Browsing by Author "Yehorov, Anton"

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GRK 2802: Interaction of Ladle Slag With Varying SiO2 Content and Recyclate-Based MgO–C Refractories
(Technische Universität Bergakademie Freiberg, 2026-09-23) Yehorov, Anton; Salpagarov, Eldar; Mospan, Anhelina; Stadtmüller, Till Manon Jannis; Schemmel, Thomas; Aneziris, Christos G.; Volkova, Olena
Industrial MgO–C refractories fabricated from either pure fuzed magnesia (R0) or 50 wt% recycled MgO–C (R50) were exposed to ladle slags (C/A = 1) with varying SiO2 content (1–20 wt%). Wetting and infiltration behaviors were investigated using the sessile drop method at 1600°C under an Ar atmosphere for different dwell times. Quenched slag–refractory interfaces were characterized by SEM-EDX and compared with phase equilibrium simulations using FactSage 8.1. Increasing SiO2 content at 1600°C reduced slag density and surface tension, increased viscosity, and shifted saturation from MgO to MgAl2O4 spinel. During heating, R50 samples exhibited more intense gas formation. This delayed wetting and significantly slowed the initial stage of slag infiltration. Upon contact with recycled-based refractories, the high-SiO2 slag formed a dense, 195 μm-thick MgAl2O4-rich layer, entrapping residual calcium-silicate slag and serving as an in situ protective barrier against further oxidation and corrosion. These results demonstrate that well-processed MgO–C recyclate can inhibit slag attack, first by delaying infiltration via transient gas release, and subsequently by promoting a protective spinel layer under suitable slag compositions. Furthermore, the findings highlight the influence of substrate carbon content and open porosity on the slag’s melting and infiltration behavior.
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GRK 2802: Interactions between Molten High-Silicon Electrical Steels and Carbon-Bonded MgO Refractories Based on Recyclates
(Technische Universität Bergakademie Freiberg, 2026-05-29) Neubert, Lukas; Bellé, Matheus Roberto; Yehorov, Anton; Mospan, Anhelina; Stadtmüller, Till M. J.; Sridhar, Seetharaman; Aneziris, Christos G.; Volkova, Olena
In the present study a comprehensive investigation of the interactions between different molten high-silicon electrical steels (3 to 6 mass-% silicon) in aluminum killed condition with conventional and recycled MgO–C refractories is conducted. Immersion tests are carried out in accordance with the standards for testing and assessment of corrosion of refractories by liquids (DIN CEN/TS 15 418). Various mechanisms are defined and described which determine the corrosion of the refractory material in addition to infiltration. Scanning electron microscopy including energy dispersive X-ray spectroscopy (EDX analysis) is conducted to identify wear reactions, material transfers and reaction products at the contact zones and in the infiltration layers. The theoretically possible infiltration length is calculated and the limited applicability of the equations known from the literature is discussed. The formation of calcium sulfides and on other crucible reactions that take place are considered. These provide information and at the same time they influence the interactions between refractory materials and liquid steel.
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GRK 2802: Thermophysical Properties of Ladle Slag with Different SiO2 Content
(Technische Universität Bergakademie Freiberg, 2026-09-23) Yehorov, Anton; Volkova, Olena
The growing demand for electric vehicles, driven by global decarbonization policies, has led to an increase in the production of electric steel, which is characterized by a high silicon content. Producing this type of steel necessitates careful control of slag composition, particularly with high SiO2 content. This study investigates the thermophysical properties of cleanness slags with varying silicon oxide (SiO2) content, specifically examining viscosity, surface tension, and density. Silicon oxide, ranging from 1 to 20 wt%, was added to slags with a CaO/Al2O3 ratio of 1. The results show that increasing SiO2 content raises viscosity at temperatures above 1550 °C but reduces it at lower temperatures. Additionally, a linear decrease in density and surface tension was observed with increasing SiO2, which is attributed to the substitution of CaO with SiO2, thereby reducing the number of unsatisfied bonds in the slag network. Understanding these dynamics enhances control over slag-steel interactions in the steel ladle, ultimately improving process efficiency and steel quality.
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GRK 2802: Thermophysical Properties of the Desulphurization Slags With Various CaS and CaO/Al2O3 Ratio
(Technische Universität Bergakademie Freiberg, 2026-09-25) Salpagarov, Eldar; Bellé, Matheus Roberto; Yehorov, Anton; Richter, Julia; Volkova, Olena
Low sulphur content is essential for high-quality steels and can be achieved by using desulphurization slag. During the desulphurization process the chemical composition of the slag changes leading to alteration in its thermophysical properties, such as surface tension, viscosity, and density. However, the influence of CaS on these thermophysical properties is poorly investigated nowadays. In this study, the influence of various CaS content (0-10 wt%) and CaO/Al2O3 ratio (1.87-1.36) on the viscosity, surface tension, and density of desulphurization slags is investigated. Measurements of surface tension and density are carried out using the maximum bubble pressure method, while viscosity is determined using the rotating bob method. The obtained results show that a decrease in viscosity value is observed with an increase in CaS content only up to 6 wt%, however, further addition of CaS sharply increases viscosity. In case of surface tension and density measurements, an increase in CaS content up to 10 wt% results in a reduction of both property values. Additionally, to study microstructure differences of the investigated slags, they were quenched and examined using Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX).
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GRK2802: Characterization of Thermophysical Properties and Crystallization Behavior of Industrial Mold Fluxes
(Technische Universität Bergakademie Freiberg, 2026-04-27) Bellé, Matheus Roberto; Yehorov, Anton; Chebykin, Dmitry; Zotov, Dmytro; Volkova, Olena
This study explores the thermophysical properties and crystallization behavior of two in-dustrial Mold Fluxes (MF1 and MF2) used in continuous steel casting. Viscosity, density, and surface tension were measured using the Rotating Bob Viscometry (RBV) and the Maximum Bubble Pressure (MBP) method, while crystallization dynamics were assessed via the Single Hot Thermocouple Technique (SHTT). Both fluxes showed tempera-ture-dependent viscosity with distinct break temperatures influenced by chemical compo-sition. MF1 had higher viscosity and activation energy (127.72 kJ mol−1) than MF2 (112.11 kJ mol−1) due to its higher Al2O3 content. Density and surface tension decreased linearly from 1523 to 1623 K, with values of 2642–2618 kg m−3 and 299–291 mN m−1 for MF1, and 2708–2656 kg m−3 and 348–305 mN m−1 for MF2. Crystallization analysis showed that MF1 required higher cooling rates (critical cooling rates: 21 K s−1 vs. 18 K s−1 for MF2) for glass formation, highlighting its greater glass-former content.
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GRK2802: Interaction Between Molten Al-Killed Mn-B Steel and Carbon-Bonded MgO Refractories Based on Recyclates
(Technische Universität Bergakademie Freiberg, 2026-04-29) Bellé, Matheus Roberto; Neubert, Lukas; Yehorov, Anton; Stadtmüller, Till Manon Jannis; Aneziris, Christos Georgios; Volkova, Olena
This work investigates the high-temperature interactions between low-sulfur Al-killed Mn-B steel and carbon-bonded magnesia (MgO-C) refractories containing 0 wt% and 50 wt% recycled material (recyclates). Finger immersion tests (FIT) were conducted at 1600 °C under an argon atmosphere, with variations in boron (B) and sulfur (S) content. Microstructural and chemical analyses via SEM/EDX revealed the formation of protective MgO and CaS layers at the steel-refractory interface, alongside spinel (MgAl2O4) and calcium silicate phases. B and S jointly influenced wetting and infiltration behavior, while increased S promoted thicker CaS layers. Recyclates introduced microstructural heterogeneity (distributed dissolution sites) but did not significantly alter the interfacial reaction mechanisms. Both refractories exhibited comparable performance in forming protective layers, suggesting that recyclate-containing MgO-C materials can serve as sustainable alternatives without compromising thermochemical stability or steel cleanliness. These findings support the use of recycled materials in refractory manufacturing, contributing to waste reduction and circular economy practice in steelmaking.
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GRK2802: Non-metallic Inclusion Evolution in Interaction of Al-killed Mn-B Steel with Desulfurization Slag and MgO-C Refractories Containing Environmentally Friendly Binders and Recyclates
(Technische Universität Bergakademie Freiberg, 2026-05-20) Bellé, Matheus Roberto; Neubert, Lukas; Yehorov, Anton; Kerber, Florian; Gunasekar, Dinesh Kumar; Salpagarov, Eldar; Aneziris, Christos G.; Volkova, Olena
The high-temperature interaction between Al-killed Mn-B steel, desulfurization slag, and carbon-bonded magnesia refractories containing conventional, environmentally friendly binders and recyclate systems was systematically investigated using finger immersion testing at 1600 °C for 30 minutes. Chemical analysis of steel and slag, combined with SEM/EDX characterization of refractory/steel/slag interfaces and non-metallic inclusions (NMIs), was performed to interpret reaction mechanisms and the evolution of inclusions. Significant slag modification occurred during testing, characterized by MgO enrichment, CaO and Al2O3 depletion, and the formation of Fe- and Mn-bearing oxides. In the steel, pronounced decarburization, sulfur increase, boron depletion, and enhanced oxygen and nitrogen contents were observed, indicating reoxidation and interfacial reactions. Independent of refractory condition, MgAl2O4 spinel and Ca2SiO4 phases were detected in the infiltrated refractory zone. Refractories containing recyclates and alternative binders chemically modified the inclusion population and significantly increased NMI number density, particularly Mn-Si-Ti-based inclusions. The results demonstrate that refractory composition strongly influences slag chemistry, inclusion characteristics, and steel cleanliness. These findings provide a new understanding of refractory-slag-steel interactions during secondary metallurgy and highlight the need for optimized slag/refractory formulations to ensure inclusion control and steel quality under increasingly sustainable material strategies.