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A wide range of lime green/yellow to mustard/orange bismuth orthovanadate samples were prepared via solid state and precipitation techniques. The materials were characterised using thermal analysis, X-ray diffraction, evolved gas analysis, reflectance infra-red spectroscopy, electron microscopy, colour measurement, wet chemical analysis and ac impedance spectroscopy. This product characterisation identified more complex materials than previously reported, with generally non-stoichiometric compositions established. The fergusonite-type polymorph of BiVO₄ was prepared via solid state synthesis. This phase was found to be slightly V-rich in composition, of BiV_1.025O_4+x. It occurs as a line composition and melts congruently at 930°C ± 10°C. A reversible, non-quenchable phase transition from fergusonite to scheelite-type BiV_1.025O_{4 + x} was determined at 240-250°C. The zircon and scheelite-type polymorphs of BiVo₄ were produced by controlled room temperature precipitation, at pH 1-2 and 3-7 respectively, whereas the fergusonite-type polymorph was obtained at pH 1-7 on precipitation from solutions at 95°C. All three precipitated polymorphs were found to contain a proportion of foreign ions, totalling 2.0-3.0, 2.7-3.6 and 0.3-0.9 weight% for the zircon, scheelite and fergusonite-type polymorphs respectively. These foreign ions consist of adsorbed water and structural nitrate, carbonate and hydroxyl constituents. Chemical analysis identified essentially Bi-rich compositions for the precipitated polymorphs. An irreversible phase transition from zircon to scheelite-type BiVO₄ was determined at 500-520°C. BiVO₄ is studied as a possible alternative yellow pigment for the toxic cadmium and chrome-containing traditional yellow colourants. The sample colours obtained were compared with those of the commercial CdS, PbCrO₄ and BiVO₄/Bi₂MoO₆ pigments. Polycrystalline, phase pure BiV_1.025O_{4 + x} ceramics, prepared by solid state synthesis were investigated using ac impedance spectroscopy. These materials were found to exhibit mixed oxide ion/electronic conduction at both low and high temperatures, ie. <400°C and >600°C. Oxide ion conductivity dominates the temperature region between 400 and 600°C, with an activation energy of 0.80 + 0.01eV. The bulk conductivity below 400°C was found to be metastable and influenced by the presence of water. The possibility of protonic conduction below 400^OC is identified.

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This thesis reports investigations into laser ablation inductively coupled plasma emission spectrometry for rapid elemental analysis of a diverse range of samples: glasses, aqueous solutions, oils, coated steels and glasses, and biological samples. Bulk analysis of glasses for major, minor and trace elements is reported. Results showed that element emission responses are dependent upon laser operating conditions. With optimised operating conditions of a Q switched laser operating at 60 J for 5 s ablation time with the laser defocused by 5 mm above the sample surface. The limits of detection are in the sub ug g -1 level with precision ranging from 6.6 %RSD for a non volatile element such as boron to 23 %RSD for a volatile element silver. Although the principal aim of using aqueous multielement solutions as novel calibration standards for quantitative analysis of other liquids was not achieved, optimised laser operating parameters needed for microsampling of aqueous solutions and analytical performance data were obtained. The optimum laser operating conditions for a 20 ul sample were found to be the same as for glasses and were as follows: a Q switched laser operating at 60 J for a 5 s ablation time with the laser defocused by 5 mm above the sample surface. Transport efficiencies of approximately 30 % can be achieved, compared to < 1% by pneumatic nebulisation. Also there was no differential loss of elements by laser ablation which may occur with electrothermal vaporisation. Limits of detection were found to be in the sub ug ml -1 level. Precisions were typically between 6.6 and 12 %RSD. The main cause for lack of precision was spattering of the sample. Microsampling of oils by laser ablation proved to be an effective and accurate technique for rapid determination of element concentration without the need for sample filtration or digestion. Precision proved to be better than for aqueous solutions, typically from 3 to 7 %RSD, because of a reduction in spattering. The same optimum laser operating conditions used for aqueous solutions were identical for oils. This thesis reports the first experiments to fully utilise laser ablation as a routine method for quantitative measurement of coating depth for coated steels and glasses. It was found that the peak width at half the maximum height was proportional to the coating thickness (over a range of 1 to 10 um). With optimised laser operating conditions a depth resolution of less than 1 um was achieved. The optimum laser operating conditions were as follows: a Q switched laser ran continuously with a laser lamp energy of 60 J at 10 Hz pulse repetition rate. Finally experiments show the great potential for the use of laser ablation as a microsampling technique for microtome tissue samples. Micro depth analysis of nickel distribution in skin shows that the technique could differentiate between two skin samples with different nickel concentrations. The use of gel multielement standards as a novel calibration technique for analysis of microtome tissue samples has also been demonstrated. Optimum laser operating condition were to use a moderate laser energy of 750 V with the laser defocused 5 mm above the sample surface.

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Coatings are added to components to provide enhanced protection from the surroundings or to recondition them after the surfaces have been damaged. But the change in conditions at the surface will often lead to a change in the resistance to fatigue loading. This investigation is focused on the behaviour of shouldered shafts electroplated with nickel, chromium and a cobalt/chromium carbide composite. Changes, in fatigue strength are demonstrated. Each of the materials has a unique effect on the behaviour of a shaft, although there is a similarity which can be utilised in design. Each can reduce the fatigue strength by a substantial amount, but it is possible to optimize the design of a new shaft so that its strength is not significantly different to that of an uncoated version. The composite coating has the least effect. Explanations for these effects are given, based on differences in the mechanical properties of the substrate and coating materials, the distribution of residual stresses within the materials, and the interaction of these factors with the applied stress profile. Recommendations and methods of analysis which can be used in the design of coated components are presented. The contribution of the manufacturing processes is discussed, and grinding is highlighted as a dominant factor. Gentle grinding procedures are shown to produce ideal conditions by inducing large compressive residual stresses in the surfaces. Radial plots of the residual stresses have been produced. These were obtained by techniques based on Sachs' method, using electrochemical machining and an extended analysis developed for use with coated parts. The stress distributions were not affected by fatigue limit loading, indicating that stress relief methods using amplitudes of this order are ineffective and unsafe.

Intumescent coatings are used in the field of fire protection to prevent certain construction elements reaching the critical temperatures at which excessive damage would. occur, thus avoiding premature structural collapse. The studies presented in this thesis have been directed towards an understanding of intumeseent coatings and the process of intumescence. The kinetics and mechanism of intumeseence are discussed. The behaviour of the raw materials used in the preparation of intumeseent coatings, was studied at elevated temperatures using thermal analytical techniques, and new formulations were developed. These formulations were examined In the laboratory using various screening tests and were also subjected to a large scale hydrocarbon fire test alongside other commercially-avallable coatings. A simplified coating formulation with the minimum of ingredients required to produce good intumescent properties was developed. This formulation was subjected to various heat-radiation intensities using an ISO ignitablilty apparatus. The behaviour of the intumescence, process observed was explained by a simple theoretical model. The model of Buckmasterv Anderson and Nachman was used and several new results were derived. In particular a relationship was derived giving the time taken for the temperature at the inner surface of the coating to reach a given value. The durability of the newly-developed intumescent coatings, and methods of improving it, were also investigated.

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Urethane-acrylic copolymers have found increasing use as a radiation curable materials in the recent years. These copolymers are highly crosslinked through the use of acrylic monomers having more than one double bond. Stirling Lloyd had discovered such materials to be a successful alternative to the urethane or acrylics coatings as waterproof membrane coatings. In this project, structure-property relationships of UA copolymer systems were studied. These were peroxide cured at room temperature.