Кераміка: наука і життя

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ISSN / EISSN : 2521-6694 / 2521-6708
Total articles ≅ 104
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V.V. Sobchenko, V.A. Zhaivoronok, H.O. Sobchenko
Кераміка: наука і життя pp 18-22; doi:10.26909/csl.3.2020.3

Abstract:
The possibility of obtaining perspective geopolymer materials for use in the building industry was shown. Geopolymer materials are used with such advantages as high strength, density, water resistance, heat and heat resistance, environmental friendliness, durability, and high corrosion resistance. The raw material is rottenstone, a rock with a high silica content, which is widespread in Ukraine. Rottenstone is characterized by a ratio of SiО2:Al2O3 equal to 16… 20, which provides a high strength of the final material. It was indicated that physico-chemical processes that take place during polymerization are similar to those that take place in thin pellicles of the released SiO2 gel, cements the particles, and thus promotes hardening. As a result of the treatment of raw materials with alkali solution at temperatures of 80-120 °С, a monolithic solid material of olive color with a density of 1200-1700 kg/m3, humidity of 30-45% was formed. Precipitations were observed on the surface of the material due to the presence of non-chemically bound sodium and potassium cations in the pores of the geopolymer. When dried, they diffuse to the surface of the geopolymer and are subjected to atmospheric carbonization. It was indicated that in order to obtain a high-strength geopolymer material, it is necessary to carry out final heat treatment at temperatures close to 100 °С. The behavior of geopolymer samples aged over time at room temperature during their heating was investigated. The samples of the material are melted due to the presence of Na2O×SiО2×8Н2O and Na2O×SiО2×5Н2O crystal hydrates, which melt at relatively low temperatures at 48°С and 72°С, respectively. The formation of building geopolymer materials should take into account this melting by placing it in molds was concluded. Indicators of moisture loss at a temperature of about 100°С depending on the heat treatment time were obtained.
O.M. Nedbailo, O.G. Chernyshyn
Кераміка: наука і життя pp 23-28; doi:10.26909/csl.3.2020.4

Abstract:
Some aspects of resource saving problem in the process of construction of heated construction installations are considered in the paper, also heat transfer problem in porouse concrete. Is paid attention to necessity of application with mass construction of habitation of products from porouse concrete, first of all - products from of cellular concrete. In article the basic requirements of the standard documents regulating constructive properties of various building materials, including various concrete are analysed. The design a warm wall on the basis of products from porous concrete is considered. Its advantages in comparison with known designs of warm walls are shown. In article changes of technological properties of various building materials are considered at influence on them of a moisture. The analysis of the standard-regulating documents, concerning operational qualities, concerning reliability and durability of designs is carried out. The basic technical properties gas-concrete non-autoclave solidification on the basis of a waste stone machining are analysed. Results of researches technology indicators cement cellular concrete non-autoclave solidification with offered filling material are resulted.
L.I. Melnyk, L.P. Chernyak , O.V. Kozlovets
Кераміка: наука і життя pp 13-17; doi:10.26909/csl.3.2020.2

Abstract:
Composite materials for various purposes are made on the basis of initial mixtures of fillers and bonding components. The varieties of these components and their quantitative ratio determine the qualitative indicators of the composite. This causes rosettes of the raw material base for the production of composites, including the use of by-products of mineral extraction, which meets the objectives of resource saving. This paper presents the results of the study of composite materials on the basis of by-products of extraction of igneous rocks of Transcarpathia - siftings of andesite as a filler and copolymer Latex 2012 as a matrix. The analysis of chemical and mineralogical composition of andesite siftings from Khust quarry was carried out. An analysis of the dependence of the main physical and mechanical characteristics of the studied composites on the concentration of andesite in the range of 55-85 wt. % and of the corresponding change in the quantitative ratio of filler and copolymer is performed. Differences in parameters using andesite samples with different particle size distribution (the poly-fractional with particle size ˂ 3 mm and the dispersion one with particle size ˂ 0.5 mm) were determined. The peculiarities of the formation of the pore structure of the composite material obtained using andesite samples of different granulometry connected with the increasing degree of dispersion associated with the increase in the number of filler particles in the composite, increasing adhesion forces in the copolymer-filler system and increasing of surface energy of andesite particles are shown. The possibility of increasing the abrasive resistance of the composite material when using the initial mixture based on the andesite-copolymer system has been experimentally confirmed.
Yu.F. Snezhkin, V.м. Paziuk, Zh.O. Petrova
Кераміка: наука і життя pp 7-12; doi:10.26909/csl.3.2020.1

Abstract:
Heat pump technologies have become widely used in space heating and air conditioning systems, and the heat pump can be used for low-temperature drying of capillary-porous materials. Recuperative and condensing heat pumps, which allow both drying and cooling of the material, have become the most widespread. The developed condensing heat pump drying unit with a mine chamber implements a low-temperature drying process of spherical capillary-porous materials at a drying agent temperature of 40-50°C with a decrease in material humidity by 11% to a final humidity of 8%. Experimental studies on a heat pump drying unit for drying capillary-porous materials of spherical shape indicated a significant reduction in average energy costs per process up to 3700 - 4100 kJ/kg of evaporated moisture. The increase in energy consumption increases significantly in the second part of the second period, where heat consumption can reach 5000 - 5350 kJ/kg of evaporated moisture. The use of condensing heat pumps for low-temperature drying of capillary-porous materials has shown high energy efficiency compared to existing drying technologies.
O.Ur. Bilousov, V.A. Sviderskyy, O.V. Myronuk
Кераміка: наука і життя pp 15-20; doi:10.26909/csl.2.2020.2

Abstract:
The results of research of porous materials on the basis of products of ceramic production - chamot as a fractionating filler are given.. The features of formation of structure of material at the use of chamot with different chemical and mineralogical compositions in the conditions of speed baking are shown. Porous ceramics for filtration and aeration is obtained by a technology based on the regulation of porosity parameters by the use of chamotte of a certain granulometric composition and special binders. However, the granulometric composition of chamotte is a necessary but not sufficient factor to optimize the properties of porous filter ceramics. Along with the granulometry of chamotte, its chemical and mineralogical composition and surface energy must be taken into account. It depends in turn on the technological properties and the firing parameters of the original clay raw material. This paper presents the results of a study of porous materials based on ceramic products - chamotte as a fractionated filler. The chemical and mineralogical composition of chamotte made of poly-mineral clay at maximum firing temperature of 950°С and of refractory clay at firing at 1320°C was analyzed. The energy state of the surface of the chamotte particles was determined with the wetting by polar and non-polar liquids (water and benzene respectively). The differences in the specific effective surface area, lyophilicity and filtration coefficients was determined. The peculiarities of the formation of the pore structure of ceramics obtained using the specified samples of chamotte in the conditions of high-speed firing in the roller oven are shown. Significant differences in the formation of open and closed pores were observed, the predominant specific proportion of open pores in the material using polymineral clay. The possibility of properties regulation of the pore structure and the energy state of the surface of the filter material when applying a mixture of chamotte varieties was experimentally confirmed.
S.A. Knyazev
Кераміка: наука і життя pp 26-30; doi:10.26909/csl.2.2020.4

Abstract:
The results of obtaining borated layers on 15H11MF high-alloy steel under equilibrium and non-equilibrium heating conditions are presented. Equilibrium conditions were achieved by slow furnace heating (with a heating rate of 0.1 oC/s), non-equilibrium – by induction heating (with a heating rate of 100 oC/s). The heating was controlled by measuring the thermoelectric power by a thermocouple welded to the surface of the sample by electric contact welding. The signal from the thermocouple was digitized by the ADC and transmitted to a computer where, at high speed, an array of data of temperature-time dependence of the process was formed. Furnace heating was carried out in a laboratory electric furnace at 1130 оС ± 5 оС, 1150 оС ± 5 оС and 1160 оС ± 5 оС. Induction heating was carried out to temperatures of 1180 oC ± 20oC, 1200 oC ± 20oC, 1220 oC ± 20oC. The possibility of significant reduction of the treatment process from 3 hours to 2 minutes due to the intensifying action in non-equilibrium conditions of structure formation is shown. Boron saturation came from the paste. Saturating paste consisted of 60% boron carbide, 30% NaF, 10% CaF2. The method of metallographic research shows not only the morphological differences of the obtained surface layers, but also established the predominant mechanism of boron diffusion into high-alloy martensitic steel. During furnace heating (1150оС), a solid boron with a thickness of up to 50 μm and a hardness of 15100 MPa is formed. At a depth of up to 150 μm, grain boundary diffusion is noticeable, which obviously dominates in the processes of boron saturation of high-alloy steels. At temperatures of 1160 oC and furnace heating under a solid layer of boride with a thickness of 110 μm, a two-phase zone is formed, which consists of boride and a solid solution with a thickness of 70 μm. This layer is more defective. Induction heating with boron saturation forms a thick (up to 200 μm) layer of coarse boride crystallites (18900 – 9270 MPa) with an eutectic structure (6440 MPa), which becomes coarser with increasing temperature from 1180 to 1220 оС. The ability to obtain solid hardened layers in a short treatment time makes boron saturation from pastes a more attractive alternative among other chemical-heat treatment technologies.
L.P. Chernyak , A. Soroka
Кераміка: наука і життя pp 21-25; doi:10.26909/csl.2.2020.3

Abstract:
The possibility of making of mineral astringent material of the low temperature «Mineral» computer program to determine the quantitative content of rock-forming minerals of silicate raw materials as factor in structure formation in technological processes of production and to achieve the specified properties of materials and products are shown. The results of calculations of the mineralogical composition of carbonate and clay raw materials are presented. Varieties of raw materials used in the chemical technology of silicates are a set of certain rock-forming minerals of known chemical composition. Determination of the quantitative content of rock-forming minerals of raw materials is possible by calculations based on the initial data of chemical and qualitative mineralogical compositions. The creation of a mathematical apparatus for processing the results of research and computer technology has increased the efficiency and efficiency of determining the quantitative content of rock-forming minerals. However, the constant increase in the number of varieties of potential raw materials makes it appropriate to improve the method of determining the quantitative mineralogical composition using computer calculations and modern software, in the direction of which the work is performed. Determining the quantitative mineralogical composition of raw materials using the computer program "Mineral" is appropriate to optimize the charge composition of masses and technological parameters of silicate production, including ceramics, glass and binders. The created program "Mineral" should be used by specialists of the building materials industry, production, research and design organizations working in the field of chemical technology of silicates, teachers and students of higher educational institutions.
V.V. Tsygoda, V.Ya. Petrovskiy
Кераміка: наука і життя pp 7-14; doi:10.26909/csl.2.2020.1

Abstract:
The possibility of reducing the thermal conductivity of silicon nitride as a basis of high-temperature electrical converters was investigated in the thesis. Also, the values of thermoelectric figure of merit and efficiency of thermoelectric current generator for the case of refractory oxygen-free composites were simulated. During the study, the dependence between the m coefficient, which determines the maximum possible efficiency of the thermoelectric generator and the ZT thermoelectric figure of merit, was determined. It was shown that the coefficient of thermal conductivity of the studied materials ranges from 1,2 to 4·106 m2/s and is characterized by a negative temperature coefficient over the entire temperature range. It was found that the thermal conductivity of Si3N4-based materials varies from 2,1 to 5,1 W/(m·K) depending on the type of sintering activator. The use of Al2O3 as an activator makes it possible to obtain a 25% lower thermal conductivity value comparing to materials with the addition of MgO. For the first time, it was proved that currently it is not possible to achieve an efficiency of 0,5hT in Si3N4-based materials used as a composite basis for high-temperature thermoelectric generators development.
O.M. Fesenko , V. V. Korskanov , Volodimir Dolgoshey , E.S. Kifuk, P.P. Pogoreckiy
Кераміка: наука і життя pp 24-28; doi:10.26909/csl.1.2020.4

Abstract:
The purpose of this work was to study the specific thermal conductivity of aqueous graphene dispersions and the diluted aqueous solution of nanostructures based on graphene and Au nanoparticles, as well as to determine the temperature and concentration dependences of the specific thermal conductivity of these aqueous dispersions. The objects of study were aqueous dispersions of graphene and nanostructures based on graphene and Au nanoparticles. Graphene has characteristic dimensions of the order of 150 - 200 nm in the plane. The Au nanoparticles also have an average size of about 50 nm and a star-like shape. In dry nanocomposites, graphene is oriented parallel to the substrate plane, and nanostars are evenly distributed on the sample surface. The specific volumetric thermal conductivity values of aqueous graphene dispersions and aqueous solutions of graphene-based nanoparticles and Au nanoparticles were obtained in the temperature range from 30оC to 60оC. A slight increase in the specific thermal conductivity was found with increasing temperature. The absolute values a/v of aqueous graphene dispersions are 1.6 times higher than in three-component systems. The concentration dependences of the thermal conductivity of the two systems studied are linear. It is determined that the values of the specific thermal conductivity of dry graphene nanofillers are 1,62 times higher than the thermal conductivity of a mixture of graphene and Au nanoparticles.
Liudmyla Shchukina, S.L. Lihezin, Mykhailo Ryshchenko
Кераміка: наука і життя pp 18-23; doi:10.26909/csl.1.2020.3

Abstract:
The efficiency of using different oxidizing agents to intensify the burnout of the organic component of ceramic masses is investigated. The ceramic masses contained coal flotation wastes with a high carbon content as a fuel-mineral additive. Various inorganic salts, which are oxygen donors during the firing of ceramic masses and form oxidizing agents O2, NO2, N2O during their thermal decomposition, are considered. A new calculation method for determining the content of an oxidizing salt in a ceramic mixture is proposed. This method takes as a basis the amount of «effective oxygen» that released during the thermal decomposition of the oxidizing agent, but not its mass, as it was before. The method allows calculating the rational content of an oxidizing agent necessary for efficient combustion of the carbon component of fuel-mineral additives. When calculating, it is necessary to take into the composition of the organic part of the additive, its content in the ceramic mass and the degree of carbon oxidation. Calculation of the rational content of the oxidizing agent according to this method allows avoiding its excessive and economically unreasonable use. The effect of oxidizing agents and their combinations on the burnout of the carbon component and the firing properties of the masses for wall ceramics is studied. The masses contained 15 % of coal flotation waste with a carbon content of 29 %. It was found that the use of oxidizing agents accelerates the burnout of the organic part of the masses, improves the appearance and mechanical properties of ceramic samples. The use of combined oxidizing agents with different decomposition temperatures makes it possible to create an oxidizing medium in a wider temperature range. This positively effects on the mechanical properties of ceramics. The optimal combinations of oxidizing agents NH4NO3+Ca(NO3)2 і NH4NO3+NaNO3, which made it possible to obtain ceramic samples with a compressive strength 10 МПа, were determined. This mechanical strength meets the requirements of the State Standard of Ukraine B M.2.7-61: 2008 in part of ordinary brick of the M100 brand.
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