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The results of theoretical and experimental studies of the influence of scale deposits on heat exchange processes in vitrified pipes washed by seawater are presented. Experimental studies have shown that during long-term operation of heat exchangers, minor scale deposits with a layer thickness of up to 0.4 mm are observed on the surface of glass coatings of pipes, while a strong scale layer up to 2 mm thick is formed on the inner surfaces of metal pipes. The practical absence of deposits in vitrified pipes is explained by the increased cleanliness of the glass surface and its resistance to aggressiveness of substances dissolved in sea water. This eliminates the formation of large foci of scale on the glass surface and washing off the formed scale with a stream of seawater.
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Glass-enamel coatings have been modified with nanosized particles, which expands the scope of their application and is a promising direction. It has been established that the introduction of nanosized zinc oxide in the amount of 0.5 wt. % into the composition of the enamel of the Na2O–B2O3–TiO2–SiO2 system imparts antibacterial properties to the coating against gram-positive and gram-negative bacteria. The meaning of the index of antibacterial activity of the surface of the enamel increases on average five times more in relation to Escherichia coli (E. coli) and six times more in relation to Staphylococcus aureus (St. aureus) compared with a control sample that does not contain zinc oxide.
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The main directions of application of flexible heat insulating materials and traditional technologies for producing non-woven materials are considered. Various ways of fastening fibers are analyzed, such as: chemical; thermal; mechanical, which in turn includes the following options: needle-punched, knitting-stitching, hydro-jet method used in the production of flexible fibrous thermal insulation. A number of patents are presented that develop methods for obtaining nonwoven materials.
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We have obtained the X-ray total scattering patterns at wavelength 0.20735 ? and corresponding to them radial distribution functions (RDF) of electron density for glasses in the La2O3–Nb2O5–B2O3 and BaO–Nb2O5–P2O5 systems. The RDF demonstrate separate peaks at distances below ~1 nm which points on the middle range ordering in the considered glasses. The consideration of RDF for BaO–Nb2O5–P2O5 glasses system with high concentration of BaO show that the middle range order is caused by the polyhedra chains of ideal BaO crystal, and these chains does not belong to any low-index crystal plane. For La2O3–Nb2O5–B2O3 glasses system the polyhedra chains are observed which resemble those in the LaB3O6 crystal, with polyhedra bound through borate groups. For all considered glasses the niobium polyhedra does not form extended chains.
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A statistical analysis of the relationship of the redox ratio of the produced float glass with the technological mode of cooking, the charge content and the chemical composition of the glass was carried out. The influence of the redox ratio on the technical and economic performance of the bath furnace and the quality of the glass produced is shown.
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Transparent glass-ceramics are attracting more and more attention as a material for protecting the screens of electronic devices. The paper considers the possibility of carrying out ion-exchange of transparent gahnite glass-ceramics containing a small Na2O content. The structure and properties of glass-ceramics before and after ion-exchange were studied by x-ray diffraction analysis, transmission electron microscopy, Raman spectroscopy, laser-induced breakdown spectroscopy, and Vickers hardness determination. It is shown that, under certain conditions, ion-strengthening of glass ceramics with a low content of alkali ions can lead to an increase in microhardness values.
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Ceramics Ce0.9Bi0.1O2 – ? was obtained by solid-phase synthesis. It is shown that the obtained samples have a cubic fluorite structure with the space symmetry group Fm3m. The electrical properties of the Ce0.9Bi0.1O2 – ? solid solution were studied by ac impedance spectrometry. It has been established that the activation energy of electrical conductivity has two sections 0.51 eV (400 – 680 ?С) and 1.6 eV (680 – 800 ?С), the activation energy of the dielectric relaxation process was 0.88 eV.
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Lead-containing perovskite of complex composition PbNaKNb2FeO9.5 (sp. gr. Pnma, a = 5.654 ± 0.003 ?, b = 7.977 ± 0.001 ?, c = 5.646 ± 0.003 ?) was synthesized for the first time by the solid-phase reaction method. The sample is characterized by a non-porous microstructure formed by randomly oriented cubic crystallites. The band gap (?2.10 eV) of a complex perovskite for a direct allowed electronic transition was calculated from the data of the diffuse reflectance spectrum. The permittivity of the sample at room temperature and a frequency of 106 Hz reaches 1365, and the dielectric loss tangent is 0.1.
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Dispersion characteristics of the Zhuravliny Log kaolin, zeta potential, and apparent viscosity of its suspensions were studied. Kaolin suspensions had rather high stability due to the negative charge of particle surface. Zeta potential was described
as a function of pH and tripolyphosphate concentration by the electrophoresis. The additive influenced the apparent viscosity of suspensions for account of pH and zeta potential increase ability. Kaolin isoelectric point was found (3.28). Kaolin suspension had a sufficiently high casting rate that might be explained by a good mineral crystallinity (Hinkley index 1.76).
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Today, in the field of construction, the volume of use of ceramic paving stones is growing from year to year to improve the resistance to environmental influences and the decorative properties of road surfaces of modern buildings and structures. Along with this, it is important to obtain ceramic pavers based on compositions consisting of mineral and technogenic raw materials that prevent premature wear under the influence of a salty environment in regions with high salinity.
All over the world, intensive scientific research is being carried out to develop the production of ceramic paving stones and other related building materials for regions with high humidity and salinity. In research, special attention is paid to improving the process of firing ceramic mass, introducing modifying additives into the composition, developing technologies for obtaining new materials with crystalline structures and the formation of their properties.
