Burbelko, Andriy A.
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Item type:Article, Access status: Open Access , An evaluation of combustion kinetics for the synthesis reaction of the reinforcing phase during casting(AGH University of Science and Technology Press, 2020) Wiktor, Tomasz; Sobula, Sebastian; Burbelko, Andriy A.; Ptasznik, MichałThe computer modeling of the solidification process in castings with local composite reinforcement (LCR) obtained as a result of in situ reactions of self-propagating high temperature synthesis (SHS) is difficult due to limited data on the thermo-physical parameters of exothermic effects and the kinetics of the synthesis reaction. In the present study, Hadfield cast steel casting was manufactured with LCR containing titanium carbide particles obtained in situ by the SHS method. Reaction kinetics of titanium carbide synthesis in the composite casting were determined on the basis of temperature measurements in the area of LCR during the process. For the estimation of the reaction, the Fourier Thermal Analysis method was used. The paper presents the results of temperature measurement and the results of the calculation of SHS reaction kinetics. It was found that the reaction time under the conditions of the analyzed casting is below 3 s.Item type:Article, Access status: Open Access , Determination of the Heat Transfer Coefficient in the Isothermal Quenching Process of ADI Cast Iron Cooled with Water Mist(Akademia Górniczo-Hutnicza, 2026) Burbelko, Andriy A.; Stręk, PiotrIsothermal quenching of austempering cast iron (ADI) castings requires that, after austenitization the casting must be rapidly cooled to the temperature of isothermal austenite decomposition. The cooling rate throughout the entire volume of the heat-treated product must be high enough to prevent pearlitic transformation. At the same time, the temperature of the cooled surface must not decrease below the martensitic transformation start temperature Ms. The cooling rate of the casting surface is determined by factors such as the temperature difference between the surface of the cooled casting and the cooling medium, the thermal conductivity of cast iron, the heat transfer coefficient, and the wall thickness of the treated casting. In the case of cooling with water mist, the heat transfer coefficient depends on the temperature of the cooled surface. To control the cooling process of castings using water mist, information about this relationship for the temperature range of 200–800°C is needed. Available scientific publications on this subject contain contradictory data. Therefore, a measuring station was built with the ability to set the temperature of the cooled surface. The station includes a measuring system that allows the measurement of the heat flux flowing from the heating element into the environment. The result of the research is the measurement of the relationship between the temperature of the cooled surface and the heat transfer coefficient. The values obtained will be used in the future to build a numerical model of ADI castings heat treatment. This work may contribute to the future replacement of salt baths (currently used for fast cooling and austempering) with water mist spraying. In this case, the low-temperature operation of austenite decomposition can be performed without the use of salt a bath.Item type:Article, Access status: Open Access , Derivation of equations for a size distribution of spherical particles in non-transparent materials(AGH University of Science and Technology Press, 2021) Gurgul, Daniel; Burbelko, Andriy A.; Wiktor, TomaszThis paper presents a new proposition on how to derive mathematical formulas that describe an unknown Probability Density Function (PDF$_{3}$) of the spherical radii ($r_{3}$) of particles randomly placed in non-transparent materials. We have presented two attempts here, both of which are based on data collected from a random planar cross-section passed through space containing three-dimensional nodules. The first attempt uses a Probability Density Function (PDF$_{2}$) the form of which is experimentally obtained on the basis of a set containing two-dimensional radii ($r_{2}$). These radii are produced by an intersection of the space by a random plane. In turn, the second solution also uses an experimentally obtained Probability Density Function (PDF$_{1}$). But the form of PDF$_{1}$ has been created on the basis of a set containing chord lengths collected from a cross-section. The most important finding presented in this paper is the conclusion that if the PDF$_{1}$ has proportional scopes, the PDF$_{3}$ must have a constant value in these scopes. This fact allows stating that there are no nodules in the sample space that have particular radii belonging to the proportional ranges the PDF1.Item type:Article, Access status: Open Access , New computer method of derivative thermal express analysis of cast iron for operational prediction of quality of melts and castings(AGH University of Science and Technology Press, 2019) Zaharčenko, Eduard Volodimirovič; Sirenko, Ekaterina; Gončarov, Oleksandr; Bogdan, Oleksandr; Burbelko, Andriy A.; Kawalec, MagdalenaThis method is based on the determination of similarity criterion $\overline{Z}$ as the average temperature difference between the reference and analyzed curves in the solidification region. The purpose of this work is to describe the thermal express-analysis (TDA) device created by us and the substantiation of the reliability and sensitivity of the results of the new method, including the definition of a two-sided confidence interval using Student's t-test. The error of the method was determined with the Student's criterion taken into account. The high sensitivity of the method to the metallurgical prehistory of the gray and white cast iron melts was confirmed. The method has been successfully tested under laboratory and experimental-industrial conditions on induction melting cast iron. The new method uses a disposable environmentally friendly submersible steel sampler with a heat-resistant coating inside and out. The method allows for the quick adaptation to the conditions of specific foundries (especially with the frequent changes of classes and types of cast iron) due to replenishing the database of the reference samples. The basic features of the new method are its universality, self-adaptability, speed, relative simplicity, and high sensitivity to the metallurgical prehistory of molten iron.Item type:Article, Access status: Open Access , A diffusion model of binary systems controlled by chemical potential gradient(AGH University Press, 2022) Wróbel, Marek; Burbelko, Andriy A.The paper presents a model of diffusion in a single phase with chemical potential gradient as the driving force of the process. Fick's laws are strictly empirical and the assumption that the concentration gradients are the driving forces of diffusion is far from precise. Instead, the gradient of chemical potential $\mu_{i}$ of component i is the real driving force. The matter of governing equations of models that incorporate this approach will be raised and discussed in this article. One of more important features is the ability to acquire results where diffusion against the concentration gradient may occur. The presented model uses the Finite Difference Method (FDM) and employs the CALPHAD method to obtain chemical potentials. The calculations of chemical potential are carried out for instant conditions - temperature and composition - in the entire task domain by Thermo-Calc via a TQ-Interface. Then the heterogeneity of chemical potentials is translated into mass transfer for each individual element. Calculations of two modelling tasks for one-dimension diffusion field were carried out. First: isothermal conditions with linear initial composition distribution and second: constant temperature gradient with uniform chemical composition in the specimen. Results for two binary solid solutions: Fe-C and Fe-Si, in the FCC phase for the given tasks will be presented. Modelling allows us to estimate the time needed to reach a desired state in a particular equilibrium or quasi-equilibrium state. It also shows the path of the composition change during the process. This can be used to determine whether the system at some point is getting close to the formation of another phase due to significant deviation from its initial conditions.Item type:Article, Access status: Open Access , The Occurrence of Chunky Graphite in Ductile Cast Iron Solution Strengthened by Silicon(AGH University Press, 2025) Zaczyński, Artur; Królikowski, Maciej; Sokolnicki, Marek; Nowak, Adam; Guzik, Edward; Burbelko, Andriy A.Solution strengthened ferritic cast iron is characterised in EN 1563:2018 (and also in ISO 1083:2018) as grades EN-GJS-450-18, EN-GJS-500-14 and EN-GJS-600-10. Machine and plant builders have been using this material in new designs since 2011. The strength and ductile properties, competitive in comparison with the previous classical ductile cast iron grades, make it pos¬sible to reduce the weight of castings. Particularly preferred is grade EN-GJS-600-10 with Rm min. 600 MPa and A min. 10%. Strengthening of the ferritic matrix is possible due to the content of approximately 4.2% of silicon in the cast iron. In casting practice, this material is difficult to produce in a stable manner due to the frequent occurrence of degenerate chunky graphite in the casting structure, resulting in a loss of ductile properties of the cast iron. In this article, an analysis has been made, based on literature, of the occurrence of strong negative segregation of silicon in classical ductile cast iron. The authors’ own research has confirmed the occurrence of chunky graphite in the cast. Dendritic crystallisation of austenite and strong segregation of silicon favours the formation of chunky graphite. A much stronger proportion of silicon was found in the chunky graphite zone, compared to the adjacent ball graphite zone. The introduction of micro-additives into the liquid melt eliminated the presence of chunky graphite in the casting. The applied modifiers of graphite and metal matrix (hybrid modification) seem to be an effective method to stabilise the technological process of this innovative casting material.