Anton Yehorov

To clarify the structural role of CeO ₂ in CaO–Al ₂ O ₃ ‐based refining slag for rare‐earth microalloying high‐Al steel, the structural evolution and thermophysical properties of slags containing 0–18.21 wt.% CeO ₂ were investigated. The results reveal a dual structural effect associated with Ce‐containing species. Ce‐containing species act as network modifiers, weakening aluminate network connectivity and promoting the transformation of highly polymerized units into less polymerized species, thereby facilitating structural rearrangement. Simultaneously, Ce‐containing species are associated with higher‐coordinated Al–O environments and Ce‐related local coordination, while SEM–EDS reveals a tendency toward Ce–Ca–Al association during solidification, suggesting enhanced short‐range structural ordering and coordination stability. Accordingly, viscosity decreases with increasing CeO ₂ addition, reaching an approximately 33% reduction at 1650 °C with 18.21 wt.% CeO ₂ . In contrast, density, surface tension, and melting temperature increased by approximately 19%, 28%, and 78 °C, respectively, owing to enhanced local packing efficiency and structural stability. A composition–structure–property relationship is proposed, suggesting that viscosity is predominantly associated with long‐range network connectivity, whereas density, surface tension, and melting behavior are influenced by short‐range local coordination. These findings provide insight into the structural evolution of rare‐earth‐containing refining slags and offer a useful basis for understanding the composition–structure–property design of rare‐earth metallurgical slags.

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 SiO ₂ 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 SiO ₂ content at 1600°C reduced slag density and surface tension, increased viscosity, and shifted saturation from MgO to MgAl ₂ O ₄ 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‐SiO ₂ slag formed a dense, 195 µm‐thick MgAl ₂ O ₄ ‐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.

This work investigates the high‐temperature interactions between low‐sulfur Al‐killed Mn–B steel and carbon‐bonded magnesia (MgO–C) refractories containing 0 and 50 wt% recycled material (recyclates). Finger immersion tests are conducted at 1600 °C under an argon atmosphere, with variations in boron (B) and sulfur (S) content. Microstructural and chemical analyses via scanning electron microscopy/energy‐dispersive X‐ray spectroscopy reveal the formation of protective MgO and CaS layers at the steel–refractory interface, alongside spinel (MgAl ₂ O ₄ ) and calcium silicate phases. B and S jointly influence wetting and infiltration behavior, while increased S promotes thicker CaS layers. Recyclates introduce microstructural heterogeneity (distributed dissolution sites) but do not significantly alter the interfacial reaction mechanisms. Both refractories exhibit 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.

The interaction behavior between iron oxide‐bearing slags and carbon‐bonded MgO refractory (MgO‐C) containing calcium magnesium aluminate (CMA) was investigated at 1400°C, 1500°C, and 1600°C. After the iron oxide was reduced by the carbon from the MgO‐C refractory, a significant amount of MgO and metallic iron was observed to precipitate and disperse in the bulk of slag. During the iron oxide reduction process, the penetrative ability varied throughout the whole process, attributed to the effect of iron oxide on the thermophysical properties of the molten slag. No reduced iron was detected on the side of MgO‐C, which implies the slag penetration was primarily conducted after the iron oxide was reduced in the slag. Spinel was found to be predominantly formed during the interaction between MgO‐C refractory bearing CMA additive and slags, which strongly hindered further refractory corrosion. Additionally, the Ca ₃ Al ₄ MgO ₁₀ phase is predicted via ThermoCalc and XRD.

This study explores the thermophysical properties and crystallization behavior of two industrial 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 temperature-dependent viscosity with distinct break temperatures influenced by chemical composition. 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.

The current investigation delves into the oxidation resistance of magnesia‐carbon‐bonded (MgO‐C) refractory enhanced with calcium magnesium aluminate (CMA) cement, metallic aluminum, and Carbores P across a broad temperature spectrum from 800 to 1600 °C. The results demonstrate that the modification with CMA up to a temperature threshold of 1200 °C does not compromise the material's inherent oxidation resistance. However, above this temperature, a decrement in oxidation resistance is observed. The impact of grain size variation in CMA on the oxidation resistance of MgO‐C refractories is notable, and the finer grains show a superior performance. MgO‐C sample with Carbores P has excellent oxidation resistance up to 1000 °C, while above 1200 °C, its oxidation resistance strongly deteriorates. The metallic aluminum addition exhibits a remarkable oxidation resistance throughout the evaluated temperature range, indicated by a slight oxidation.