Кераміка: наука і життя

Journal Information
ISSN / EISSN : 25216694 / 25216708
Total articles ≅ 79
Filter:

Latest articles in this journal

M.T. Dovzhik
Кераміка: наука і життя pp 18-22; doi:10.26909/csl.2.2019.3

Abstract:The process of mixing the components of the mixture is an important factor affecting the physical and mechanical properties and appearance of the final product. The proposed designs of vibroexcluders for mixing fibrous concrete and the formation of flat products provided analytical formulas for calculating the process of vibration extrusion. The quantitative criterion of laminar convective mixing, which occurs when vibroexclusion, is the degree of increase in the surface area of the interface between the components, which in turn depends on the total deformation and initial orientation of the surface. The constructions of vibroextruders are provided for the mixing of a fibrous concrete and forming flat products, and analytical formulas are given for the calculation of the vibroextrusion process. The construction of a cascade vibrating extruder for the proposed mixing can be applied to a wide range of compositions of fibro concrete mixes, and a specially designed vibratory extruder for forming can significantly improve the longitudinal orientation of dispersed fittings in flat products. The degree of longitudinal orientation of the fiber in the process of vibroexclusion of fiber concrete can be regulated by the geometry and size of the channels of the vibroexcutter bunker, as well as by the application of special guiding partitions. Practically the degree of mixing is characterized by the speed of vibration exclusion. Due to the fact that the vibroextrusion mixing does not occur the destruction of fiber reinforcement, as a result of the successive passage of the mixture through several channels, the moment when the vibration excursion velocity stabilizes. The given analytical dependencies give the possibility of quantitative description of differences in the deformation of the mixture and the final orientation of fibers in the products for the proposed apparatus. The degree of longitudinal orientation fibers need to be set separately for different products, depending on their purpose, and change the degree of orientation is carried out by changing the geometry of the vane bunker vibroextruder. The results of the work are supposed to be used in the design of a new vibration excretory equipment for mixing fibrous concrete mixtures and the formation of dispersed reinforced products.
Ye.Ya. Telnikov, O.G. Chernyshyn, O.M. Nedbailo, I.O. Khmara
Кераміка: наука і життя pp 23-28; doi:10.26909/csl.2.2019.4

Abstract:The work is devoted to the solution of scientific and technical problems of creating granular resistive thick films used in the manufacture of metal-ceramic heating elements. Using the method of mechanosynthesis, particles of transition metal borides and aluminoborosilicate glass of complex chemical composition were obtained. The electrical and thermal properties of thick-film metal-ceramic heating elements with a resistive layer based on modified particles of a conductive material are studied. The heating elements of the new generation are made by the method of thick-film technology, which is widely used in microelectronics in the manufacture of hybrid electronic circuits. Structurally, the thick-film heater is a base (metal with a dielectric coating, ceramics, glass, glass), which is consistently applied through a mesh stencil resistive paste and a dielectric protective coating. Direct heat transfer from the heating film to the substrate of the heat remover, due to the very low thermal inertia of the design, provides a quick exit of the heating element to the operating temperature. This feature of heaters opens new opportunities for their special use. The resistive layer is a complex heterogeneous disordered system containing regions with a metallic conductivity and dielectric portions. The electrical conductivity in such systems is a superposition of the metallic type — in the conducting phase and the activation phase — through the interlayer between the particles. The layer plays the role of a potential barrier for current carriers and largely determines the predominance of one of the electromigration mechanisms. Its composition and properties are formed during the interaction of molten glass with oxide films of particles of the conductive phase and doping of the compositions. Obtaining composite particles of the conductive phase in the process of preparation and heat treatment of materials allows you to purposefully change the properties of the nanoscale interlayer between these particles, which leads to the possibility of creating a group of materials and heating elements based on them with a complex of new properties.
Yu.G. Gasan, V.I. Tarasevich, V.B. Dolgoshey
Кераміка: наука і життя pp 15-17; doi:10.26909/csl.2.2019.2

Abstract:By spent researches is established, that the products from a composite material on a basis gypsum and sulfur do not include in the structure potentially dangerous for organism of the person and environment of connections of mercury, thallium, selenium, arsenic; are chemically stable and do not allocate in inducing air, water and acid of environment unstable of inorganic connections. By manufacture of products on air environment of a working zone can be allocated hydrogen sulphide and sulphureous anhydride, that requires the appropriate organization of labour of the workers with maintenance of a premise by compulsory ventilation and measures of fire-prevention safety. Toxicological and hygienic studies of powdered sulfur gypsum material in case of cutaneous admission (50% vaseline emulsion) allowed to establish the following: after the first application of the paste, no visible changes were observed on the skin of animals. After ten applications in 2/3 of the experimental animals, pale pink erythema was observed throughout the paste application area. With further applications, the intensity of skin hyperemia did not increase. The resulting changes can be classified as a moderately pronounced skin irritating effect of powdered sulfur gypsum material. Analysis of the information obtained during the formulation of basophil degranulation reactions and specific agglomeration of blood leukocytes of guinea pigs sensitized with powdered sulfur gypsum material indicates the absence of statistically significant changes in the parameters of the studied reactions in animals of the experimental and control groups. This gives grounds for concluding that sulfur gypsum materials do not possess allergenic activity. Based on the conclusion of the Chief Sanitary Doctor of Ukraine, a composite material based on gypsum and sulfur is recommended for the manufacture of tiles that can be used in the construction of buildings of “B” and “V” groups (industrial and public buildings).
Zh.O. Petrova, B.V. Davydenko, K.S. Slobodianiuk
Кераміка: наука і життя pp 7-14; doi:10.26909/csl.2.2019.1

Abstract:The process of drying is an energy-consuming process, therefore, in order to optimize these energy costs during drying and to choose the rational structural and regime parameters of the equipment intended for this process, it is necessary to carry out a calculation analysis of heat and mass transfer on the basis of adequate mathematical models. The study of various mechanisms of diffusion in capillary - porous materials has become the basis for the creation of a mathematical model of heat - mass transfer and for the formulation of a corresponding system of nonlinear differential equations. Using mathematical model of heat-mass transfer A.V. Lykova constructed an appropriate numerical algorithm for modeling this process, numerical studies of the convection drying process of colloidal capillary - porous materials (KKPM) have been performed. The boundary conditions on the contact surface of the material in the drying chamber with the heat carrier flow are formulated. Based on the numerical solution of the system of one-dimensional heat and mass transfer equations in the material, depending on the time of its specific moisture content and temperature, as well as other characteristics of the convection drying process, the dependence was obtained. The estimated results are compared with the results of experimental studies. From the results of the comparison, it follows that the calculated model on the basis of the proposed system of equations satisfactorily describes the process of mass transfer in colloidal capillary - porous materials and can be used to approximate the characteristics of the drying process of colloidal capillary - porous materials, in particular the time required for drying the material. Numerical modeling of heat and mass transfer processes in colloid capillary and porous materials helps to solve an important scientific and technical problem, which is connected with the creation of software and hardware complexes, automated systems of scientific researches of energy-saving heat-technological processes of drying of materials with the provision of necessary quality indicators. Having analyzed the literature data concerning the existing developed mathematical modeling of colloidal capillary-porous materials, it has been established that this direction has a limited amount of information and therefore requires in-depth study and is an actual direction of research.
O.O. Titova, L.P. Chernyak, L.A. Nudchenko
Кераміка: наука і життя pp 7-12; doi:10.26909/csl.1.2019.1

Abstract:Thanks to the peculiarities of the chemical composition and structure, perlite has received application for manufacturing building materials - thermal insulation and ceramic Results over of research of the silicate systems with transcarpathian perlite as raw material for making of mineral astringent material are driven. The features of the chemical-mineralogical composition, phase transformations during burning and astringent properties of material at the use of perlite from Beregovsky deposit in composition initial raw material mixtures are shown. To determine and optimize raw material stock at the production of mineral binder material of low-temperature roasting type of natural or romanticum, a computer program "RomanCem" was used. After burning with a maximum temperature of 1100°C, the test of the binder material from the investigated 3-component mixtures with Transcarpathian perlite is characterized by differences in phase composition and properties. When using for the manufacture of mineral binder material of low-temperature firing of a gypsum natural or romantic cement 3-component mixtures based on the limestone system - perlit - clay, the content of Transcarpathian perlite is possible from 4 to 22 mass. %.
A.V. Timoshchenko, Ye.V. Timoshchenko, O.V. Hyliienko, I.P. Bieliaieva
Кераміка: наука і життя pp 13-19; doi:10.26909/csl.1.2019.2

Abstract:The manuscript presents the results of the research of the kinetics of radiation drying of basalt-bentonite cardboard. It has been established that in the case of high-temperature radiation drying of cardboard, the value of the reduced first critical moisture content in the area with low values – 0.17 is observed; compared to the same indicator for convective drying of slabs 50 and 100 mm thick - 0.41 and 0.20, respectively. This feature of the process allows you to raise the temperature in the first drying chamber to 570-600°C without fear of local overheating of the material. It was noted that at the stage of the falling drying speed, which is largely implemented in the second drying chamber, in order to avoid local overheating of the material, the temperature in the chamber is limited to 440°C. The decrease in the temperature level of the process in the second drying chamber is compensated for by the active gas-dynamic environment, in which the average speed of the drying agent in the inlet action zone can reach values of ± 5 m/s. The results of the controlled operation of the pilot conveyor drying installation are given. Its satisfactory specific energy indicators are noted, which for the same type of installations can reach values of 1200-2000 kcal/kg of moisture. In conclusion, it is noted that, in addition to the traditional positions of the heat balance of the plant, an energy-efficient modernization of a conveyor drying plant should include reducing losses with a spent drying agent, with recuperative losses through walling structures, with unorganized gas exchange in the drying chamber, and such positions as efficient drying agent with the optimization of its gas dynamics in the drying chamber.
Yu.F. Snezhkin, V.м. Paziuk, Zh.O. Petrova
Кераміка: наука і життя pp 20-25; doi:10.26909/csl.1.2019.3

Abstract:The mathematical processing of experimental data obtained during the drying of spherical form of capillary-porous materials on a convective drying bench allows us to determine the influence of various factors on the process. The main factors influencing the kinetics of drying of capillary-porous materials of spherical shape are the temperature and velocity of the heat carrier, as well as the initial moisture content of the material. For each factor, the variation levels corresponding to the optimal conditions for conducting experimental studies with low-temperature drying conditions are recommended. For a mathematical description of the duration of drying of capillary-porous materials, we use an orthogonal composite plan of the second order. As a result, the proposed mathematical model of the process obtained regression equations and the response surface of the duration of drying of capillary-porous materials of spherical shape. The obtained regression equations of the drying time give a detailed description of the influence of both individual and joint actions of factors, the significance of these parameters is determined by the corresponding coefficients according to Student's criterion. Also, the adequacy of the mathematical model according to Fisher's criterion, which corresponds to the real object, is checked. The construction of the response surfaces of the drying time of capillary-porous materials indicates the nature of the effect of these factors in the given range of variation.
Ye.Ya. Telnikov, I.O. Khmara, O.M. Nedbailo, O.G. Chernyshyn
Кераміка: наука і життя pp 26-31; doi:10.26909/csl.1.2019.4

Abstract:The results of the study of the electrophysical properties of metal-ceramic compositions based on nickel boride depending on the composition, heat treatment conditions and after exposure to mixed reactor radiation (neutrons and γ-radiation) are presented. A method of metallization of piezoelectric ceramics based on materials developed using thick-film technology is proposed. The paper discusses the results of the study of physicochemical processes occurring during the heat treatment of films and their influence on the properties of piezoceramics. The advantages of thick-film technology, widely used in microelectronics, are well known, but the use of noble metals causes a number of serious production problems associated with their high cost, the need for waste management and reporting; Operational disadvantages include instability of properties (especially under mixed reactor irradiation conditions) due to the high diffusion coefficients of these metals (especially silver) and their leaching when soldering the leads. This work is devoted to the study of the electrophysical properties of pastes for thick-film metallization of piezoceramics, which do not contain extremely scarce and noble metals, burned in air, are not inferior in their operational parameters to pastes based on silver-palladium alloy and are intended to replace the latter.
O.M. Nedbailo, O.G. Chernyshyn
Кераміка: наука і життя pp 29-31; doi:10.26909/csl.4.2018.4

Abstract:In article the technique of definition factors of carrying over weight of substance in the course of roasting ceramic materials which is based on exponent dependences of change mass bodies from time of its heating is offered. The process of firing ceramic materials is associated with the transfer of heat and mass of matter. Therefore, for a more complete calculation of the heat treatment mode, it is necessary to know the conditions for the mass transfer in the product being calcined. The aim of the work is to determine the mass transfer coefficients of the substance in the process of firing ceramic materials. The mass loss rate of the bound matter or the mass loss per unit time will be directly proportional to the average mass content of the body. On the other hand, the mass loss rate of the bound matter is numerically equal to the slope of the mass content kinetics curve. Proposed in the work formulas can be applied when studying the process of mass transfer during firing of samples from different clays, as when firing clay samples of different diameters under the same conditions, they will differ in the mass content (mass loss rate of the bound substance) during heating and their final relative amount (mass content) of the lost mass will be the same.
V.O. Kremnev, L.U. Shpilberg, A.V. Timoshchenko, O.V. Hylienko, Ye.V. Timoshchenko
Кераміка: наука і життя pp 21-28; doi:10.26909/csl.4.2018.3

Abstract:A brief historical overview of the creation of technology of the materials based on staple basalt fibers is given. The primary role in creating the technology of the Institute for Problems of Materials Science of the National Academy of Sciences of Ukraine, a number of academic and sectoral institutes is noted. Thermophysical characteristics of basalt fibrous materials and basalt-bentonite products are given. For fibrous materials based on BSTF, the following dependences are given: thermal conductivity coefficient, as a function of density and temperature; optimal density of the heat insulating canvas, characterized by a minimum coefficient of thermal conductivity, as a function of temperature; the compaction factor of the canvas, as a function of temperature. The description of the multistage duplex process of the BSTF production is given. The block diagrams of the production processes for soft and semi-rigid products are considered. The stages of production at which natural gas is consumed are highlighted. A high proportion of the cost of energy in the cost of finished products reaches 70 - 80% is given. The results of experimental-industrial tests of the main gas-using equipment - melting furnaces, gas burners, tunnel dryer are given. Two methods were used to determine specific energy consumption. The maximum of the values determined by different methods was chosen as the defining value of energy consumption. There is a non-stationary nature of the equipment. The results of the analysis are presented in the form of specific indicators of natural gas consumption per unit of finished product, and heat per 1 kg of evaporated moisture. Thus, the specific consumption of natural gas per 1 kg of BSTF, for the existing technology, is 4,8 standard cubic meter, and the release of 1 cubic meters basalto-bentonite plate - 300 standard cubic meter. The basic heat engineering principles are formulated, which will allow a multiple increase in the energy efficiency of heat technologies, among them - the reduction of losses through the structures of equipment; loss reduction with high-temperature combustion products; intensification of heat and mass transfer processes in equipment components and elimination of unorganized gas exchange of internal technological volumes.