Кафедра ливарного виробництва (ІПБТ)

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Complex of Mathematical Models and Methods to Calculate Pressure Effect on Sulfide Distribution in Steel
(Хмельницький національний університет, Україна, 2021) Selivyorstova, Tetjana V.; Selivyorstov, Vadim Yu.; Kuznecov, Vitaliy V.
ENG: Primary objective is to develop computational method to analyze digital pictures of sulfide prints, helping obtain qualitative image characteristics, and to formulate mathematical model of the distribution of sulphide inclusions to determine specific features of the pressure effect on the macrostructure formation of carbon steel castings flooded into the uncooled mold. The research was carried out using images of sulfide prints of templates cut of steel cylindrical castings; L500 steel was applied. The castings result from industrial tests of a method of gas-dynamic effect on the fusion in the foundry forms under the conditions of a casthouse of Dnipropetrovsk aggregate plant PJSC. Digital pictures of sulfide prints, obtained in terms of the increased rate of gas pressure and maximum pressure, were binarized; defective fra gments were removed; and zo ning took place. The developed computational method has been applied for fragments of images, representing different zones; data arrays have been received containing sizes and amounts of inclusions in the fragment. The developed computational method to analyze digital images of sulfide prints has been implemented. ASImprints software support has helped obtain qualitative characteristics of images; namely, distribution of amount of the certain-size sulfide inclusions. The computational method to analyze digital images of sulfide prints has made it possible to study the set of patterns of sulfide prints. The dependences have been obtained, describing specific features of sulfide inclusion distribution while varying gas-dynamic pressure method in terms of fusion in the casting form. It has been demonstrated that the distribution describes effectively the power-series distribution to compare with the exponential one. Mathematical model of the power -series distribution parameter dependence upon pressure has been developed. Deviation of the distribution parameters in terms of the experimental values and the model values has been evaluated. The research demonstrates the ways to apply an algorithm of simple recursive casting for quantitative analysis of digital images of sulfide prints. Use of ASImprints, being software implementation of the computational method to analyze digital images of sulfide prints making it possible to obtain qualitative characteristics of images, has helped identify that the increased pressure within a casting-device for gas injection system results in the increased specific amount of inclusions and the decreased specific zone of sulfide inclusions respectively. It has been defined that exponential function describes reliably the nature of sulfide inclusion distribution in the digital image of sulfide print. The research has demonstrated that fragments of a sulfide print, belonging to one zone, are statistically homogeneous. Thus, it is possible to analyze quantitively digital image zone of a sulfide print on its fragment. Mathematical model of dependence of sulfide inclusion distribution in carbon-steel castings in terms of gas-dynamic effect on fusion solidifying in a mold has been developed. The model may be applied to predict sulfide inclusion distribution within the selected zones of cross section of the cylindrical castings solidifying in the uncooled mold in terms of the preset mode of gas-dynamic effect.
Corrosion Resistance of Reinforced Layers of 15х11МФ Steel Steam Turbine Blades
(Національний науковий центр «Харкiвський фiзико-технiчний інститут», 2021) Hlushkova, D. B.; Bahrov, V. A.; Hrinchenko, O. D.; Hnatiuk, A. A.; Kalinina, N. E.; Kalinin, V. T.
ENG: The reliability of the vane apparatus of steam turbines largely determines the operation of the turbine as a whole. The results of scientific research indicate that the surface operation of the blades in the wet-steam flow is caused by a combination of corrosion and drip erosion. The presence of chemical elements and compounds in the working fluid intensifies the process of blade wear. The pH value of the working environment, which can fluctuate significantly during operation, has a significant effect on the wear characteristics. The influence of methods of strengthening the leading edges of steam turbine blades made of steel is analyzed 15H11MF on corrosion resistance. Corrosion tests of blade samples were carried out, the inlet edges of which were strengthened in three ways: high current amplification, electrospark alloying with T15K6 alloy, electrospark alloying with steel 15H11MF. According to the results of the tests, the layer strengthened by hardening by high-frequency currents has the lowest corrosion rate, the layer strengthened by electrospark alloying with T15K6 hard alloy has the highest. The corrosion rate of the layer reinforced by electrospark alloying of steel 15H11MF is 2.1 less than that of the layer reinforced with T15K6 alloy.
Determining the Thermally-Stressed State of Motor-Driven Bowls for Transporting Liquid Slag
(РС ТЕСHNOLOGY СЕNTЕR, Kharkiv, 2024) Povorotnii, Viktor V.; Shcherbyna, Iryna V.; Zdanevych, Serhiі V.; Diachenko, Nina K.; Kimstach, Tetiana V.; Solonenko, Lyudmila I.; Usenko, Ruslan V.
ENG: Slag bowls were chosen as the object of research, as important components of blast furnace, steelmaking, and ferroalloy shops of metallurgical enterprises. The main problem of operation of any slag trucks is their limited durability and frequent destruction of slag bowls. The reason for these problems is changes in the shape of the bowls during operation, manifested in the formation of narrowing places in the area of the support ring – for rail-mounted bowls, destruction of supporting pins – for rail-mounted slag trucks, or cracks in the walls. Those defects appear as a result of cyclic thermal effects of liquid slag on the bowl. Based on the results of computer simulation, it was established that the main role in the destruction of the support pins of motor-driven slag bowls belongs to temperature changes. The temperature stresses arising in the bowl are localized in the area of the slag mirror (200–250 MPa for 25L steel, 280–350 MPa for 30HML steel). The results provide grounds for improving the presented slag bowl to reduce temperature stresses in its walls and structures of the supporting trunnions. The results reported here are explained by the fact that with uneven heating of elastic bodies, temperature stresses appear, which, under certain configurations of temperature loads, lead to the destruction of structures. The findings from these studies are recommended to be used at enterprises for the design and manufacture of slag bowls, as information on the localization of dangerous places of the structure. In addition, the data presented here could be useful for metallurgical enterprises for detailed technical diagnosis of bowls in their dangerous places.
Efficient Algorithms for Parallelizing Tridiagonal Systems of Equations
(НМетАУ, Дніпро, 2021) Shvachych, Gennady Grygorovych; Vozna, Nataliіa; Ivashchenko, Olena Valerievna; Bilyi, Oleksandr; Moroz, Dmytro
ENG: The article is devoted to the development of the maximal parallel forms of mathematical models with a tridiagonal structure. The example of solving the Dirichlet and Neumann problems by the method of straight lines and the sweep method for the heat equation illustrates the direct fundamental features of constructing parallel algorithms. It is noted that the study of the heat and mass transfer processes is run through their numerical modeling based on modern computer technology. It is shown that with the multiprocessor computing systems’ development, there disappear the problems of increasing their peak performance. On the other hand, building such systems, as a rule, requires standard network technologies, mass-produced processors, and free software. The noted circumstances aim at solving the so-called big problems. It should be borne in mind that the classical approach to solving the tridiagonal structure models based on multiprocessor computing systems is far more time-consuming compared to single-processor computing facilities. That is explained by the recurrence relations that make the basis of classical methods. Therefore, the proposed studies are relevant and aim at the distributed algorithms development for solving applied problems. The proposed research aims to construct the maximal parallel forms of mathematical models with a tridiagonal structure. The paper proposes the schemes to implement parallelization algorithms for applied problems and their mapping to parallel computing systems. Parallelization of tridiagonal mathematical models by the method of straight lines and the sweeping method allows designing absolutely stable algorithms with the maximum parallel form and, therefore, the minimum possible time for their implementation on parallel computing devices. It is noteworthy that in the proposed algorithms, the computational errors of the input data are separated from the round-off errors inherent in a PC. The proposed approach can be used in various branches of metallurgical, thermal physics, economics, and ecology problems in the metallurgical industry.
Graphitizing Modification of the Axial Zone of Cast Iron Rolling Rolls in the Liquidus-Solidus Temperature Range
(Dnipro University of Technology, Dnipro, Ukraine, 2023) Khrychikov, Valerii E.; Meniailo, Helena V.; Semenov, O. D.; Aftandiliants, Y. G.; Gnyloskurenko, S. V.
ENG: Purpose. To develop a method for calculating a process of graphitizing modification of unsolidificated liquid-solid zone to reduce transcrystallinity of the macrostructure and the amount of cementite in the center of castings. Methodology. The duration of solidification of the castings was determined by the kinetic curves of liquidus, solidus and pouring boundary in coordinates of relative thickness of the solidified metal layer – the parametric criterion of Gulyaev. Findings. A methodology for the process of modification of the axial zone of rolling was developed, the mass and time of adding aluminum were determined according to the amount of liquid-solid phase that remains after the solidification of the working layer. On the example of a rolling roll weighing 1115 kg, 0.488 kg of aluminum was added into liquid-solid zone after the working layer solidified. Movement of aluminum to the front of crystallization is provided by centrifugal forces and adding of aluminum along the height of the roll. Originality. For the first time, the kinetic curves of liquidus, solidus and pouring boundary have been plotted in coordinates of the relative thickness of the solidified metal layer x/R and τ/R2 – the parametric criterion of Gulyaev for rolled cast iron alloys cooled in chill-sand molds of various sizes. A methodology was developed for calculating the process of aluminum modification of the axial zone of rolling rolls after solidification of the working layer in the barrel which was set at the pouring boundary. The amount of aluminum depends on the remains of the liquid-solid phase. Practical value. Graphitizing modification reduces transcrystallinity of the macrostructure and the amount of cementite in the axial zone of castings. A promising direction for further development is the development of new methods for manufacturing castings due to physical and mechanical effects on the two-phase zone, deoxidation and alloying of the central zones of castings.
Influence of Melt Properties on the Dendritic Structure of Steel Castings
(The Katowice Branch of the Polish Academy of Sciences, Poland, 2024) Aftandiliants, Y.; Gnyloskurenko, S.; Meniailo, Helena V.; Khrychikov, Valerii Ye.
ENG: The paper presents the experimental results on the determination of melt parameters such as the energy of the boundary, contact angle, density and kinematic viscosity of low and medium alloy steels at different temperatures, as well as the dispersion of their dendritic structure in solidified castings. The analysis of the data obtained allowed revealing using mathematical models the influence of the chemical composition and temperature of melts on their properties and the dendritic structure of castings. It was established the variation of the melt parameters depending on the particular chemical elements of steels as C, Si, Mn, O, P, V, Cr. The established analytical dependences shown that increasing density and viscosity contributes to the dispersion of the dendritic structure and viscosity is of the major effect. The derived quantitative patterns allows to evaluate structure formation of cast structural low and medium alloy steels.
Influence of Technological Factors on Formation Process of Bimetallic Castings
(Latvia University of Life Sciences and Technologies, Jelgava, 2023) Aftandiliants, Yevhenii; Gnyloskurenko, Svyatoslav; Meniailo, Helena V.; Khrychikov, Valerii Ye.
ENG: The analysis of the modern state of wear-resistant metallic material production showed that one of the promising directions for improving their quality is the use of bimetallic steel-cast iron castings, which have a complex of properties differentiated over the volume and surface of the products. However, the problem of obtaining a high-quality joint of the steel base and the working cast iron layers is not completely solved at present. So, the research aims to determine the quality criterion of a good diffusion joint and to study the selected technological factor influence on the formation process of bimetallic castings using the developed mathematical model. The paper examines the effect of the steel base temperature at liquid cast iron pouring over it, the temperature of pouring cast iron, as well as the ratio of liquid cast iron mass to the unit surface of the steel base on the contact surface temperature as selected quality criteria, and the structure of the transition diffusion layer of bimetallic castings. It was determined that a high-quality joint is realized when this temperature is larger than the solidus temperature of the cast iron. Moreover, the results of the mathematical model application showed maximum contribution of the liquid cast iron mass/steel unit surface ratio, less effect of the pouring iron temperature and minimum influence of the solidified steel base temperature onto the quality criteria. The metallographic analysis established the diffusion joint formation in the transition steel-cast iron layer consisting of pearlite on the side of the steel base and without the carbide matrix area on the side of the working iron layer. The results obtained are of great importance for the designing bimetallic machine parts worked under intensive wear conditions.
Intelligent Decision Support System
(RS Global Sp. z O.O., Poland, 2021) Shvachych, Gennady; Pobochij, Ivan; Sazonova, Maryna; Bilyi, Oleksandr; Moroz, Dmytro
ENG: Here one of the new efficient approaches to solving problems of intelligent support of making decisions of a cooperate enterprise scale is analyzed, bearing in mind that the enterprise is oriented towards integration of two interconnected information technologies: a technology of constructing information storages and a technology of intelligent data analysis. A new conception of the role of informating-controlling systems in controlling and operating pipe manufacturing process is suggested. It broadens a traditional view over information systems just as if it were only an instrument of a computer data analysis. The role of the modern information systems in the manufacturing as an independent scientific and applied direction serving as a connecting link in the triad “raw product – ngineering process – end product” is substantiated. Some problems connected with plantation of the informating-controlling systems in the pipe manufacturing is formulated. It broadens a traditional view over information systems just as if it were only an instrument of a computer data analysis. The practical application of this product permits the operating personnel of the enterprise to control the engineering process, analyze the processes passing in each mill, adjust the PRP mills’ engineering characteristics in the pipe-manufacturing process. The suggested approach influences quite strongly the production’s quality improving and enables to work stably in the thin-walled pipe grades sphere.
Kinetics of Quartz Sand and Its Mixtures Drying by Microwave Radiation
(Dnipro University of Technology, 2021) Solonenko, L. I.; Repiakh, Serhii I.; Uzlov, Kostiantyn; Mamuzich, I.; Kimstach, Tetiana; Bilyi, Oleksandr
ENG: Purpose. Kinetics research and description of drying by microwave radiation mechanism development of quartz sand and its mixes with sodium silicate in limited quantity of water steam medium. Methodology. Distilled water, sodium silicate solute and quartz sand have been used in this research. Study has been performed on sand samples weighing 200 g. Mixtures drying and structuring have been performed by microwave radiation with power of 700W with frequency of 2.45 GHz in air and in saturated water weighing 1 g steam medium. Accuracy of temperature measurement is 1, mass is 0.02 g. Realized in this investigation drying kinetics has been specified as specimen weight change dependence and moisture evaporation from this mixture rate vs. drying duration. Dependencies have been built on the results of video recording and corresponding chrono-gravimetric measurements data digitalization. Mixtures during heating by microwave radiation temperature changes registration has been performed with an interval of 1560 s. Samples average heating rate has been estimated by calculation based on results in their temperature change determination during first 2 minutes of heating with microwave radiation. Findings. For the first time, microwave drying kinetics of quartz sand and its mixtures with sodium silicate in limited water medium (structured by SMS-process) has been studied. For the first time, based on SMS-process material balance, analytical dependence has been developed. This dependence application allows sand-sodium-silicate mixture structured by SMS-process maximum mass to calculate when using sodium silicate solute (silicate module 2.83.0) for quartz sand cladding and 1 g of saturated water steam for mixture structuring. It has been established that when mixtures structuring according to SMS-process water extraction from them takes place in three stages at ~100, 100108 and at 125138. Maximum appropriate heating temperature of sand-sodium-silicate mixture during structuring by SMS-process has been recommended as ~125. Exceeding of specified temperature leads to hydrated water from mixture releasing in steam form and its condensation on colder working surface of model-rod rigging. Resulting condensate leads to mixture restructuring in contact with equipment places and, accordingly, sharp quality deterioration in prepared molds and rods. For manufactured molds and rods quality stabilization, it has been recommended to pre-dry the quartz sand cladded with sodium silicate solute in microwave field for at least 3 minutes before structuring according to SMS-process. Originality. For the first time, data on drying kinetics has been obtained and quartz sand and its mixtures with sodium silicate in limited water steam medium microwave drying mechanism description has been developed. Influence of number of SMS-process basic parameters on structured quartz sand weight regularities has been established. Practical value. Research results will be useful in terms of ideas expanding about the processes that accompany granular materials drying, as well as in technologies and equipment for drying and structuring fine-grained dielectric materials and their mixtures development, creating new capillary-porous media, etc. under microwave radiation influence.
Method of Lines in Distributed Problems of Experimental Data Processing
(RS Global Sp. z O.O., Poland, 2021) Shvachych, Gennady Grygorovych; Vozna, Nataliіa; Ivashchenko, Olena Valerievna; Bilyi, Oleksandr; Moroz, Dmytro
ENG: In many cases, the mathematical support of non-stationary thermal experiments is based on methods for solving the inverse heat conduction problem (IHCP), which include boundary thermal conditions determination, identification of heat and mass transfer processes, restoration of external and internal temperature fields, etc. However, at present, the main field of the IHCP application remains the processing and interpretation of the results of the thermal experiments. It was here where the most considerable theoretical and applied successes were achieved in methods' effectiveness and the breadth of their practical use. This paper highlights the issues of mathematical modeling of multidimensional non-stationary problems of metallurgical thermophysics. The primary research purpose aims at solving problems associated with identifying parallel structures of algorithms and programs and their reflection in the computers’ architecture in solving a wide range of applied problems. Supercomputers are currently inaccessible due to the enormous cost and service price. In this regard, a real alternative is cluster-type computing systems by which the simulation results are covered in this paper. Being a relatively new technology, cluster-type parallel computing systems are useful in solving a large class of non-stationary multidimensional problems, while allowing to increase the productivity and quality of computations. The software developed in this paper can be used to plan and process the results of a thermophysical experiment. The algorithms developed in the application program package are simply reconstructed to solve other coefficient and boundary problems of thermal conductivity. The developed algorithms for solving thermophysical problems are highly accurate and efficient: the test solution for IHCP with accurate input data coincides with the thermophysical features of the sample material. The developed software for processing the results of a thermophysical experiment is self-regulating. Moreover, it is quite merely tuned to the solution of others and, in particular, of boundary IHCP.
Optimization of Production Process of Structural Steel Modified with Nitrogen and Vanadium
(Latvia University of Life Sciences and Technologies, Jelgava, 2022) Aftandiliants, Yevhenii; Gnyloskurenko, Svyatoslav; Meniailo, Helena V.; Khrychikov, Valerii Ye.
ENG: Structural steels are the most promising material, particularly in machine design. An important issue is to match their properties with the exploitation demands. It can be achieved by the optimization of the steel production process, i.e. formation of the primary and secondary structure under modification with nitrogen and vanadium, proposed in this research. At the experiments the structural steels were melted, modified with nitrogen and vanadium, subsequently deoxidized with aluminium, cerium and lanthanum. The steel samples were tested to reveal the mechanical properties and study the effect of modifying processing. The results have shown that some decrease in plastic properties, the impact strength and an increase in the critical temperature of brittleness is not due to vanadium nitride hardening of steel, but could be associated with imperfect technology. The final deoxidation of steel is often performed with aluminum of at least 0.05% in order to stabilize the grain of the structure during austenitizing heating. It was established that the necessary condition for the effective influence of nitrogen and vanadium should be a higher formation temperature of vanadium nitrides than aluminum nitrides in steels. Calculations showed that this condition is realized when the content of aluminum in steel is less than 0.03% and vanadium - 0.10%. The results of the performed experiments have shown that in this case there is a simultaneous increase in the strength properties and impact toughness of steel. Based on the obtained results the recommendations for the industrial process of steel making was formulated as below. In foundry shops with inductional melting furnaces it is necessary to additionally deoxidize steel with cerium and lanthanum. So, comprehensive optimization of the content of nitrogen, vanadium and deoxidizers in steel, as well as the temperature of austenitizing heating ensure increase in mechanical properties without reduction in plasticity and toughness.
Physicochemical Structure Features of Refractory Compositions with Inorganic Binders
(Vasyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine, 2022) Liutyi, R. V.; Solonenko, L. I.; Osipenko, I. O.; Fedorov, M. M.; Moroz, B. I.
ENG: The article presents the study results of new inorganic binders and the physicochemical processes of their formation. The main purpose of the created materials is to make molds and cores for foundry production. Creating environmentally-friendly binders with a set of functional properties for foundry production is relevant worldwide. Therefore, scientists from different countries are paying special attention to the study of silicate and phosphate binders. The study analyzes the kinetics of the orthophosphoric acid interaction with several inorganic materials – pulverent pyrophyllite, disthene-sillimanite, a by-product of electrocorundum production, and sodium chloride. The phase and chemical composition of all formed binders have been established. In aluminum-containing compositions, those are represented by aluminum orthophosphates in crystalline and amorphous forms. Sodium metaphosphate is formed in the composition with sodium chloride. Peculiarities of the structuring compositions physical process with liquid glass and granular quartz filler due to steam-microwave treatment are determined. It is shown that structuring occurs due to dehydration, which is completed within 4…12 min, which allows reducing the liquid glass content in the composition to 1.5% while ensuring a high level of strength. The properties of structured compositions with the developed binding components are researched, and it is shown that all of them are competitive. Recommendations for their possible application were created.
The Process of Vacuum Formation in the Shrinkage Cavity at Castings Crystallization
(The Katowice Branch of the Polish Academy of Sciences, Poland, 2022) Khrychikov, Valerii Ye.; Semenov, Oleksandr D.; Meniailo, Helena V.; Aftandiliants, Y.; Gnyloskurenko, S.
ENG: The formation process of one of the most common casting defects, a shrinkage depression concerned to shrinkage cavity, was studied. The methodology, device and the experimental set up were developed to study the shrinkage cavity growth. The kinetics of vacuum formation in the cavity of the spherical casting of Al-Si-Mg alloy at its solidification in the sand-and-clay form was investigated. The data were analysed taking in mind the temperature variation in the centre of crystallizing casting. The causes of the shrinkage depression in castings were clarified. It was determined that atmospheric pressure leads to the retraction and curvature of metal layer on the surface of the casting with lower strength below which the shrinkage cavity is formed. To avoid such defects it was recommended to use the external or internal chills, feeders and other known technological methods. Deep shrinkage cavities inside the castings could be removed with an air flow through a thin tubular needle of austenitic steels for medical injections.
Regularities of Crystallization Heat Release During Solidification of Alloyed Cast Irons
(The Katowice Branch of the Polish Academy of Sciences, Poland, 2023) Aftandiliants, Y.; Gnyloskurenko, S.; Meniailo, Helena V.; Khrychikov, Valerii Ye.; Lomakin, V.
ENG: The chemical composition of alloys plays an important role at their crystallization and influences the solid phase formation, and thus, microstructure and properties. The present paper studies the release of the heat of crystallization of alloyed wear-resistant cast irons in order to determine the quantitative patterns of the chemical composition influence to the kinetics of crystallization. The differential thermal analysis was applied to get the data of heat release, its rate at cast iron temperature decrease. The normalized dependence of the amount of crystallization heat over time was obtained. The main temperature parameters were analyzed and four stages at irons crystallization were established and characterized with their duration and released heat. The multiple correlation analysis allowed considering a numerous physical and chemical factors and distinguishing their role at crystallization of irons. As a result, the quantitative regularities are determined of influencing the content of alloying elements, impurities and carbides on a heat and time of crystallization at the different stages of solidification, which are of great importance in developing alloyed irons with required quality and properties.
Structural Formation Regularity of Cu-Sn-Si System Low-Tin «Singing» Bronze
(Baltija Publishing, 2022) Uzlov, Kostiantyn Ivanovych; Mazorchuk, Volodymyr Fedorovych; Dziubina, Alina Valentynivna
ENG: Based on the task of acoustic bronzes containing about 20%Sn cost reducing, the aim of economically alloyed bronze composition with expensive tin replacement by silicon developing has been formulated in the present work. Three-component system Cu-Sn-Si bronzes structure formation has been studied and conodes triangle copper corner alloys phase transformations regularities were determined. It was established that in Cu-Sn-Si system alloys with Si content more than 4wt.%, original β-phase is stabilized by silicon and in solid state does not undergo low-temperature eutectoid transformations with small (up to 4wt.%) tin amount in bronze. It is shown that this «singing» bronze structural state is the basis for two systems of structural stresses in castings body existence, which act as acoustic resonators in products material. These systems are: α-Cu solid solution liquated areas of different genesis and interphase boundary α-Cu↔β-Cu5Sn, which causes occurrence of II type internal structural stresses between α-Cu and chemical compound Cu5Sn, which are fundamentally dissimilar in nature. For the first time, with comprehensive using of scanning electron microscopic, X-ray spectral, energy dispersive, X-ray structural phase and metallographic studies of Cu-Sn-Si alloys with optimized composition (silicon 4.5...5.5% by mass and tin 2...5% by mass at mass ratio Si/Sn≥1), tin-silicon bronzes with main components optimal ratio structural formation regularities are established. New bronze for bells and percussion musical instruments in terms of strength and impact toughness exceeds «classical» bell bronze indicators by~1.5...2.5 times with comparable relative elongation values. This evidences that, compared to «classic» bell bronze, elaborated cast bronze products with developed optimal chemical composition are characterized by greater reliability and durability during operation within its application specified area. Present work innovative solutions on methods of making musical bronze, obtaining bronze castings and making bells and percussion musical instruments acoustic elements are covered by intellectual property protection documents.
Synthesis of Phosphosulphate Substance and Properties of Its Structured Mixture with Quartz Sand
(Dnipro University of Technology, Ukraine, 2022) Liutyi, R. V.; Tyshkovets, M. V.; Yamshinskij, M. M.; Selivorstov, Vadim Yu.; Ivanov, V. G.
ENG: Purpose. Creation of binder based on orthophosphoric acid and aluminum sulfate, study on its structure and physicochemical patterns of formation, determination of the properties of structured mixtures for the needs of foundry. Methodology. In the work, X-ray qualitative and quantitative analysis was performed on the Rigaku Ultima IV unit, and differential thermal analysis was performed on the STA 449 C Jupiter synchronous thermal analyzer. Orthophosphoric acid, technical thermal, of 85% concentration, 18-hydrous sulfate of aluminum Al2(SO4)3 18H2O and quartz sand of brand 3K5O3025 were used. The strength of core mixtures was determined on the US-700 unit on standard cylindrical samples with a diameter and height of 50mm. The roughness of the cast surfaces was determined on a profilometer model 107622 with computer processing of the obtained data and construction of profilograms. To determine the propensity of the core mixtures to form caking, a hexagon sample was used according to the method by M. Fedorov. Breakability was determined on standard cylindrical samples with a diameter and height of 50 mm according to the original method described in the text of the article. Findings. For the first time, the mechanism of formation of aluminum phosphates with binding properties during the interaction of aluminum hydrate crystal sulfate Al2(SO4)3 18H2O with orthophosphoric acid in the temperature range of 100200 has been investigated. The formation is proved of an intermediate phase during heating aluminum hydroxide Al(OH)3, which, in contrast to its sulfate, according to the results of thermodynamic analysis is able to interact with acid. Formation of aluminum in the system of ortho- and metaphosphates, which features binding properties and ensures high strength of samples based on quartz filler, has been established. The thermal transformations of the obtained binder, which consists of a combination of aluminum phosphates with its residual sulfate, are studied. Stages of gradual disintegration of crystal hydrates, formation of new aluminum phosphates and thermal decomposition of residual sulfate are recorded. The tendency to burn and knockout of the developed core mixtures was determined. Originality. For the first time, a description has been developed of the mechanism of formation of aluminum phosphates with binding properties during the interaction of its sulfate crystal hydrate Al2(SO4)3 18H2O with orthophosphoric acid in the temperature range of 100200. Practical value. A new inorganic binder from orthophosphoric acid and 18-aqueous aluminum sulfate has been obtained for foundry production. The scheme of its preparation involves preliminary mixing and heating of the specified reagents with the resulting formation of a dry powder material which consists of phosphates and residual aluminum sulfate, and therefore it is called phosphosulfate. The binding has a long shelf life and is introduced into the mixture in a ready-made form while the technology of its production is less energy-intensive and long-lasting compared to the preparation of traditional metal phosphate binding.
Synthesis of Phosphosulphate Substance and Properties of Its Structured Mixture with Quartz Sand
(Dnipro University of Technology, Dnipro, Ukraine, 2022) Liutyi, R. V.; Tyshkovets, M. V.; Yamshinskij, M. M.; Selivorstov, Vadim Yu.; Ivanov, V. G.
ENG: Purpose. Creation of binder based on orthophosphoric acid and aluminum sulfate, study on its structure and physicochemical patterns of formation, determination of the properties of structured mixtures for the needs of foundry. Methodology. In the work, X-ray qualitative and quantitative analysis was performed on the Rigaku Ultima IV unit, and differential thermal analysis was performed on the STA 449 C Jupiter synchronous thermal analyzer. Orthophosphoric acid, technical thermal, of 85 % concentration, 18-hydrous sulfate of aluminum Al2(SO4)3  18H 2O and quartz sand of brand 3K5O3025 were used. The strength of core mixtures was determined on the US-700 unit on standard cylindrical samples with a diameter and height of 50 mm. The roughness of the cast surfaces was determined on a profilometer model 107622 with computer processing of the obtained data and construction of profilograms. To determine the propensity of the core mixtures to form caking, a hexagon sample was used according to the method by M. Fedorov. Breakability was determined on standard cylindrical samples with a diameter and height of 50 mm according to the original method described in the text of the article. Findings. For the first time, the mechanism of formation of aluminum phosphates with binding properties during the interaction of aluminum hydrate crystal sulfate Al2(SO4)3  18H2O with orthophosphoric acid in the temperature range of 100–200 °С has been investigated. The formation is proved of an intermediate phase during heating – aluminum hydroxide Al(OH) 3, which, in contrast to its sulfate, according to the results of thermodynamic analysis is able to interact with acid. Formation of aluminum in the system of ortho- and metaphosphates, which features binding properties and ensures high strength of samples based on quartz filler, has been established. The thermal transformations of the obtained binder, which consists of a combination of aluminum phosphates with its residual sulfate, are studied. Stages of gradual disintegration of crystal hydrates, formation of new aluminum phosphates and thermal decomposition of residual sulfate are recorded. The tendency to burn and knockout of the developed core mixtures was determined. Originality. For the first time, a description has been developed of the mechanism of formation of aluminum phosphates with binding properties during the interaction of its sulfate crystal hydrate Al2(SO4)3  18H2O with orthophosphoric acid in the temperature range of 100–200 °С. Practical value. A new inorganic binder from orthophosphoric acid and 18-aqueous aluminum sulfate has been obtained for foundry production. The scheme of its preparation involves preliminary mixing and heating of the specified reagents with the resulting formation of a dry powder material which consists of phosphates and residual aluminum sulfate, and therefore it is called phosphosulfate. The binding has a long shelf life and is introduced into the mixture in a ready-made form while the technology of its production is less energy-intensive and long-lasting compared to the preparation of traditional metal phosphate binding.
Water Resistance of Structured Sand-Sodium-Silicate Mixtures
(Dnipro University of Technology, 2021) Solonenko, L. I.; Repiakh, Serhii I.; Uzlov, Kostiantyn I.; Mamuzich, I.; Bilyi, Oleksandr P.; Kimstach, Tetiana V.
ENG: Purpose. To establish regularities of changes in sand-sodium-silicate mixtures (SSSM) relative water resistance, structured by steam-microwave solidification method (SMS), on their structuring parameters and sodium silicate solute (SSS) dissolution conditions. Methodology. Technical purity water, SSS with 2.8–3.0 silicate modulus, quartz sand with 0.23 mm average particle size were used in this work. Studies were carried out on quartz sand samples, which were preliminarily cladded with 0.5–2.5 % (by weight) SSS and structured by SMS method. The fracture time of structured mixtures was evaluated on cubic specimens with 20 mm rib length, which were immersed in water at different temperatures. Findings. Changes in SSSM water resistance in water regularities depending on their manufacturing, use and storage conditions were established. Recommendations for SSSM rods removal from castings in water were developed. Originality. For the first time, it has been established that relative water resistance of the SSSM structured by SMS method decreases along with increase in water temperature in which it is destroyed. Depending on SSS mass used for quartz sand cladding in range 0.5–2.5 %, water resistance dependence on treatment in steam-microwave environment with 2–7 minutes’ running time acquires an inversion character with inversion point ∼3.1 minutes into the processing. For the first time, it has been discovered that in boiling water the relative water resistance of SSSM, structured by SMS-process and having preheating, monotonically increases with preheating temperature rising from 100 to 600 °С, sharply increases when heated to 600–700 °С and practically becomes absolute after preliminarily preheating to higher temperatures. Practical value. Research results will be useful in concepts of processes accompanying destruction of structured sands with water-soluble binders expanding, as well as in technologies and equipment development designed for SSS rods and mold rests removing from castings.
Аналіз ефективності перемішування компонентів залізофосфатної суміші у сухому стані
(НМетАУ, Дніпро, 2021) Селівьорстов, Вадим Юрійович; Доценко, Юрій Валерійович
UKR: Представлені результати досліджень впливу часу перемішування вихідних компонентів у сухому стані на ступінь засвоєння залізовмісної складової формувальних та стрижневих залізофосфатних холоднотвердіючих сумішей. Експериментально визначений відсоток засвоєння дисперсної залізовмісної складової через кожну хвилину перемішування в лабораторних бігунах при загальному часі перемішування протягом 15 хвилин. Використовуючи оригінальну методику відокремлювання часток, під мікроскопом відділяли частинки окалини, що не засвоїлися (не розподілилися на поверхні піщинок), і зважували їх. Отримані залежності ступеня засвоєння металевої складової залізофосфатної суміші від часу перемішування при різному її початковому вмісті. Показано, що найбільший ступінь засвоєння залізовмісної складової залізофосфатних сумішей досягається в результаті перемішування складових суміші протягом перших чотирьох – п’яти хвилин. Потім цей показник починає знижуватися, оскільки починають руйнуватися піщинки під дією навантаження валків бігунів, а також знижуються сили електростатичної взаємодії між поверхнями піщинок і дисперсійним середовищем в порівнянні з силами взаємного тяжіння між дисперсними частинками залізовмісного компоненту суміші. Опираючись на приведений аналіз теоретичних положень та отриманих результатів експериментальних досліджень, висловлене припущення про можливість регулювання умов і параметрів твердіння фосфатних пов’язувальних систем, зокрема використанням залізовмісного наповнювача певної дисперсності та перемішуванням компонентів суміші в сухому стані протягом певного часу. Відомо, що для перемішування компонентів і засвоєння необхідної частини залізовмісної складової суміші використовується значна кількість енергії (в залежності від типу використовуваного агрегату). Для зниження енергоємності цього процесу актуальною задачею є визначення ступеня засвоєння залізовмісної складової фосфатних холоднотвердіючих сумішей при їх виготовленні за допомогою перемішування складових саме в сухому стані.
Аналіз поведінки водню при кристалізації вторинних алюмінієвих сплавів
(НМетАУ, Дніпро, 2021) Трегубенко, Ганна Василівна; Меняйло, Олена Валеріївна
UKR: Мета. Дослідити поведінку водню при кристалізації вторинних алюмінієвих сплавів. Методика. Виконано моделювання процесу поведінки водню при кристалізації вторинних алюмінієвих сплавів. Результати. Виконано аналіз поведінки водню при затвердінні відливок із вторинних алюмінієвих сплавів. Отримані вирази для розрахунку поточних значень у процесі кристалізації вторинних алюмінієвих сплавів концентрацій водню в примежовому дифузному шарі, на фронті кристалізації, в об’ємі розплаву, який залишився і ефективного коефіцієнту розподілення водню. Наукова новизна. Уперше отримана математична модель для прогнозування поведінки водню в процесі затвердіння вторинних алюмінієвих сплавів. Практична значущість. Результати роботи можна застосовувати на практиці з метою оптимізації технологічного процесу і більш ефективного використання дорогоцінного обладнання для отримання якісних відливок із вторинних алюмінієвих сплавів.

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