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  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 265-272 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Surface oxidation reactions of cobalt, molybdenum and mixed cobalt-molybdenum metals have been investigated using x-ray photoelectron spectroscopy (XPS). The oxide stoichiometries have been determined from XPS intensity measurements. Such quantification has been important in identifying oxide compositions with characteristic XPS spectra. A number of discrete binary molybdenum oxides have been characterized after reactions at 200°C and pressures ranging from 1 atm to 10-6 Pa. At the lowest pressure, the Mo 3d spectra and O/Mo ratios suggest the formation of a molybdenum-oxygen structure with a stoichiometry near unity. By contrast, at higher pressures, oxides that are predominantly MoO2 and MoO3 appear, but other intermediate oxide structures are also identified. Well-defined binary oxides of cobalt can be prepared from cobalt metal after heating in oxygen at different pressures. New binary oxides of cobalt and molybdenum have been generated by the reaction on MoO3 or Co3O4 substrates. Oxidation of a thin film of molybdenum on a Co3O4 substrate has been shown to produce a nearly stoichiometric surface layer of CoMoO4. The procedure could be useful for the production of other ternary oxides of possible interest for use as XPS reference materials.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 10 (1981), S. 153-153 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 143-150 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Extended chain polyethylene fibres have been treated in ammonia and oxygen lo-pressure gas discharges (plasmas) in order to enhance adhesion to epoxy and unsaturated polyester resins, respectively, and thus significantly improve fibre/resin interfacial properties in fibre-reinforced polymer composites. Ammonia plasma treatment results in the incorporation of amine functional groups onto the fibre suface. The treated fibre surface has been analysed using XPS and spectrophotometric techniques. Extended chain polyethylene/epoxy composites made from ammonia, plasma-treated fibres show a marked increase in interlaminar shear strength over composites made from untreated, corona-treated or oxygen plasma-treated fibres. The increase in fibre/resin adhesion after ammonia plasma treatment is confirmed by SEM observations of fracture surfaces, which show clean interfacial fracture surfaces in composites made from treated fibres. Fibres modified by oxygen plasma treatment contain a significant concentration of carbon-oxygen functionalities, which contribute to the polarity of the surface and hence increase wet-out by unsaturated polyester resins. The concentration and nature of carbon-oxygen species on the fibre surface have been determined by XPS. Pull-out tests on multifilament yarns embedded in a polyester resin confirm the high fibre/matrix adhesion achieved with the oxygen plasma-treated fibres compared to corona-treated or untreated fibres. Tensile properties of the fibres are reduced significantly after prolonged treatment in an oxygen plasma, while in an ammonia plasma the fibre strength is unaffected.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 10 (1981), S. 138-146 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: It is shown that the depth distribution of X-ray production in the electron microprobe can be accurately described by a Gaussian modified at the sample surface by a transient. Assuming that the Gaussian is a consequence of the electrons undergoing a random walk in the sample and that the transient corresponds with the change from collimated to random electron trajectories enables theoretical values for the amplitudes and coefficients of the two functions to be predicted. There is excellent agreement between the predicted and the observed values. The Lenard coefficient and the electron range can both be estimated from the coefficient in the Gaussian. It is suggested that for microprobe work, Lenard's law for electron absorption be replaced by this revised law. Both the absorption and atomic number corrections of the traditional ZAF approach are replaced by the new function.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Fire and Materials 18 (1994), S. 167-172 
    ISSN: 0308-0501
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A cone calorimeter is used to determine the fire performance of polymer composite materials containing combustible reinforcing fibres in addition to combustible matrix resins. Extended-chain polyethylene and aramid fibre-reinforced composites containing epoxy, vinylester and phenolic matrix resins are examined at various cone irradiances. Values for time to ignition, rate of heat release, effective heat of combustion, smoke density and evolved carbon monoxide and carbon dioxide are reported for the reinforcements, matrix resins and composites. The reinforcements have a significant effect on the fire-hazard properties of the composite materials. For the epoxy and vinylester composites, times to ignition reflect those of the component of higher ignitability. This was not the case for the aramid-reinforced phenolic composite, in which the resin surface layer hinders combustion of the fabric reinforcement. Resin and reinforcement contributions to the composite rate of heat release behaviour as a function of time are generally discernible.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 11 (1982), S. 187-193 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Gaussian expression for φ(ρz) has been used as the basis of a computer program for quantitative electron probe microanalysis. Corrections for absorption and atomic number are combined within the expression for φ(ρz) whereas the fluorescence correction is based on numerical integration over the primary and secondary intensities. Error histograms based on about 500 published analyses of standard specimens have been used to adjust the parameters in the Gaussian expression for optimum accuracy. The resultant error histograms are as narrow as those obtained for the most accurate of the current ZAF correction procedures. Extension of the method to non-normal electron incidence is relatively straightforward.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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