Browsing by Author "Khomenko, Olena S."
Item Low-Temperature Cordierite Ceramics with Porous Structure for Thermal Shock Resistance Products(Elsevier, 2024) Khomenko, Olena S.; Zaichuk, Aleksandr V.; Amelina, AleksandraENG: 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.Item Protective Coatings for Construction Ceramics as a Factor of Increasing Energy Efficiency and Operational Properties of Products(Latvia University of Life Sciences and Technologies, 2024) Khomenko, Olena S.; Ivchenko, Viktoriіa; Boginska, Ludmyla; Fomenko, GalinaENG: The production of building materials is important for any sector of economy, as they are widely used to create residential, commercial and industrial structures. This is especially true for products such as ceramic bricks, as their environmental friendliness and energy efficiency make them virtually indispensable. However, the higher the energy efficiency of ceramic bricks, the lower their strength and durability. This is due to the porous structure of the material − water gets into the open pores, which causes gradual destruction as a result of freezing and thawing and changes in volume. To reduce the destruction of the outer layer, decorative and protective engobe coatings have been developed that help seal the outer surface of products and prevent moisture from seeping inside. The compositions, rheological and technological as well as physical and mechanical properties of engobe coatings for ceramic bricks with a firing temperature of 950ºC are presented. It is established that the presence of engobe on the surface of the brick, with its rather porous internal structure, allows to reduce water absorption from 14.8 to 3.2% and increase the frost resistance of products from 15 to 65 cycles. The coating opens up the possibility of significantly extending the service life of the brick.