Browsing by Author "Zaichuk, Aleksandr V."

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    Low-Temperature Cordierite Ceramics with Porous Structure for Thermal Shock Resistance Products
    (Elsevier, 2024) Khomenko, Olena S.; Zaichuk, Aleksandr V.; Amelina, Aleksandra
    ENG: This article shows the results of the study of low-temperature (1100−1150 °C) porous ceramics of cordierite composition. The technological manufacturing parameters, the features of the microstructural and phase composition of ceramics have been studied. A decrease in the sintering temperature is achieved by appending a part of components using eutectic glass of MgO–Al2O3–SiO2 pseudoternary system. The principle of reactive formation of the structure of the ceramic sample is implemented in the process of its low-temperature firing. The formation of α-cordierite occurs in the process of firing ceramics by means of intensive interaction between eutectic glass components and crystalline fillers, as well as in the result of glass crystallization. By means of the thin layers of the glassy phase, cordierite crystals form a hard base with a branched system of interconnected open pores (30.0−31.3 %). The cordierite-phase crystals, forming the structure of ceramics, have a particle size ranging from 0.2 to 0.3 μm to 1.0−2.0 μm. The specific surface area of the porous cordierite ceramics is in the range of 4.2–4.7 m2/g. The developed cordierite ceramics is characterized by its low coefficient of linear temperature expansion (1.7–2.6)·10−6 °С−1, which determines its high thermal shock resistance (1000−1150°С). The ceramics may be used as filtering elements in high-temperature filtering units, as well as catalyst carriers in the exhaust systems of combustion engines for discharging the sooty component.
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    Structural, Thermal, and Radiation Shielding Properties of Antimony-Doped Zinc Borate Glasses
    (Nature Research, UK, 2025) Hordieiev, Yurii S.; Zaichuk, Aleksandr V.
    ENG: Antimony zinc borate glasses with compositions (45–m)ZnO–(55–n)B2O3–(m + n)Sb2O3 (0 ≤ m, n ≤ 15 mol%) were synthesized via the melt-quenching technique to investigate the impact of Sb2O3 substitution on structural, thermal, and radiation shielding properties. X-ray diffraction confirmed the amorphous nature of the synthesized glass samples. Fourier-transform infrared spectroscopy revealed significant structural rearrangements, including an increase in non-bridging oxygen content with rising Sb2O3 concentrations, as evidenced by the shifting and intensification of characteristic absorption bands. Differential thermal analysis demonstrated that the glass transition temperature decreased from 580 °C to 490 °C with increasing Sb2O3, while the thermal stability parameter (ΔT) improved from 144 °C to 256 °C, particularly when B2O3 was replaced. Density increased from 3.121 g/cm3 to 3.836 g/cm3, and molar volume expanded from 24.01 cm3/mol to 31.16 cm3/mol. Radiation shielding performance was significantly enhanced: at 10 MeV, the linear attenuation coefficient increased from 0.0768 cm−1 to 0.1142 cm−1 (~ 49%) when replacing B2O3 and to 0.0983 cm−1 (~ 28%) when replacing ZnO. The half-value layer decreased from 9.02 cm to 6.07 cm at 15 mol% Sb2O3, confirming improved photon attenuation. Overall, this work offers valuable insights into the interplay between composition, structure, and functional properties in Sb2O3-doped zinc borate glasses.