Browsing by Author "Yuanzheng, Yue"

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    Progress in the rheology of glass melts - A survey
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Brückner, Rolf; Yuanzheng, Yue; Deubener, Joachim
    The rheology of glass melts is not restricted to Newtonian viscous flow, but it involves also non-Newtonian flow and viscoelasticity The former one predominates in the steady-state flow at low deformation rates, the latter ones prevail during the initial State of stress generation and during the final State of flow and fracture under extreme deformation conditions. The whole ränge of rheological phenomena is demonstrated in this review article. Typical available experimental results and mathematical formulations are briefly given for single-phase glass melts. In this context the development of new equations gives rise to the introduction of a series of new definitions and conceptions which physically and mathematically characterize the different rheological behaviour of glass melts under various stress-strain conditions. The connection between flow behaviour and structural aspects is pointed out with a short reference to flow birefringence. Finally, an extension from the behaviour of a single-phase to a double-phase system is developed for the case of suspended crystals with defined sizes, concentrations and shapes within an inert glass melt (model for glassceramic melts).
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    Redox behaviour of iron bearing glass fibres during heat treatment under atmospheric conditions
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Kirkegaard, Lisa Frank; Korsgaard, Martin; Yuanzheng, Yue; Mørup, Stehen
    Systematic pre-oxidation experiments in the glass transition region have been carried out on iron bearing aluminosihcate glass fibres in air. The pre-oxidized fibres are up-scanned in a simultaneous thermal analyser to a temperature of 1273 Κ under atmospheric conditions in order to measure the increase in mass, which is a consequence of the oxidation of ferrous iron to ferric iron. Based on the Mössbauer spectroscopic measurements, an approach has been proposed to calculate the redox State of the iron from the increase in mass of the fibres. The quantitative relationships have been found between the redox State of the fibres and both the pre-oxidation temperature and the pre-oxidation duration. These relationships can be used to predict the degree of oxidation of the fibres by knowing the heat treatment conditions and vice versa.