Browsing by Author "Volkova, Olena"

Now showing 1 - 5 of 5

Public Metadata
GRK 2802: Densities, Surface Tensions, and Viscosities of Molten High-Silicon Electrical Steels with Different Silicon Contents
(Technische Universität Bergakademie Freiberg, 2025-10-24) Neubert, Lukas; Bellé, Matheus Roberto; Yamamoto, Taisei; Nishi, Tsuyoshi; Yamano, Hidemasa; Ahrenhold, Frank; Volkova, Olena
Density, surface tension, and viscosity of various liquid electrical steels are measured at different temperatures, varying in their silicon content between 3 and 6mass%. Density and surface tension are determined using the maximum bubble pressure method, while viscosity is investigated comparatively using a vibrating finger viscometer and an oscillating crucible viscometer. The results are compared with models known from the literature. Based on this, the density of the steel [ρ] = kgm 3 and the surface tension [σ] =Nm 1 can be described as a function of temperature [θ] = °C and silicon content [Si] =mass% using the equations: ρðθ, SiÞ ¼ 1.28 θ 104.18 Si þ 9081.8, σðθ, SiÞ ¼ 10 4 ½ 0.00903 θ2 1.21494 Si2 þ 29.268 θ 1.987 Si 22334 . There is a lack of experimental data in the literature for high-temperature thermophysical properties for electrical steels. This underlines once again the novelty and significance of this study, as the determined thermophysical properties are essential for a wide range of applications. For instance, they are crucial in the production of metallic powders for additive manufacturing by atomization to adjust the properties of the powders precisely. The findings are also important for steelmaking itself, as the corrosion behavior of refractory material can be better determined.
Public Metadata
GRK 2802: Effect of Oxygen on Thermophysical Properties of Molten High-Silicon Electrical Steels and Its Impact on Bubble Formation Behavior
(Technische Universität Bergakademie Freiberg, 2025-10-24) Neubert, Lukas; Bellé, Matheus Roberto; Seetharaman, Sridhar; Volkova, Olena
The presence of oxygen in liquid steels has a considerable influence on their properties. Higher oxygen concentrations are typical for unkilled melts, after tapping from the basic oxygen furnace (BOF) or during secondary metallurgy. This influences thermophysical properties, for instance, surface tension, due to the surface activity of dissolved oxygen. Processes in secondary metallurgy or the interaction of the melt with the refractory material will be different. In this study, density and surface tension of molten high-silicon electrical steels are analyzed dependent of different oxygen contents, which are comparable to industrial melts during secondary metallurgy. The maximum bubble pressure method was used, and total oxygen contents between 77 and 300 ppm were taken into consideration. The silicon content of the steels is varied between 3 and 6 mass-pct. The effect of oxygen on the bubble formation behavior during decarburization in a liquid steel melt is also discussed. The results make it possible to calculate the size of bubbles that form in a melt. These findings are transferred to the processing of electrical steels, to vacuum treatments like the RH or VOD process. Reactions such as decarburization and the dissolution behavior of alloying agents are described more precisely based on these insights.
Public Metadata
GRK 2802: Extraction of Vanadium from CaO–SiO2–MgO–Al2O3 Slags Based on Vaporization of Vanadium Pentoxide
(Technische Universität Bergakademie Freiberg, 2025-10-24) Neubert, Lukas; Shyrokykh, Tetiana; Tinkova, Nataliia; Seetharaman, Sridhar; Volkova, Olena
Vanadium is an important micro-alloying element for various steel grades. Consequently, it is also present in the slags used in the production of those grades. During steelmaking, the vanadium vaporization from the slag is not desirable, as it increases vanadium consumption and at the same time releases toxic vapors of its higher oxides. However, the recovery of vanadium from the slag after the processing is worthwhile. In oxidic form as vanadium pentoxide (V2O5), vanadium can be extracted from the slag. In this research, the vaporization behavior of vanadium from CaO–SiO2–MgO–Al2O3 industrial slag is investigated at 1873 K. The effect of different process parameters, e.g., the pressure in the furnace chamber, the duration of the oxygen treatment of the slag, and the oxygen flow rate, is considered. The effect of P2O5 and Fe2O3 addition on the extraction of vanadium is studied. It is possible to induce formation of V2O5 gas bubbles in the slag due to the oxidation of vanadium. Thus, vanadium respectively V2O5 is extracted from the slag.
Public Metadata
GRK 2802: Phosphorus Partition Between Liquid Crude Steel and High-Basicity Basic Oxygen Furnace Slags Containing V2O5
(Technische Universität Bergakademie Freiberg, 2025-10-24) Neubert, Lukas; Kovtun, Oleksandr; Kreschel, Thilo; Volkova, Olena
The influence of V2O5 on the phosphorus partition between liquid crude steel and heterogenous basic oxygen furnace (BOF) slag with CaO/SiO2 = 4.2 was investigated at a temperature of 1600 C in a middle frequency induction furnace. Thereby the phosphorus transfer from ‘‘steel to slag’’ as well as from ‘‘slag to steel’’ was studied over a holding time of 60 minutes. The measured results were shown as phosphorus partition and phosphorus capacity and compared with the experimental values from the literature. It was found that V2O5 in highly basic BOF slags decreases phosphorus partition and phosphorus capacity. In addition, the resulting slags were investigated using a scanning electron microscope (SEM).
Public Metadata
GRK 2802: Vaporization of Vanadium Pentoxide from Iron and Steel-Making Slags
(Technische Universität Bergakademie Freiberg, 2025-10-24) Neubert, Lukas; Volkova, Olena
Vanadium is present in increased amounts in slag because of the production of certain steel grades and manufacturing technologies. In terms of circular economy, vanadium should be recovered from the slag, to use it again as an alloying element. Only a few studies on the extraction of vanadium have been carried out with synthetic slags. The core of this study is the characterisation of the extraction behaviour of vanadium by evaporation of its oxides from real iron and steel-making slags. The effect of various influencing factors on the evaporation behaviour of the slags should be demonstrated. The evaluation of the results should also take crucible wear into account. In addition, the phases formed in the slag are to be analysed. For this purpose, several melting tests are carried out with different blast furnace slags. To determine the vaporised components, the slags are analysed by an X-ray fluorescence spectrometer.