the characteristics of yielding and flow in polycrystalline and single crystal vanadium has been carried out. The effect of grain size, temperature and strain rate on these properties was studied. It was found that there is no similarity between the mechanisms of yielding and flow, in vanadium which is in disagreement with work on iron. The results of tensile tests suggest that the mechanism controlling thermally activated flow is probably either the Peierls-Nabarro force or the non-conservative motion of vacancy jogs. Some inadequacies of these mechanisms suggest that there may not be a single mechanism controlling thermally activated flow. Yield points were observed in the stress-strain curve upon reloading a tensile specimen under certain conditions and these are explained in terms of Snoek ordering. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

[No abstract submitted] / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

An investigation of the low temperature tensile properties of vanadium and vanadium-rich alloys has been carried out. The metals and alloys used in this investigation were prepared in ingot form by levitation melting and casting techniques. Thin strip specimens of vanadium, vanadium-titanium and vanadium-aluminum alloys were tested in tension at temperatures from 23°C to -196°C and at a constant strain rate of 5.55 X 10⁻² min.⁻¹. The results have indicated that polycrystalline vanadium of the purity employed in this study, does not show a ductile-to-brittle transition behaviour in the temperature range investigated. The variation of yield stress with temperature for pure vanadium has been correlated to Fisher's interpretation of the Cottrell-Bilby theory of yielding. The effects of additions of titanium and aluminum on the room temperature tensile properties and hardness of unalloyed vanadium have been studied. The alloying effects were quite different from those normally observed in binary systems and have been interpreted in terms of the interaction of the alloying elements with interstitial impurities. The effect of alloying additions on the temperature dependence of yield stress have been studied in the range of 23°C to -196°C. The variation of yield stress with temperature has been found to be quite different from that indicated for pure vanadium and to be sensitive to alloy content. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

It has been found that sodium vanadate in aqueous solutions, can he reduced by gaseous hydrogen, at temperatures of 300 - 400°F, and in the presence of a nickel catalyst, and precipitated as an oxide of lower valence. The following reaction has been proposed: 2 VO₃[superscript -] + 2H₂ → V₂0₃ •+ 2OH[superscript -] + H₂O The kinetics of this reaction have been examined, and the following effects observed. (1) Two distinct stages of reduction are involved.In the overall reaction, VO₃ is first reduced to a soluble tetravalent ion, believed to be V₂O₅[superscript =] followed by further reduction to the trivalent oxide which is precipitated. The latter stage is rate controlling. (2) The kinetics of the reaction are initially of zero order, the rate being independent of the concentration of vanadium down to a value of one gram per litre. Below this value the kinetics become first order. (3) The rate is directly proportional to the amount of nickel catalyst present. (4) The rate is proportional to the square root of the pressure of hydrogen. (5) The activation energy for the reaction is 7850 calories per mole. The mechanism of the reaction is discussed in the light of these kinetic results and a rate controlling step is proposed consisting of a reaction between V₂O₅[superscript =] ions and H atoms, both adsorbed on the surface of the nickel. Such a mechanism is consistent with all the kinetic observations. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate