Browsing by Author "Baumann, Patrick"

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    Determination of the corrosion progress of zirconium oxide containing refractories based on the natural intrinsic gamma radiation of the material
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2001) Fleischmann, Bernhard; Baumann, Patrick; Mergler, Kurt Wilhelm
    The determination of the corrosion progress of refractory blocks is interesting for the operation of glass furnace tanks under safety and economic aspects. The measuring principle, based on the very small natural radiation of impurities of the zirconium raw materials for refractory production, has been known since the beginning of the seventies of the last century and could now be developed through improvements of measuring technology and sensors. Smaller changes to a laboratory test setup from medical technology were made both in the hardware and the software, to enable measurements of the intrinsie radiation of fused-cast AZS refractory materials in hot and dusty environment on glass melting furnaces during operation. A measuring schedule was developed and calibrating measurements were carried out with blocks of different zirconia content. First practical tests were made on cold glass furnaces. The final adaptation of the equipment was done with measurements on operating glass furnaces. The measurements of the corrosion progress and/or the residual thickness of refractory blocks based on the natural intrinsic gamma radiation could be done with the expected accuracy and can be used to support the operator of glass melting tanks.
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    Redox behavior of selenium in industrial soda-lime-silica glasses
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2001) Müller-Simon, Hayo; Bauer, Johannes; Baumann, Patrick
    A thermodynamic model for the calculation of the redox distributions of polyvalent elements which is based on the balance of chemically bonded oxygen in glass melts has been applied to the redox reactions of selenium. A set of reliable thermodynamic data of the selenium oxidation reactions has been derived using results of electrochemical, optical and wet-chemical investigations. Calculation results showed that selenium is reduced during cooling by iron as well as by sulfur. Due to the small selenium/sulfur ratio in selenium-decolorized flint glasses under industrial conditions selenium is completely reduced to the selenide state. Obviously, in industrially melted flint glasses selenium decolorization is not provided by the pink color of elemental selenium as assumed so far but by the amber color of iron selenide, which is supported by the fact that selenium decolorization always causes an additional yellow tint besides the required red tint and a considerable shift of the UV edge to larger wavelengths.