Browsing by Author "Selivorstov, Vadim Yu."

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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.
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.
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.