Кераміка: наука і життя

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ISSN / EISSN : 25216694 / 25216708
Total articles ≅ 96
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O.M. Fesenko, V.V. Korskanov, V.B. 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.
V.V. Glukhovskyi
Кераміка: наука і життя pp 7-12; doi:10.26909/csl.1.2020.1

Abstract:
The mechanism of contact-condensation solidification provides the formation of a solid rocky body in the event of contact between the microparticles of a substance of amorphous or unstable crystalline structure without changing its chemical composition as a result of physical surface phenomena. Therefore, to provide stronger contacts between the particles of such binders during their condensation, it is necessary to apply external pressure (compression). The implementation of such binders is not linked to the timing of grieving. The curing process is carried out immediately at the time of contact between the particles of such binders. In the future, the strength of artificial stone increases in natural conditions and in water. The results of studies of the dependence of the pressing parameters on the basic performance of the products based on the binder contact-condensation hardening are presented. It is established that in order to maximize the effective action of pressures, which provide plastic deformation during compaction and provide the most dense packing of powder particles, there is a limit of working pressures in the range from 40 to 150 MPa. It is shown that it is convenient to use mathematical expressions (extrusion equations) when analyzing the processes occurring during extrusion, which reveal a functional relationship between the pressure and the density of the material thus obtained. With the help of the equations of pressing, for each powder or group related to the physicochemical parameters of the powders, the most economical parameters of the pressing modes can be determined. The data obtained for the compression pressure characterizing the action of plastic deformation for the test mixtures is in the pressure range from 32 MPa to 158 MPa. Increasing the pressure above leads to the transition of plastic deformation into elastic deformation, in which the seal passes due to the destruction of particles under the action of high pressures.
Ye.Ya. Telnikov, O.G. Chernyshyn
Кераміка: наука і життя pp 13-17; doi:10.26909/csl.1.2020.2

Abstract:
The article deals with the technical parameters of thick-film heating elements, the peculiarities of their operation, as well as the scope of use in household and industrial heat-generating electrical devices. The world is constantly researching the possibility of developing heating elements without the aforementioned disadvantages of tube thermal elements, which allow more efficient use of consumed electricity, which leads to significant savings. A new type of heat to heat converter is proposed in this direction. The use of this converter - the heating element - in various industrial and household products can save up to 30% of electricity consumption. At the heart of the design of the heating element is a developed system of different properties of composite nanostructured materials - pastes. On the basis of this system of materials the technology of production of new heating elements with unique properties was created. The heating element is made by screen printing (silk screening) of special composite materials on a dielectric or metal substrate with their subsequent heat treatment. Dielectric, resistive, dielectric layers are sequentially applied to a flat substrate of any configuration, but can also be applied to cylindrical surfaces. Purposeful formation of a conductive structure in the resistive layers of thick-film heating elements and the ability to influence the properties of the nanoscale layer between the particles of the conductive phase allowed to create a group of materials, and on their basis, a series of heating elements with the properties of the technical intellect, environment. The technology for production of heating elements with self-regulation of parameters for wide values of supply voltage, thermal power, and specific heat dissipation power (surface heat flux density) has been developed. One of the significant advantages of the technology is the absence in the resistive paste of expensive and scarce precious metals and their compounds, which are part of similar pastes, offered by leading manufacturers in the world. Due to this, the cost of manufacturing such pastes is substantially lower than that of the world.
L.P. Shchukina, S.L. Lihezin, M.I. 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.
Gennadiy Voronov, Oleksiy Fesenko, Oksana Savvova, S.O. Melnyk, O.P. Dehurko
Кераміка: наука і життя pp 7-13; doi:10.26909/csl.4.2019.1

Abstract:
The article presents the results of a study of stone processing waste in order to justify the implementation of the technological process of manufacturing architectural and construction products with their use. The structure of the distribution of waste arising from stone processing processes is given. The analysis of the relevance of the problems of utilization of slurry waste stone processing. Studies were conducted to determine the chemical, mineralogical and phase composition of stone waste. It was found that these wastes belong to gabbro-diabase rocks, which was confirmed by their chemical and mineralogical composition. The main mineral components are plagioclase, pyroxene and minerals of the iron group. The moisture content of the initial pulp and the particle size distribution of dry sludge were determined. Based on the results of establishing the melting temperature and fire resistance of baked sludge samples, the possibility of obtaining architectural and construction products based on dry sludge using ceramic technology (semi-dry pressing and sintering) was established, for which a selection of technological parameters and initial mass compositions was carried out. The promising compositions of ceramic masses with a significant sludge content (up to 60%), as well as the temperature-time regimes of the formation of ceramic materials, which are in the range from 1100 to 1200°C, are determined. The physicomechanical properties for sintered ceramic materials are studied, namely, mechanical strength compression (up to 55 MPa) and wear resistance (up to 0,45%), which corresponds to the properties of clinker ceramic materials. Based on the foregoing, a conclusion was drawn on the prospects of using stone slurry for obtaining ceramic products for architectural and construction purposes.
V.V. Korskanov, O.M. Fesenko, T.V. Tsebrienko, O.P. Budnik, V.B. Dolgoshey
Кераміка: наука і життя pp 14-20; doi:10.26909/csl.4.2019.2

Abstract:
The objects of study were water dispersions of raw graphene (hereinafter referred to as graphene-n), higher degree of purification of graphene samples (hereinafter graphene), and nanoparticles of graphene-Au nanoparticles based on them. The thermal conductivity of water graphene dispersions and water dispersions of gold graphene nanoparticles nanostructures at different temperatures and component ratios was investigated. The values ​​of effective thermal conductivity of dry nanofillers are calculated. The temperature dependences of the thermal conductivity of the nanofillers were obtained. It is found that the in-thermal conductivity of water dispersions of purified graphene is higher than the thermal conductivity of raw graphene as a result of better packing of nanoparticles in pure graphene nanofillers compared to raw. The effect of enhancement of thermal conductivity of gold nanoparticles, which is accompanied by higher absolute values of thermal conductivity of nanoparticles of graphene-nanoparticles of gold than the corresponding graphene, was revealed. At the same time, there is a significant difference in thermal conductivity between nanoparticles of graphene nanoparticles of gold. It is established that higher values of thermal conductivity of graphene-nanoparticles nanostructures of gold are the result of the reinforcing action of a gold nanoparticle substrate, which is formed as a result of joint sedimentation with graphene during the formation of nano-flakes from water solution during evaporation of water.
V.V. Glukhovskyi
Кераміка: наука і життя pp 26-30; doi:10.26909/csl.4.2019.4

Abstract:
The results of scientific research in realization of energy-intensity cellular concrete production technology of normal condition hardening are shown. Physical-mechanical and thermophysical properties of cellular concretes, which are produced by this technology, are relevant to active normative documents. In this case the produced cellular concretes are characterized with strength increasing in time in compare to autoclave hardening cellular concretes and aerated concrete. The influence of the chemical activity of the fillers on the performance of the final product has been established. According to the results of the performed researches it is established that the activity of the filler determines the kinetics of change in the time of the strength of the composition, which solidifies under normal conditions. When used as ground coal ash filler, the level of strength of porous concrete at the age of 28 days is at the level of strength of the composition with the addition of ground granulated slag (3,22 and 3,38 MPa, respectively). It is also found that, unlike autoclaved aerated concretes, the strength of aerated concretes of normal cement based on Portland cement increases over time both on binder without mineral additives and in the presence of ash, milled slag and quartz sand. The intensity of the process of gaining strength over time is determined by the activity of the mineral additive. When used as a mineral admixture of non-ground quartz sand, which, under normal curing conditions, does not interact with the curing of Portland cement, the strength of the porous concrete decreases with increasing amount of this additive in the composition. The intensity of the strength of these compositions at the age of 90 days, depending on the amount of additive, is 10 - 18%. The proposed technology for the production of cellular concrete based on Portland cement, curing under normal conditions, was implemented in industrial production. D700 concrete was selected as the base for production.
V.V. Korskanov, O.M. Fesenko, P.P. Pogoretskiy, O.P. Budnik, V.B. Dolgoshey
Кераміка: наука і життя pp 31-41; doi:10.26909/csl.4.2019.5

Abstract:
Today, Ukraine has retained a fairly strong scientific potential. However, the level of patent and innovation activity in Ukraine is low, because the state provides for a small percentage of the gross domestic product (GDP) that goes to finance research. In recent years, the number of research works and staff of research institutes has been shrinking rapidly due to chronic underfunding and outdated experimental research equipment. For the same reason, the citation index of works of Ukrainian scientists is low. The weak material base of the Ukrainian research institutes stipulates that the ratio of experimental to theoretical scientific and technical developments has been decreasing in recent years. Most patents are registered by Ukrainian scientists in Ukraine - in Ukrpatent. The majority of international patents are granted to Ukrainians in the USA, Germany and Switzerland. Against the background of the integration of Ukrainian scientists into the world community, there is a significant increase in the number of joint scientific publications of Ukrainian scientists with foreign colleagues. In recent years, the world has seen a rapid increase in patents on nanotechnology in the most technologically advanced countries in the world. The patent and innovation activity in Ukraine is expected to grow rapidly in the near future. The main goal is to ensure rapid and qualitative transformation of creative ideas into innovative products and services that increase the level of innovation of the national economy.
Zhanna Petrova, V.M. Vyshnievskyi, Yu.P. Novikova, A.I. Petrov
Кераміка: наука і життя pp 21-25; doi:10.26909/csl.4.2019.3

Abstract:
The technology of drying colloidal capillary-porous materials to a final humidity of 6-8%, developed at the Institute of Technical Thermophysics of the NAS of Ukraine, allowed to obtain a brittle state, in which it is possible to grind this product to small particles. The most suitable for industrial grinding of the dried composite colloidal capillary-porous materials is the impact method, because when wiping and crushing the material has accumulated, stuck to the working surface. Powders are characterized by one pronounced maximum corresponding to the particle size of the powder of 0,16 mm. As the rotation speed of the shredder rotor changes, the particle size distribution of 0,16 mm increases by reducing the larger particles. The amount of powder thus obtained is directly proportional to the speed of rotation of the rotor. The study of the dispersion and classification of functional powders showed that all powders have the largest particle size of 0,16 mm. The maximum yield of this fraction is 70% and the lowest is 40%. The structural-mechanical characteristics of powders from composite colloidal capillary-porous materials were investigated for the first time. Characteristics of different fractions were determined by such parameters as bulk density, vibration density, angle of natural slope, speed of material flow through the funnel and others. Studies to determine the structural and mechanical properties of functional powders have shown that they can be attributed to more bulk powders, as opposed to highly bound monopowders. Creating compositions improves their structural and mechanical properties.
K.V. Kirilenko
Кераміка: наука і життя pp 23-29; doi:10.26909/csl.3.2019.3

Abstract:
In the context of rising energy costs and the need to use new energy sources, works aimed at raising the surface temperature of heat radiators with reduced energy consumption are of particular importance, and it is especially important if these processes are also accompanied by the effects of self-stabilization. Bulk materials do not possess these properties. However, materials whose dielectric matrix is also an active element can provide up to 10 - 30% of the thermal energy that will be released in the material, thereby increasing the surface temperature and without increasing energy consumption. Therefore, the study of composite materials with different matrices is relevant. This article the influence of the matrix material on the electrical properties of composite materials was examined. It was established that the microstructure morphology of resistive materials changes significantly depending on the matrix type. In composites based on matrix AlN, for the entire range of concentrations HfC, conducting cluster is formed with a metallic conductivity. For composite systems Al2O3-HfC and Si3N4-HfC thermoactivated hopping conduction between nearest neighboring states observed. Thus, for materials based on Si3N4 matrix at temperatures up to 300°C observed reduction of charge carriers concentration with increasing temperature. The approximation of the temperature dependence of the electrical conductivity was carried out on the basis of the following possible variants of the nature of the electrical conductivity, namely: jump conductivity (nonlocalized states, localized states in the tails of conduction and valence bands, localized states near the Fermi level), tunneling. It can be assumed that the formation of conductive clusters occurred under the influence of two factors: magnetic field and mechanical loading. When using the AlN matrix, the influence of the magnetic field on the structure formation is smallest. This conclusion can be drawn from the fact that the formed conductive clusters have the appearance of a linear chain structure.