Статті КЛВ (ДМетІ)

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Adaptation of a Predicate Model in Control Problems of Nonstationary Static Objects
(Український державний університет науки і технологій, ННІ ≪Дніпровський металургійний інститут≫, ІВК ≪Системні технології≫, Дніпро, 2025) Tryputen, Mykola; Kuznetsov, Vitalii V.; Yvanova Lyudmyla Kh.
ENG: When controlling static objects at the optimization level, pattern recognition methods are used that allow partitioning the factor space into elementary subdomains in the form of n-dimensional hyperparallelepipeds. One of the main elements of the control structure for this approach to control is the adaptation algorithm, that makes it possible to refine the description of a static object under nonstationarity conditions. Repeated use of the adaptation algorithm to refine the model leads to an unjustified complication of its logical structure and the accumulation of information that has lost its relevance. The paper proposes a method for minimizing the description of images of technological situations, that makes it possible to overcome the indicated disadvantages. The method is based on the property of invariance of the number of parameters defining the hyperparallelepiped to the size of the described area in the factor space. This made it possible to identify significant boundary sub-areas in the description of the image of technological situations and, by their subsequent combination in the direction of the feature axes, to select a description with a minimum number of sub-areas. When performing these operations, “outdated” information is removed and the logical structure of a static control object is simplified as much as possible. The paper shows the possibility of implementing an algorithm for minimizing the description of images on the basis of α-algebra, that makes it possible to integrate its control structures using relational data models. The effectiveness of the proposed algorithm is confirmed by computational experiments in the control of the process of lump crushing for the conditions of a mining and processing plant.
Advanced Space Vector Modulation with “Fractional” Power Cells
(Elsevier B.V., 2025) Busher, Victor; Shestaka, Anatoliy; Melnikova, Lubov; Kuznetsov, Vitaliy V.; Mykhailenko, Oleksii; Kovalenko, Viktor; Kutyk, Viktor; Osadchyi, Dmytro; Osypenko, Iryna O.; Abdel Gawad, Samer
ENG: The paper develops a model and studies various operating modes of a 5-phase multi-level cascade inverter as part of high-voltage powerful variable-frequency drives (VFD) with the most typical fan load for this type of electric drives. The aim of the work is to test the efficiency of the balanced spatial-vector pulse-width modulation method in a multi-phase high-voltage multi-level inverter in emergency modes by simulating the electric drive in the MATLAB/SIMULINK/Simscape Electrical environment. The paper studies the features of using the balanced spatial-vector pulse-width modulation method in a five-phase frequency converter in normal and emergency modes and, especially, the differences from a three-phase inverter with a similar control principle. The model with a 5-phase synchronous motor from the MATLAB ac8_example.slx database is taken as a basis, which allows us to consider the simulation results reliable. The rules for calculating phase voltages in normal and emergency modes are formulated and the corresponding blocks of the inverter control system model are prepared - a block for calculating basic vectors and a block of spatial vector pulse-width modulation (PWM). The output signals of this block are used for further processing in the modules for controlling power cells with 2- or 3-level PWM. Such a model for a 5-phase electric drive has been built for the first time, which is a scientific novelty of the work. Calculations of transient processes showed the absence of any oscillations, shocks when the system switches from normal to emergency mode and vice versa. That is, the proposed method of balanced spatial vector modulation preserves the symmetry of electromagnetic fields in the engine when individual H-bridges are damaged. It is shown that in normal mode, a 5-phase inverter using the spatial vector modulation method allows increasing the utilization factor of voltage sources by 23.1%. When individual power cells in phases fail, the utilization factor may decrease, but in any case it remains greater than 1. The method ensures compensation for emergency damage even in the event of a short circuit of one or two inverter phases. This significantly increases the service life of the electric drive, which is especially important in critical mechanisms and technological processes, where such complex inverters are actually used. The study found that when using the proposed method in a 5-phase VFD, unlike a 3-phase one, the current balance in the load is disrupted, which leads to increased heating of individual phases of both the motor and the power section of the inverter. The second point of scientific novelty of the work is that in order to reduce this negative effect, it is proposed to improve the algorithm for calculating the output coordinates of the regulator by using the so-called “fractional” power cells with a voltage that is not a multiple of their rated voltage. This leads to a smooth change in phase shifts and asymmetry when individual H-bridges and even one or two phases are damaged. This, in turn, reduces the current imbalance and the corresponding overheating from 2...3 to 12...15%, which gives confidence in the efficiency of using this improvement. It is also important to note that such a change in the control algorithm does not require any changes in the circuit and does not increase the requirements for the computing power of the processors used.
Alumophosphate Binders: Synthesis, Phase composition, Thermal Stability and Application in Foundry Production
(Elsevier B.V., Netherlands, 2025) Petryk, Ivan; Liutyi, Rostyslav V.; Osypenko, Irina O.; Myslyvchenko, Olexander; Byba, Ievgen; Lukianenko, Ivan
ENG: Organic binders currently used in the foundry industry are highly toxic. During the pouring of casting molds, many volatile organic compounds are released, the vast majority of which are environmentally harmful. The development of alumophosphate binders will have a positive impact on the environment. The article gives the results of the study of aluminum phosphate binders, which are the result of the chemical reaction of orthophosphoric acid with powdered aluminosilicates. The subjects of the research are the phase and chemical composition, the dynamics of thermal transformations of the binders, as well as the properties of core mixtures for the production of foundry cores. It was found experimentally that as a result of the chemical reaction of powdered pyrophyllite Al2(OH)2[Si4O10] and disten-sillimanite Al2O[SiO4] with orthophosphoric acid after heating to 300 оС, strong and thermally stable binders are formed, which are crystalline and amorphous aluminum orthophosphates. These phases ensure binding of the quartz refractory filler and therefore high strength. Synthesized binders can be used in refractories or core mixtures for foundry production. X-ray phase and differential thermogravimetric analyzes were used to determine the structure and properties of binders. The compositional planning of the experiment with appropriate data processing was applied to determine the working composition of the mixture for foundry cores. The structure of aluminum phosphate binders, which were obtained using refractory fillers common in foundry production, was investigated for the first time. The circumstances for the formation of crystalline phases were analyzed for the first time. It was established that as a result of the reaction of orthophosphoric acid and disten-sillimanite, the larger specific amount of aluminum orthophosphate and the smaller amount of residual quartz is formed, compared to the reaction of acid with pyrophyllite. This ensures the higher strength of the core mixture, which is formed from the binders in which orthophosphoric acid and disten-sillimanite are used. Taking into account the mass ratios for the whole realization of the chemical reaction of the formation of the aluminum phosphate binders, the core mixture on the basis of quartz sand, orthophosphoric acid and disten-sillimanite was developed, which hardens after heating to 300 оС and has a compressive strength of at least 2.0 MPa.
Assessing Criteria for Casting and Deformation Suitability of Metals and Alloys
(Dnipro University of Technology, Dnipro, 2025) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Mazorchuk, Volodymyr F.; Repyakh, Serhii I.
ENG: Purpose. Based on existing criteria for predicting the suitability of metals and their alloys for manufacturing products from them by deformation or casting analysis develop a set of dimensionless parametric criteria and their quantitative scales. Their using will allow increasing the predicting accuracy of metals and alloys for their processing by pressure or casting suitability and feasibility. Methodology. The work uses phenomenological approach to systematic analysis results of metals and alloys mechanical and individual casting properties interpreting under uncertainty conditions, drawing on literature reference data, expert evaluation data and the authors’ own research results. The authors’ own data have been obtained experimentally using standard methods for mechanical properties determining and due to original authors’ method for technical purity metals and alloys based on them cast samples values of their absolutely hindered linear shrinkage determination during casting. Findings. The authors first proposed parametric dimensionless criteria and scales to them (criteria groups). Their application allows one, through such groups combinations, to assess suitability of any alloy or metal for its use possibility for products manufacturing by casting and/or pressure processing. Originality. For the first time dimensionless parametric criteria have been developed and proposed for use at initial stages of new alloys or technologies elaboration for products from them manufacturing as well as their quantitative scales for preliminary assessment (prognosis) of alloys processing feasibility by pressure or casting, regardless of their type and method. Practical value. Developed criteria and their quantitative scales using will allow alloys developers and specialized enterprises employees to save time and expenses both for alloy elaboration and for its implementation into production.
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.
Complex Solid-Phase Reduction in a Blast Furnace of Self-Healing Pellets of Cold Agglomeration Containing By-Product Carbon Materials of Metallurgical Production
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Vaniukov, Anton A.; Ivashchenko, Valerii P.; Ivanova, Liudmyla Kh.; Kovalov, M.; Tsybulia, Ye.
ENG: The reactions of direct and indirect reduction occurring during the heat treatment of self reducing pellets (SRP) have been studied. In this investigation Blast furnace (BF) sludge which contains particles of coke, has been included in the SRP blend as a source of solid reductant. In the SRP as a part ot the blast furnace burden occur the reactions simultaneously: inside of SRP-direct reduction by Csolid; gasification of carbon and indirect reduction by CO; and outside of SRP-indirect reduction of iron bearing oxides by reducing gas coming from the hearth of blast furnace through the column of charged materials. The experiments was performed continuously from the start temperature (~200 ˚C) to the experimental temperature (500 ˚C; 700 ˚C; 900 ˚C; 1100 ˚C) in argon free environment. Upon reaching the desired temperature argon was replaced by hydrogen during 30 minutes. After that the reduced probe of SRP was cooled in argon. The objective of the present work is to research a quantitate ratio of degree direct reduction inside of SRP and degree of indirect reduction outside of SRP on the top of the blast furnace.
Construction of a Kinetic Equation of Carbon Removal for Controlling Steel Melting in the Metallurgical System "Cupola Furnace – Small Converter"
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Makarenko, Dmytro M.; Selivorstova, Tetiana V.; Dotsenko, Yuriy V.; Osypenko, Iryna O.; Dzevochko, Oleksandr M.; Pereverzieva, Alevtyna M.; Dzevochko, Alona I.
ENG: The object of research in the paper is the process of steelmaking in a small converter, which works in tandem with a cupola furnace. The existing problem is that the control of the process of obtaining steel in an oxygen converter is complicated by the need to determine in real time the current chemical composition of the melt, in particular carbon. This is due to the fact that the rate of carbon removal is too high, as a result of which the process of carbon removal is transient. Therefore, it is too difficult to implement regulation based on feedback on continuous measurement. The presence of the specified problem requires solutions related to the possibilities of developing or improving software control of the process. It is shown that in certain sections of the process within each time section of oxygen purging of the melt in the converter, the kinetic curve has a linear form with a constant coefficient value in front of the inlet mine. But the value of the initial coefficient for each equation that describes the process within its limits changes. This allows to state that in case of a change in the initial condition, the kinetic curves shift relative to each other in parallel. On this basis, a system of equations has been constructed that describes the process of carbon removal in a small oxygen converter that receives liquid iron from a cupola furnace. It has been shown that to use the obtained system of equations, it is necessary to know the initial carbon content in the melt discharged from the cupola furnace, and it depends on the method of oxygen supply to the cupola furnace. Based on the modeling of this process in two variants – using a “sharp blow” and supplying oxygen to the air blown into the tuyeres, a nomogram has been constructed. It allows to determine the initial carbon content for the practical use of the obtained system of equations. Using the obtained system makes it possible to determine the time after which oxygen cutoff should be made. This will allow to decide to implement software control of the melt blowing process in the converter. The presented study will be useful for machine-building enterprises that have foundry shops in their structure, where cast iron is smelted for the manufacture of castings.
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.
Determination of Bronze БрА7К2О1,5Мц0,3 Crystallization Interval Limit Values and Phase Transformations
(Dnipro University of Technology, Dnipro, 2025) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Solonenko, Lyudmila I.; Repyakh, Serhii I.
ENG: Phase transformations temperatures, crystallization intervals, etc. are any alloy’s fundamental parameters. Alloys’ casting, technological and operational properties are related to them. Nevertheless, unlike two-component bronzes, such requirements for multi-component structural, non-magnetic, corrosion-resistant bronze БрА7К2О1,5Мц0,3 are absent. Purpose. For Cu-Al-Si-Sn-Mn system bronzes, crystallization intervals quantitative values (liquidus and solidus temperatures, crystallization interval size and solid phase relative share in it) have been established. БрА7К2О1,5Мц0,3 bronze’s alloying components’ synergistic and selective influence on its crystallization interval and relative fluidity indicators changing has been determined. Methodology. Well-known methods and research techniques, including thermography, differential thermal analysis, spectral chemical analysis, images analysis digital method have been used in this work. Bronzes fluidity has been assessed using spiral test. Bronze’s alloying elements’ synergistic and selective influences on its characteristics have been determined using chemical elements ratio in it (KR criterion) and experimental data results processing by Excel computer program. Findings. In bronze БрА7К2О1,5Мц0,3 with KR criterion value rising from 0.35 to 0.84, there increase liquidus, solidus temperatures and crystallization interval from 32 to 49 °C. Bronze’s alloying elements’ (Al, Si, Sn, Mn) synergistic and selective influences on its crystallization interval limit values have been determined. It has been established that conditionally-veritable fluidities of БрА7К3О1,5Мц0,3 and БрА9Ж3Л bronzes are practically the same. For Cu-Al-Si-Sn-Mn system bronzes with KR = 0.35‒2.07, solid phase relative volume fraction (φSP) in crystallization temperature range is 60‒63 %. Originality. For the first time, limiting values and phase transformations for БрА7К2О1,5Мц0,3 bronze’s crystallization interval and alloying elements synergistic and selective influence on these indicators have been determined. Practical value. Based on БрА7К2О1,5Мц0,3 bronze’s chemical composition selected, mathematical models have been proposed for its liquidus and solidus temperatures calculating and for transition from dependences of solid phase t(φSP) volume fraction in crystallization temperature range to temperatures’ absolute values t(φSP). Their use will allow increasing the indicators of foundry and technological parameters accuracy forecasting.
Determination of Conditions for Preventing Chemical Wear of Induction Furnace Lining in the "Cupola Furnace – Induction Furnace" Duplex Process
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Nikolaev, Denis A.; Selivorstov, Vadim Yu.; Dotsenko, Yuriy V.; Osypenko, Iryna O.; Kuznetsow, Eugene V.
ENG: The object of research is the melting of cast iron in the “cupola furnace – induction furnace” duplex process. The need to study such a duplex process is dictated by the condition of ensuring the required quality of cast iron in the event that a low-quality or uncontrolled charge is used. This condition cannot be met if the induction furnace is used as the only melting unit. But the problem is that in the process of induction melting of cast iron, in particular at the stage of overheating and holding the melt, a crucible reaction may begin, which leads to chemical wear of the lining. The need to reduce the carbon content in the melt discharged from the cupola furnace requires an increase in temperatures, which creates risks for the onset of a crucible reaction. Based on statistical calculations of cupola melting parameters, it was found that in the melt discharged from the cupola furnace into the induction furnace, the average carbon content is C = 3.47% with a standard deviation SC = 0.14%, and the average silicon content is Si = 2.05% with a standard deviation SSi = 0.21%. At the same time, with a probability of 96%, the carbon content is C = (3.33–3.75)%, and the silicon content corresponds to the range Si = (1.84–2.46)% with a probability of 98%. It was found that the equilibrium constant is in the range (0.15–0.21) with a probability of 97.8% at an average temperature T = 1355°C with a standard deviation of temperature ST = 6°C. With such melt parameters, which are supplied to the induction furnace, the risks of the onset of a crucible reaction do not arise. It was determined that even at temperature regimes sufficient to remove FeO, the risk of the onset of a crucible reaction is minimal. In order to ensure conditions that prevent the onset of a crucible reaction, the following recommendations should be followed for the content of carbon and silicon in high-temperature melting when the temperature is in the range T > 1480°C: C > 0.3% and Si < 0.3%. The results of the study can be used in the melting sections of foundries equipped with cupola furnaces and induction furnaces.
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.
Distribution of Chromium in Transition Layer of Bimetallic Castings
(Latvia University of Life Sciences and Technologies, Jelgava, 2025) Aftandiliants, Yevhenii; Gnyloskurenko, Svyatoslav; Meniailo, Helena V.; Khrychikov, Valerii Ye.
ENG: The constantly increasing requirements for machine components and mechanisms operating under conditions of impact and abrasive wear determine promising use of bimetallic cast parts. Their quality significantly depends on both the technological factors of manufacture and the properties of the transition layer between the base and the working layer. The aim of the work was to study the influence of the casting mass, the ratio of the mass of the steel base and the working layer of cast iron and the difference in the chromium content in the layers, the pouring temperature of steel and cast iron on the quality of the casting. Research was carried out on bimetallic castings of steel 25L – cast iron 300Kh12G5 and steel 70GL – cast iron ChKh22. The mathematical model of the influence of selected parameters on the width of the chromium transition zone from cast iron to steel and the average rate of chromium concentration change in the transition layer was developed. It was established that the most effective influence on this zone and the rate of chromium change is exerted by the mass and temperature of the steel base, the contribution of which is 67.7% and 60.2%, respectively. It was shown that the width of this zone decreases with increasing difference in the chromium content in the matrix of the working layer and the base and expands with increasing the pouring temperature and mass of steel and cast iron. It was determined that increasing the pouring temperature and the mass of the steel base and the working layer leads to a decrease and the chromium content in the matrix of the working layer and the base to an increase in the average rate of the change of the chromium concentration in the transition layer. These data are useful for optimizing the technology of obtaining high-quality bimetallic castings.
Efficient Algorithms for Parallelizing Tridiagonal Systems of Equations
(НМетАУ, Дніпро, 2021) Shvachych, Gennady Grygorovych; Vozna, Nataliіa; Ivashchenko, Olena V.; Bilyi, Oleksandr P.; 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.
Heat Balance of Billets during Hot Extrusion of Nickel Alloy Pipes
(Ukrainian State University of Science and Technologies, Dnipro, 2026) Medvedev, M. I.; Bobukh, Oleksandr S.; Kuzmina, O. M.; Krasiuk, A. D.; Ivanova, Liudmyla Kh.
ENG: Among the problems encountered in the production of nickel-based alloy pipes by hot extrusion sleeves on horizontal hydraulic presses, one of the main ones is the high level of product surface defects. To reduce rejects on this basis, it is important to understand the changes in the temperature field of the pipe billet throughout the entire technological process, since this factor is the key to the formation of surface defects in such pipes. The purpose of the work is to establish the regularities of temperature changes in nickel alloy pipe billets at the main stages of pipe production, which are made by extrusion on presses with a force of 16.0 MN and 31.5 MN with the use of glass lubricants. Methodology. The work was performed based on the results of a systematic analysis of the main technological stages of the actual process of producing hot-extruded pipes made of nickel alloy 602CA on presses with a force of 16.0 MN and 31.5 MN. The selected production stages include: transporting the billet (liner) from the induction heater to the glass-filled table, applying glass-filled material to the billet surface, transporting the billet with glass-filled material to the press, holding the billet in a container before extrusion, and extrusion in the container. The calculation of the stepwise temperature loss by the billet was performed using known and own empirical equations obtained from the results of thermography of the billets. The chemical composition of the billets was determined using an Elvax plus spectrometer. The temperature of the outer surface of the workpiece was measured using chromium-aluminium thermocouples complete with an electronic potentiometer. Results. It was found that the total change in the temperature of the sleeves during the cooling process during auxiliary operations on presses with a force of 16.0 MN and 31.5 MN at the same initial heating temperature of the workpieces is inversely proportional to their wall thickness. At the same time, this dependence is almost linear in the range of 40...120 mm wall thickness of the sleeves and 1050...1250 °C heating temperatures of the workpiece. Scientific novelty. For the first time, a methodology for calculating the temperature of the sleeves at the main stages of their preparation for the extrusion process has been developed. Practical utility. The use of the developed methodology for calculating the temperature of the liner allows for a reasonable choice of glass lubricant for the initial technological operations of extrusion on presses with a force of 16.0 MN and 31.5 MN using glass lubricant, which in turn contributes to improving the surface quality of pressed pipes, reducing the level of pipe rejects and reducing the volume of their the volume of their further mechanical processing.
Identification of Temperature in Cupola Furnace Based on the Construction of the "Slag Composition – Slag Viscosity" Model
(TECHNOLOGY CENTER PC, Kharkiv, 2025) Nikolaiev, Denys A.; Selivorstov, Vadim Yu.; Dotsenko, Yuriy V.; Dzevochko, Oleksandr M.; Pereverzieva, Alevtyna M.; Dzevochko, Alona I.
ENG: The object of the study in the work is the temperature regime of melting in a cupola. The existing problem is that due to the aggressive high-temperature environment, continuous measurement of the parameters of the internal environment in the working space of the cupola furnace is too difficult. Even with the implementation of such a possibility, errors of the first and second types may occur. This necessitates indirect control of the temperature regime, which could provide a solution to the identification problem – whether the control system is really operating in normal mode and meets the accuracy requirements, or whether there is a parametric failure along the corresponding control circuit. The existence of the specified problem requires solutions related to the definition of criteria for evaluating the temperature regime, by which it would be possible to verify the reliable functioning of the melting control system. A criterion for evaluating the temperature regime of melting by the viscosity of the slag as a function of its composition is proposed, which allows identifying the temperature regime of melting with an accuracy of 96 %. This result is due to the proposed two-stage procedure, in which the first stage is the construction of mathematical models that describe the influence of the slag composition on the viscosity, and the second is the construction of a criterion based on the density distribution of the discriminant function for both temperature regimes. Using the obtained criterion also makes it possible to determine the areas of chemical compositions, by which the temperature regime can also be identified. The relationships between the variables for the identification procedure are presented in the form of a structural diagram. The proposed solutions will allow determining the quality of the functioning of the temperature control loop in the melting control system based on periodic control. The presented study will be useful for machine-building enterprises that have foundries in their structure, where cast iron is smelted for the manufacture of castings.
Improvement of Energy Efficiency and Environmental Safety of Internal Combustion Engines by Using Binary Fuel Mixtures with Hydrogen
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Bartashevskyi, Stanislav; Koveria, Andrii; Ovcharenko, Alina; Mazorchuk, Volodymyr F.
ENG: This paper addresses current issues related to improving the efficiency of fuel use in internal combustion engines and reducing the environmental impact of fuel combustion. It is demonstrated that incorporating hydrogen into mixtures with liquid fuels enhances the fuel’s energy potential and combustion completeness. This approach aligns with the goals of sustainable development by reducing reliance on liquid hydrocarbon fuels and mitigating the harmful effects of pollutant emissions. The study proposes producing hydrogen via chemical reactions directly at the point of use, in quantities required for operation. These reactions enable the use of readily available, non-toxic materials for the targeted generation of hydrogen and its incorporation into fuel mixtures. Calculations show that the energy consumption for decomposing 1 kg of water using diesel and AI-92 gasoline is 12.9 MJ/kg and 13.2 MJ/kg, respectively.
Improving a Technique for Producing a Polycomponent Semi-Finished Product with High Degree of Readiness for 3-D Printing of Functional Food
(РС ТЕСHNOLOGY СЕNTЕR, Kharkiv, 2024) Zahorulko, Andrii; Voronenko, Iryna; Bozhydai, Iryna; Pogarskiy, Aleksey; Ibaiev, Eldar; Ponomarenko, Nataliia; Bereza, Olena; Khytko, Oleksandr Yu.
ENG: The object of this study is the process of producing polycomponent semi-finished products of a high degree of readiness using a model structure of functional equipment, in particular, based on apple, Jerusalem artichoke, table beet, and sea buckthorn. A feature of the improved technique is the implementation of preliminary heat treatment with hot steam of raw materials: apple – 1.0...2.0 min, Jerusalem artichoke – 3...6 min, and table beet – 6...12 min, respectively. Sea buckthorn was not processed, only technological rinsing was used. Grinding of raw materials was carried out on a double grinding machine (apple, Jerusalem artichoke, and table beet – 0.2...0.5 10-3 m, and sea buckthorn – 0.5...1 mm). The combined production of polycomponent semi-finished products of a high degree of readiness (pastes/fractional powder) was implemented using a model structure of functional equipment. The boiling process in a rotary-film evaporator was carried out at a temperature of 55 °C for 65 seconds to a dry matter content of 25 %. Drying of the cooked multicomponent mass was carried out in a single-drum cylindrical IR dryer at a temperature of 50 °C to a final moisture content of 3...6 % and fractional grinding (0.3...0.6 mm). The rheological properties of the paste-like multicomponent semi-finished product were determined by the change in dynamic viscosity for composition 2, which is 485 Pa∙s, and in the control sample of applesauce, this indicator is 50 Pa∙s. When boiling in a rotary-film evaporator at a temperature of 55 °C to a content of 30 % of dry substances, there is an increase in the strength of dynamic viscosity by 3.2 times (600 Pa∙s), and in the control (apple paste) this indicator is 178 Pa∙s with a dry matter content of 25 %.
Influence of Chemical Composition on Concentration Undercooling of Structural Steels
(The Katowice Branch of the Polish Academy of Sciences, Poland, 2025) Aftandiliants, Yevhenii; Gnyloskurenko, Svyatoslav; Meniailo, Helena V.; Khrychikov, Valerii Ye.
ENG: The article studies the undercooling of steel melt around the solid particles, which is one of the main factors determining the rates of nucleation and growth of crystallization centers. Particularly, the effect of chemical composition on this factor for two grades structural cast steels 20KhGSL and 40Kh3G3S3L mainly containing Cr, Mn, Si was in the focus. The established analytical dependence allowed to determine the development of maximum concentration undercooling over the moving crystallization front depending on the liquidus temperature, the content of elements in the melt, their distribution and diffusion coefficients, the crystallization rate and the temperature gradient in the melt ahead the crystallization front. The correlation of maximum concentration undercooling and width of the columnar dendrite zone was obtained. The effect of chemical composition on steels undercooling and crystallization process was revealed. The efficiency of the elements influence changes for steels 20KhGSL and 40Kh3G3S3L from 20.1 to 25.9% for C, from 31.2 to 25.9% for Si, from 3.8 to 18.0% for Mn, from 34.0 to 10.8% for Cr, from 6.6 to 5.6% for S, from 1.0 to 0.4% for P, from 3.3 to 6.2% for N, respectively. The results obtained give deep insight in obtaining high quality steels.
Influence of Ice Structure on Vitability of Frozen Sand-Water and Sand-Clay Mixtures
(Dnipro University of Technology, Dnipro, Ukraine, 2024) Solonenko, L. I.; Uzlov, Kostiantyn I.; Kimstach, Tetiana V.; Mianovska, Ya. V.; Yakymenko, D. Yu.
ENG: Purpose. To establish influence regularity of sand, water and clay preparation conditions on vitability of frozen mixtures made from combinations of these components and to increase the castings quality in foundries, as well as to improve technologies for artificial freezing of soils for underground constructions. Methodology. In this research, sand, clay, and water are used. Ice quality is estimated visually after water freezing at -15 °C in glass tubes. Frozen mixtures’ vitability at -15 °C is studied on beam-type samples. As indicators of survivability, the time to 1 mm bending of samples on supports and the time to their destruction are accepted. The time is recorded with a stopwatch, the temperature with an alcohol thermometer, the mass with electronic scales and the deflection arrow with a clock-type indicator. Findings. The presence and amount of water-soluble impurities in rare water significantly influence the nature, size and distribution of gas bubbles in ice, as well as frozen sand-water mixtures vitability. Frozen mixtures’ survivability increases with water content in them increasing, and, for sand  water mixtures, survivability is maximum if ice has a homogeneous structure. Among mixtures with clays, the mixture with non-swollen kaolin clay has the greatest vitability. Regarding survivability, recommendations for manufacturing products from frozen foundry mixtures have been developed. Originality. For the first time, deformation change kinetics (bending arrows) under the influence of beam-type samples’ self-mass from mixtures of quartz sand and water and quartz sand, clay and water frozen at -15 °C, which have been previously prepared in different ways, have been investigated. Insights into the influence of various factors and ice quality on the vitability of frozen mixtures have been further developed. Practical value. The obtained results can be useful for expanding ideas about natural frozen soils’ behavior during their cyclic temperature changes, soils artificially frozen during mine shafts elaboration, escalators’ and junctions’ tunnels, etc. when constructing subways. In foundries, the developed recommendations will reduce technological losses and will improve casting quality made using frozen casting molds and cores from sand-water or sand-clay-water mixtures, castings’ patterns and their pouring systems from sand-water mixtures.
Influence of K2ZrF6 and SiO2 on Refining Ability of Flux for Manufacturing Bimetallic Castings
(Latvia University of Life Sciences and Technologies, Jelgava, 2024) Aftandiliants, Yevhenii; Gnyloskurenko, Svyatoslav; Meniailo, Helena V.; Khrychikov, Valerii Ye.; Lomakin, Viktor
ENG: Bimetallic material is considered as an advanced functional material due to the unique physical and mechanical properties varied over the layers. Formation of bimetallic castings with steel base greatly depends on diffusion coupling with the second material working layer at elevated temperatures. The common technological problem is to remove the oxide films from the solid steel surface while its heating prior pouring melt of the working layer. This work studies the protective refining fluxes matching the selected requirements of good wetting the surfaces of solidified metal, effective protection against oxidation in the working temperature range, easy separation after pouring liquid metal and high refining capacity for oxides. The most effective fluxes based on Na2B4O7 and B2O3 compounds were used. To improve their ability to enhance wetting, work of adhesion and reduce surface decarbonization addition of K2ZrF6 and SiO2 to the flux in the amount of 3-4 wt.% was proposed and investigated. It was established that such additions increased wettability up to 9 and 20%, respectively and reduced the average rate of decarburization in the temperature range from 800 to 1000 ºС on 57 and 37%. The complete reduction of iron from scale on the steel surface was observed, while in the case of Na2B4O7 – B2O3 system it achieved 30-40% only. The mechanism explaining such a result is proposed to be due to the prevailing effect of zirconium in protecting the surface of the steel base from the oxidation and decarburization. The important result of the study is the recommendation of optimal flux composition (wt.%): Na2B4O7 – from 60 to 80; B2O3 – from 10 to 30; K2ZrF6 - from 3 to 4; SiO2 from 3 to 4. Thus, such flux could improve the production of steel based bimetallic castings and increase their properties.
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 P.; 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, Lyudmila I.; Repiakh, Serhii I.; Uzlov, Kostiantyn I.; Mamuzich, I.; Kimstach, Tetiana V.; Bilyi, Oleksandr P.
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.
Kinetics of Solidification and Crystallization of Liquid Axial Zone of Fe-C Alloys in Cylindrical Molds
(The Katowice Branch of the Polish Academy of Sciences, Poland, 2024) Khrychikov, Valerii Ye.; Semenov, Oleksandr D.; Aftandiliants, Y.; Gnyloskurenko, S.; Semenova, Tetіana V.; Meniailo, Helena V.
ENG: According to the results of digitization of the experimental studies carried out in the past concerning Fe-C alloys solidification in cylindrical molds of castings with a carbon content of 0.04%, 0.1%, 0.4%, 0.93%, 1.42%; 2.44%, 3.28%, 4.45%, 4.83% and their subsequent interpolation in the range of 0.04 ÷4.83%С there were obtained the curves of the advancement of the pour point, liquidus and solidus in the coordinates of the relative thickness of the solidified metal layer x/R and the parametric criterion τ/R2. Their usage is proposed for the development of modes of physical and chemical influence on the liquid metal in the axial zone of the casting after solidification of its calculated layer. Calculation of the mass of modifiers or deoxidizers for introduction into the axial zone was performed in relation to the total mass of metal in the liquid and liquid-solid zones of the casting. The technique for calculating the mass and time of introduction a graphitizing modifier into the axial zone of rolling rolls made of hypereutectoid steel with 1.7%C is proposed to reduce the negative impact of cementite, chromium and molybdenum carbides on the structure of the axial zone of the rolls. The obtained curves can also be used to assess the accuracy of computer modeling of the processes of Fe-C alloys solidification and further adaptation of mathematical models by the correction of thermophysical coefficients, the values of which are not always known in the liquidus-solidus temperature range.
Mechanical Properties and Structure of Cu-Al-Si-Sn-Mn System Non-Magnetic Cast Bronzes
(Dnipro University of Technology, Dnipro, 2026) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Repyakh, Serhii I.
ENG: Purpose. To establish regularity of Cu-Al-Si-Sn-Mn system non-magnetic corrosion-resistant bronze chemical composition on structure and mechanical properties complex influence and to determine its rational composition in terms of suitability for manufacturing products by casting methods. Methodology. For bronzes mechanical properties determination FP-100/1 technique and PSW-30 pendulum machine are used. Neophot-21 microscope is used to study microstructures. Chemical elements ratio in local areas of structural components determination is carried out with SEM-515 microanalyzer. Bronzes fracture surfaces fractographic analysis is performed visually and using Coxem EM-40 electron microscope. Bronzes relative magnetic permeability is measured with Magnetomat 1.790 magnetometer. Alloys chemical composition is determined using EXPERT 4L analyzer. Findings. It has been established that Cu-Al-Si-Sn-Mn system bronze suitable for casting in sand molds should contain by weight 6.0‒7.5 % Al, 1.0‒2.5 % Si, 0.21‒0.45 % Mn and 1.0‒2.2 % Sn, and alloying chemical elements ratio and inevitable impurities, according to the formula: KR = (1‒0.01 nn) (Al-Si-Mn)/(1 + Sn)2, should be equal to 0.42‒0.85. Bronze with KR > 0.85 is low-strength, but ductile and, therefore, mainly suitable for manufacturing products from it by deformation methods. Bronze with KR < 0.42 is low-strength and brittle and it is not suitable for manufacturing products by either casting or deformation methods. Originality. For the first time, Cu-Al-Si-Sn-Mn system bronzes alloying elements complex influence on their mechanical properties and structure formation features has been determined. Cu-Al-Si-Sn-Mn system aluminum bronzes with KR value from 0.42 to 0.85 mechanical properties levels increase with Cu-solid solution relative volume fraction in their structures decreasing, that is, with KR value increasing. Practical value. The data obtained can be used as a basis for new casting, corrosion-resistant non-magnetic bronzes development that have strength and density at the level of carbon steels or aluminum bronzes alloyed with nickel and iron.
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 V.; Bilyi, Oleksandr P.; 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.
Sand-Sodium-Silicate Mixtures Structured in Steam-Microwave Environment Effective Values of Thermo-Physical Properties
(Dnipro University of Technology, Ukraine, 2021) Solonenko, L. I.; Repiakh, Serhii I.; Uzlov, Kostiantyn I.; Dziubina, A. V.; Abramov, Serhii O.
ENG: Purpose. Sand-sodium-silicate mixtures, structured by steam-microwave solidification, thermo-physical properties integral-effective values during Al-Mg alloy and graphite cast iron pouring determination. Sand-sodium-silicate mixture apparent density changing according to quartz sand, cladded with sodium silicate solute, fractional composition and its influence on BrA9Zh3L bronze microstructure establishment. Methodology. Quartz sand with 0.23 mm average particle size, sodium silicate solute, aluminum alloy with 8.5 % Mg, flake graphite cast iron SCh200 (DSTU 8833:2019), bronze BrA9Zh3L (GOST 493-79) were used. Mixtures structuring was carried out in 700 W magnetron power microwave furnace. Sand-sodium-silicate mixture thermo-physical properties integral-effective values were calculated by G. A. Anisovich method, using castings results and molds thermography. Structured mixtures apparent density was determined on samples 50x120 mm dimension. Metallographic studies were realized using Neophot-21 optical microscope. Findings. It was found that with sodium silicate solute, used for sand cladding, amount increasing from 0.5 to 3 % mold material apparent density decreases and thermal activity lowers. This leads to castings grains size increasing. Mixture sodium silicate solute content was recommended limiting 1.5 % for fine-grained microstructure castings obtaining and cladded sand using, which particles pass through mesh side less 0.315 mm sieve. Sands with sodium silicate solute content more than 1.5 %, which don’t pass through sieve 0.4 mm mesh side, were recommended as casting molds heat-insulating material using. Originality. For the first time, when aluminum-magnesium alloy and graphite cast iron pouring, quartz sand cladded with sodium silicate solute in amount from 0.5 to 3.0 % (weight, over 100 % quartz sand), steam-microwave radiation structured, thermo-physical properties integral-effective values were determined. Practical value. Data obtained using will improve castings solidification time and rate analytical calculations accuracy, forecast level and residual stresses sign in them, shrinkage defects locations. This will reduce casting technology developing time and costs and castings manufacturability.
Si and Mn Effect on Mechanical Properties and Linear Shrinking of Non-Magnetic Cu-Al System Cast Bronzes
(Dnipro University of Technology, Dnipro, 2025) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Repyakh, Serhii I.
ENG: Purpose. To establish Si and Mn influence on mechanical properties level at 20 °C and aluminum bronzes structure with Al from 3 to 9 % mass content investigation. Methodology. Cast bronzes mechanical properties have been determined based on their fracture results on FP-100/1 machine and PSW-30 pendulum impactor. Microstructure has been examined using Neophot-21 optical microscope. Bronzes linear shrinkage coefficients have been calculated based on results of determining cast cylindrical samples lengths changes. Si and Mn complex influence on bronzes properties has been determined by the results of simplex triangles according to H. Scheffer plan constructing. Temperature has been measured with chromel-alumel thermocouple completed with electronic potentiometer. Bronzes chemical composition has been determined on EXPERT 4L analyzer. Findings. Silicon (up to 2 %) and manganese (up to 2 %) adding to Cu-Al system bronze, while aluminum content from 9 to 3 % reducing, leads to bronze ultimate tensile and yield strength decreasing during stretching and its plasticity increasing. At the same time, bronze structure, at any combination of Al, Si and Mn contents within their changes in studied limits, remains single-phase. Originality. For the first time, comprehensive assessment of influence of Si and Mn with simultaneous decrease in Al content on mechanical properties and linear shrinkage of Cu-Al-Si-Mn system cast bronzes has been carried out. It has been established that all bronzes of studied compositions have a single-phase structure and mechanical properties level that is inherent for pressure-worked bronzes. Practical value. The research results expand understanding about elemental and complex influence of Si and Mn on aluminum bronzes properties, provide an opportunity to choose a bronze with properties required level from its cast billet for deformation or to design castings taking into account the linear shrinkage values discovered in this work. The data obtained can also be the basis for new foundry, corrosion-resistant, non-magnetic bronzes, which have strength and density at the level of some carbon steel grades, development. Such materials have been used for parts that operate in chemically aggressive environments manufacturing, for control and measuring equipment and devices parts, for ship parts and naval devices, fittings, bushings, couplings, intrinsically safe tools, etc.
Step-by-Step Analysis of the Condition of the Side Tunnel for a Pylon-Type Metro Station under Construction NATM
(IOP Publishing Ltd, 2026) Radkevych, Anatolii V.; Kuprii, Volodymyr; Dubinchyk, Olha I.; Mazorchuk, Volodymyr F.
ENG: This scientific research provides a step-by-step analysis of the condition of the side tunnel for a pylon-type metro station with combined lining. An analysis of the algorithm for applying the New Austrian Tunneling Method to the construction of underground structures in hard rocks (as in the Dnipro Metro) has been conducted. It is justified that the analysis of the stress-strain state in the combined lining for the side tunnel of a station should be carried out in accordance with the stages of opening the working and installing the combined lining. A finite element model has been developed to represent the stages of side tunnel construction. This model also reflects the station structure’s conditions, its dimensions, and the interaction between the combined lining and the surrounding rock massif. The dependences of horizontal stresses in the rock massif and the bending moment in the combined lining on the stage of construction of the side tunnel have been obtained. The conclusion from the step-by-step analysis in the construction of the side tunnel for a pylon-type metro station, built using the New Austrian Tunneling Method, is that maximum stresses and force factors occur during construction rather than during the operational phase.
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.
Technogenic Hazards Coefficient of Sand-Resin Mixtures in Foundry Manufacturing
(Dnipro University of Technology, Dnipro, Ukraine, 2024) Solonenko, Lyudmila I.; Uzlov, Kostiantyn I.; Repiakh, Serhii I.; Prokopovich, I. V.; Bilyi, Oleksandr P.
ENG: Purpose. To carry out a comparative quantitative assessment of environmental and sanitary-hygienic hazards of utilizing synthetic resins for manufacturing molds and rods in foundry production. Methodology. Quarry quartz sand brand 1K2O202, furan resin brand Permaset 839 and catalyst Permacat 128, aluminum alloy AL2, gray cast iron SCh200, carbon steel 30L, bronze BrА9Zh3L were used in the work. Chromel-alumel thermocouples completed with electronic potentiometer were used for thermography. Molds were made from quartz sand, furan resin and catalyst mixture. Casting mold heating depth determination from casting to temperatures above 400 °C was carried out by its thermogram graphical processing, which was obtained after casting mold pouring with aluminum alloy, bronze, gray cast iron and carbon steel. Findings. Among those studied, the most dangerous are urea-phenol-formaldehyde, urea-formaldehyde and urea-furan resins, and the least dangerous are phenol-formaldehyde and phenol-formaldehyde-furan resins. Ecological and sanitary-hygienic hazard level when using resin mixtures increases with increasing resin amount in mixture, castings walls thickness, their surface area, as well as with increasing temperature of melt poured into the mold. Originality. For the first time, in relation to foundry molds and rods in foundry production manufacturing, technogenic hazard coefficient (THC) has been developed and its value has been calculated. This, in fact, is air volume (m3) containing maximum permissible concentration of carcinogenic or poisonous substances released as a result of mold organic binder material destruction when pouring aluminum alloy, bronze, cast iron or steel. Practical value. The use of the research results makes it possible to increase the level of predicting accuracy of technogenic (sanitary, hygienic and environmental) hazards, accuracy level of calculating ventilation systems capacities in foundries, taking into account the serial castings production, castings structural features, as well as binding materials nature for foundry molds and rods for such castings.
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 впливу різних середовищ на корозійну стійкість мідних сплавів
(Придніпровська державна академія будівництва та архітектури, Дніпро, 2021) Кімстач, Тетяна Володимирівна; Узлов, Костянтин Іванович; Реп’ях, Сергій Іванович; Солоненко, Людмила Ігорівна
UKR: Мета роботи – встановлення взаємозв'язку корозійних пошкоджень із хімічним складом, а також зовнішніми чинниками, що впливають на корозію міді і мідних сплавів у різних умовах експлуатації. Методика. Об’єкт аналізу – актуальна нормативно-технічна база даних щодо складів стандартних та перспективних сплавів на основі міді для експлуатації в умовах агресивних середовищ (атмосфери, газів, розчинів солей і лугів, водних середовищ). Застосовано метод зіставного аналізу з метою обґрунтування перспективи використання спеціальних бронз для виготовлення корозійностійких деталей машин і механізмів. Результати та їх обговорення. Проаналізовано поведінку мідних сплавів у різних умовах експлуатації і розглянуто фактори, що викликають їх руйнування. Показано взаємозв'язок корозійних пошкоджень із хімічним складом, а також зовнішніми чинниками, що викликають корозію. Наведено відомості про швидкість корозії мідних сплавів у різних середовищах. Розглянуто питання раціонального використання мідних сплавів стосовно до своєрідних умов роботи деталей і споруд. Наведено актуальну інформацію щодо проблеми підвищення надійності та довговічності роботи виробів із мідних сплавів, одним із методів вирішення якої бачиться цілеспрямований вибір матеріалу для їх виготовлення залежно від умов експлуатації. Практична значимість. За результатами досліджень у роботі обґрунтовано ефективні галузі використання технічної міді, латуней, олов’яних, крем’янистих, алюмінієвих, нікелевих бронз із точки зору особливостей їх опору корозійним пошкодженням. Висновки. Встановлено, що мідні сплави характеризуються високою корозійною стійкістю в різних середовищах. У морських і океанських середовищах корозійна стійкість алюмінієвих бронз перевершує в ряді випадків стійкість усіх інших мідних сплавів. Зазначено, що найбільшу корозійну стійкість серед мідних сплавів мають алюмінієві бронзи і мідно-нікелеві сплави.