Browsing by Author "Bieniarz, Piotr"

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    Influence of Al2O3, ZrO2 and TiO2 on the properties of the microporous glasses from the system Na2O-B2O3-SiO2
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2003) Procyk, Bernadeta; Dorosz, Dominik; Bieniarz, Piotr; Zawada, Anna; Höhne, Diethard
    Glasses from the Na2o-B2O3-SiO2 system, doped with AI2O3, ZrO2 and TiO2, were thermally (in the temperature range of 420 to 700 °C) and chemieally treated. During thermal treatment, separation of the borate phase from the silica skeleton occurrred resulting in the formation of an interconnected microstructure. The borates were in the form of small drops joined to each other. In the course of chemical treatment the borates were leached in water and water solutions of acids or bases with the glass becoming very porous. The experiments showed that ZrO2 and TiO2 caused an increase in pore diameter at defmite leaching times. AI2O3, however, decreased it, so that glasses doped with AI2O3 have a greater specific surface. In this case a double-pore distribution occurred. Porous glasses may find application in many branches of science and engineering. The applications depend on the internal arrangement, size and shape of pores. These parameters may be in a wide range modified by a change of the chemical composition. Testing structure and properties of microporous glasses from the system Na2O-B2O3-SiO2 with different additions was the main aim of this work. The following testing methods were applied: DTA, XRD, TEM, infrared spectroscopy and sorption porosimetry.
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    Influence of redox equilibrium on the properties of glasses with a high iron concentration
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Zawada, Anna; Hessenkemper, Heiko; Höhne, Diethard; Bieniarz, Piotr
    In glasses of the System Na2O-CaO-SiO2-Fe2O3, Fe2+ and Fe3+ ions were found by Mössbauer spectroscopy. In samples melted in oxidizing atmosphere, both ions occurred in tetrahedral coordination, whereas they occurred in coordination number 6 in samples with high iron content and melted under reducing conditions. It is shown that a total iron concentration has a stronger influence on the glass properties than the redox state. Differences in the properties of glasses melted in oxidizing and reducing atmosphere, respectively, were observed at lower temperatures, while at higher temperatures they are very small (however, the tendency is still maintained). Density, microhardness, transition temperature and thermal expansion coefficient of the glasses studied are affected by the changes in redox equilibrium. One can conclude that after reducing treatment iron ions present in the glass structure play a similar role as a network modifier. At higher temperatures, this kind of activity is very weak, according to viscosity and liquidus temperature measurements.
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    Processing of molten solid residues
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Bieniarz, Piotr; Höhne, Diethard; Hessenkemper, Heiko; Zawada, Anna
    An alternative way of recovery, recycling and re-integration of solid wastes on a laboratory scale is demonstrated. The analysed synthetic slags belong to the System SiO2-Al2O3-CaO-MgO-Fe2O3-K2O-Na2O. A polynomial model has been developed by means of a computing program in order to calculate some important technological features directly from a variable oxide concentration and to determine a processable composition. Furthermore, a concept of maximum application of the residues is suggested for slags from waste incineration and other industrial processes with relative low volatile components. Rolling has been chosen as the most suitable forming technique, because recycling melts show a short forming interval and an aggressive behaviour towards refractory materials. It is possible to form plates or tiles which afterwards can additionally be shaped e.g. to create profiles or breaking points. Because of their affmity to crystallization the glassy end-products can be devitrified at the surface (into semicrystalline products, i.e. glass-ceramics) to receive a better resistance. The present results show the possibility of using well known forming and treating processes to make high value products from low-value by-products, with a considerable economical advantage.