Browsing by Author "Filonenko, D. V."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Properties and Structural Characteristics of Glasses in the SrO–BaO–Al2O3–B2O3–SiO2 System for Dielectric Composite Materials
    (Ukrainian State University of Chemical Technology, Dnipro, 2024) Amelina, O. A.; Zaichuk, Oleksandr V.; Hordeieiv, Y. S.; Filonenko, D. V.; Kalishenko, Y. R.
    ENG: Ceramic materials synthesized within alkali-free aluminosilicate systems are widely used as dielectrics in microelectronics, radio engineering, aviation, and rocket technologies. The addition of glass binders to these ceramic compositions significantly reduces the sintering temperature by promoting liquid phase formation at lower temperatures. This study investigates the effect of substituting SrO with BaO on the properties and structural characteristics of glasses in the SrO–BaO–Al2O3–B2O3–SiO2 system. It is found that replacing up to 20 mol.% of SrO with BaO enhances the glass-forming ability and promotes the formation of monoclinic strontium anorthite during crystallization. Additionally, strontium anorthite forms a solid substitutional solution with celsian due to the close ionic radii of Sr2+ and Ba2+ ions. This similarity in ionic size and charge ensures that the basic structural units of the glass network remain unchanged. Moreover, increasing the BaO content to 20 mol.% reduces the coefficient of thermal expansion of the glass from 78⋅10–7 оС-1 to 71⋅10–7 оС-1, while slightly increasing the density from 3.20 g/cm3 to 3.34 g/cm3. The volumetric electrical resistance at 300 оС ranges between 1010.7 and 1011.6 ohm⋅cm, demonstrating the excellent insulating properties of these experimental glasses. The properties of the investigated glasses allow considering them as components of dielectric composite materials that can significantly intensify sintering processes.
  • Thumbnail Image
    Item
    Thermodynamic Analysis of the Reactions of Strontium Anorthite Formation during the Firing of Thermal Shock Resistance Ceramics Based on the Eutectic Glasses of the SrO–Al2O3–SiO2 Systems
    (Ukrainian State University of Chemical Technology, Dnipro, 2023) Zaichuk, Oleksandr V.; Sukhyy, Kostyantyn M.; Amelina, O. A.; Hordeieiv, Y. S.; Filonenko, D. V.; Rudnieva, L. L.; Sukha, Iryna V. ; Halushka, S. A.
    ENG: Thermal shock resistance ceramic materials must have a high degree of sintering to ensure the required mechanical strength, erosion resistance, and resistance to high-temperature oxidation. However, the search for effective ways to achieve a high degree of sintering of ceramic materials based on the SrO–Al2O3–SiO2 system at low temperatures requires a large amount of experimental research. The aim of this work is to analyze thermodynamically the reactions of strontium-anorthite phase formation at the points of triple eutectics of the SrO–Al2O3–SiO2 system under low-temperature firing conditions. The eutectic points were selected in the region of strontium anorthite crystallization and had a temperature not exceeding 14000C. It has been established that in the case of compliance with the stoichiometric ratio, the final product of the interaction of the components of eutectic glasses S-1 and S-2 with the charging components is the strontium anorthite phase. The most probable is the formation of strontium anorthite in the interaction of eutectic glass components with Al2O3∙2SiO2, which is a product of kaolinite dehydration (Al2O3∙2SiO2∙2H2O). It has been found that the compounds SrO∙SiO2 and 2SrO∙Al2O3∙SiO2 are most active in the interaction with the charging components in the direction of formation of the strontium anorthite phase than SiO2 tridymite. As a result, the sintering of strontium-anorthite compositions at a temperature of 9000C causes a significant increase in the content of the crystalline phase of strontium anorthite. The determined patterns allow making a reasonable choice of glass in the SrO–Al2O3–SiO2 system for the further manufacture of low-temperature strontium-anorthite ceramics.