CaO MgO Al2O3 SiO2 Research Articles

Study on the surface activity of t-YSZ nanomaterials by first-principles calculation

The internal mechanism underlying the high surface activity of t-YSZ nanomaterials composed of low Miller index facets is not completely understood at present. Using first-principles calculations, the surface energies, as well as geometrical and electronic properties of t-YSZ morphology are simulated and analyzed by conventional bulk surface and new microfacet models. The results show that the surface energies follow the trend Esurface [(0 1 0 × 0 1 0)] > Esurface [(1 1 1 × 0 1 0)] > Esurface [(1 0 1 × 0 1 0)] > Esurface [(1 1 1 × 1 0 1)] > Esurface [(1 0 1 × 1 0 1)] > (1 1 1) bulk surface > (1 0 1) bulk surface > (0 1 0) bulk surface, where the surface energies of the microfacet models are several times greater than those of the bulk surfaces. The surface activity of the microfacet is therefore much more vigorous than that of the bulk surface. The very high chemical activity of the microfacets is derived from their large Fermi energy, pseudo energy gap, and change in Mulliken population. Although the low Miller index surfaces exhibit weak activity, their interface, such as [(0 1 0 × 0 1 0)], have high chemical activity, because of which they are easily and quickly corroded by CaO-MgO-Al2O3-SiO2 (CMAS), as confirmed by experimental reports. Hence, our findings can be considered a first and vital step toward understanding the unusual properties of nano-YSZ.

Effects of Na<sub>2</sub>O and B<sub>2</sub>O<sub>3</sub> Addition on Viscosity and Electrical Conductivity of CaO–Al<sub>2</sub>O<sub>3</sub>–MgO–SiO<sub>2</sub> System

Effects of Na<sub>2</sub>O and B<sub>2</sub>O<sub>3</sub> Addition on Viscosity and Electrical Conductivity of CaO–Al<sub>2</sub>O<sub>3</sub>–MgO–SiO<sub>2</sub> System

Comparison of CMAS corrosion and sintering induced microstructural characteristics of APS thermal barrier coatings

The microstructural features of high-temperature sintered and CaO-MgO-Al2O3-SiO2 (CMAS) corroded air plasma sprayed Y2O3 stabilized ZrO2 (YSZ) thermal barrier coatings (TBCs) under the thermal gradient condition were comparatively studied. As-sprayed YSZ has a lamellar structure and the lamellae are composed of closely aligned columnar crystals. The sintered and the CMAS corroded YSZ coatings maintain the t’-ZrO2 phase as the as-sprayed YSZ coating. The sintered YSZ remains the lamellar structure with reduced interlamellar gaps and grains coarsening. After the CMAS corrosion, the top layer of the YSZ coating keeps its lamellar structure consisting of some columnar grains with the CMAS infiltration into the intergrain gaps and the formation of striped Zr2Y2O7. The typical lamellar structure transforms into more equiaxed grains in the middle and bottom layers of the ceramic coating along with significant infiltration of amorphous CMAS and anorthite formation in the bottom layer owing to the high contents of Ca and Al.

CaO‐MgO‐Al2O3‐SiO2 corrosion behavior of air‐plasma‐sprayed (LaxYb1−x)2Zr2O7

AbstractThe CaO‐MgO‐Al2O3‐SiO2 (CMAS) corrosion of thermal barrier coatings (TBCs) is a crucial problem for the lifetime of blades and vanes of jet engine and gas turbine at high operating temperature. Although many new alternative materials for TBCs have been developed in recent years, their application is limited by the CMAS corrosion. On the other hand, the composition difference of CMAS between regions makes solving this problem very difficult. Therefore, in this study, the yearly composition changes of sand‐dust around Beijing area were investigated. The high‐temperature corrosion behavior of air‐plasma‐sprayed 8YSZ and newly developed (LaxYb1−x)2Zr2O7 TBCs by the representative sand‐dust of Beijing was investigated. In comparison, a universally used CaO‐riched composition of simulated silicate deposit was also adopted for the TBCs corrosion test. It is found that the (LaxYb1−x)2Zr2O7 TBCs performs much better anti‐corrosion behavior than that of 8YSZ, both by Beijing sand‐dust and simulated one. Particularly, Yb2Zr2O7 TBCs appear to be the optimum material against silicate deposits attack. The mechanism of silicate deposits corrosion has also been discussed.

Analysis of basic network structure of continuous casting mould powder in electromagnetic field

ABSTRACTIn the continuous casting process, the mould powder plays the role of insulator and heat insulator in the crystallizer, prevents molten steel from oxidizing, absorbs non-metallic inclusions, and controls lubrication and heat transfer between the casting billet and the mould. It is an important functional material that promotes the quality of a billet and ensures that the continuous casting process proceeds smoothly. Here in we analyse the changes in the microstructure of the protective flux from the aspect of the infrastructure of the flux slag. Additionally, using the classical molecular dynamics simulation method, the structure of the CaO–SiO2–Al2O3–MgO slag system was simulated in the presence of magnetic fields of various strengths. The magnetic field was found to have the following effects on the slag structure. The participation of the basic elements Si, Al, O, etc. in bond formation is independent of magnetic field strength. The magnetic field causes changes in the peaks, coordination numbers, and peak widths of the radial distribution functions of bonds such as Si–O, Al–O, and Mg–O. The greater the magnetic field strength, the more disordered the ionic clusters are, and the greater is the decrease in slag viscosity. Although the effect of the magnetic field influences the structure of the slag, there is not much change in the way the molecules and atoms are stacked in the slag.

Structure-based viscosity model development for titania aluminosilicate slags

ABSTRACTBased on the structure of melts, a model has been developed that estimates the viscosity of the fully liquid melts in the CaO–MgO–Al2O3–SiO2–TiO2 systems. Three kinds of tetrahedral ([SiO4]4−, [AlO4]5−, and [TiO4]4−) are considered in the titania aluminosilicate slag. According to the hole theory of melts, this model provides a link between the viscosity and the structures of the melts. The present model is capable of predicting the viscosities in the CaO–MgO-–Al2O3–SiO2–TiO2 systems with wide composition and temperature ranges above liquidus; the average of relative errors for this model was approximately 20.0%. From the model calculation results, the addition of TiO2 decrease the viscosity of slag under non-reducing atmosphere. The ability of increasing viscosity follows the order: SiO2> Al2O3> TiO2> CaO. Due to the charge compensation and unit size effect, the replacement of TiO2 by Al2O3 will result in the increase of viscosity.

Effect of CaF2 on viscosity, structure and properties of CaO-Al2O3-MgO-SiO2 slag glass ceramics

Bayan Obo tailings (BOTs), fly ash (FAS), and stainless-steel slag (SSS) are industrial wastes that require reasonable, clean, and effective utilization for environment protection. The paper focuses on the structure and properties of glass-ceramics that were prepared by melting BOT, FAS, and SSS raw materials. The effect of CaF2 on the viscosity, structure, and performance of CaO-Al2O3-MgO-SiO2 (CAMS) slag glass-ceramics is determined by viscometer, differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and physicochemical properties measurements. The results show that moderate amounts of CaF2 facilitates depolymerization of the silicate networks, which leads to a decrease in the melting temperature, viscosity and viscous activation energy of glass. However, the content of more than 3% CaF2 results in a dramatic decreases in the chemical stability of the glass-ceramics because of the transformations of the main crystalline phase from diopside to anorthite, which is accompanied by fluorite precipitation.

Pressure-induced preferential grain growth, texture development, and anisotropic properties of Fe/augite matrix composites prepared by spark plasma sintering

Fe/augite matrix composites were prepared by spark plasma sintering (SPS) using CaO–MgO–Al2O3–SiO2 glass-ceramic water quenched slag as the raw material and Fe2O3 and Fe-75%Si as additives. The phase compositions and microstructures of the samples were analyzed by x-ray diffraction and scanning electronic microscopy. The effect of the texture on the microstructure and mechanical properties of the Fe/augite matrix composites was investigated. The results show that the high-density sample fabricated by SPS at 800 °C has a fiber texture along the c axis such that is parallel to the compression direction. The Fe/augite matrix composite prepared at a sintering temperature of 800 °C has better properties than that prepared at 700 °C, with density of 3.52 g cm−3, Vickers hardness of 7.73 GPa, and fracture toughness of 12.09 M P a ·m 1/2.

Experimental and thermodynamic analysis of MgO saturation in the CaO–SiO2–Al2O3–MgO slag system melted in a laboratory resistive furnace

Slags from the CaO–SiO2–Al2O3–MgO system (CSAM) are commonly employed for the secondary refining treatment of special steels. Those slags must be designed to work in the refining reactions, presenting properties that maximize their capability to capture impurities from the liquid steel. With this in context it becomes relevant to study the phases of those slags in the operating temperatures. In the present study, four slags from the CSAM system, with increments of MgO (5.98–23.43wt.%) and binary basicity (1.96–2.48), were melted in a high temperature resistive electric furnace. The objective was to analyze the phases present in the slags in secondary refining temperatures (1500°C (1773K) to 1600°C (1873K)), depending on their chemical composition. Fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy (SEM) with dispersive energy spectrometer (EDS) were used for the slag analyses. The experimental results were compared with thermodynamic calculations obtained by using the FactSage™ 7.1. As the MgO contents increased in the slag (>14.96wt.%), the precipitation of MgO solids were predicted by thermodynamic calculations, indicating the saturation of the slag in this compound. In the SEM/EDS analysis, this saturation was confirmed by the presence of dark and dendritic phases rich in MgO in the slag microstructure. However, for MgO contents up to 7.93wt.%, the microstructures obtained were mainly composed of C2S (dicalcium silicate) phases dispersed in the liquid matrix, identifying the unsaturated condition for the MgO compound.

Effect of BaO and Na2O on the viscosity and structure of blast furnace slag

ABSTRACTThe effects of BaO and Na2O on the viscosity and structure of CaO–SiO2–MgO–Al2O3-based blast furnace slag were investigated using the rotating cylinder method and Raman spectra technique in this work. The results indicated that the slag viscosity first increased and then decreased with the addition of BaO and decreased with the increasing content of Na2O. When adding BaO into CaO–SiO2–MgO–Al2O3 slag, Ba2+ ion could compensate Al3+ ion and form more complex aluminate or aluminate–silicate structures, which increased the degree of polymerisation and the viscosity of the slag. With the further addition of BaO, the content of SiO2 decreased and the relative content of O2− ion increased, which may slightly depolymerise the slag structure then decreased the viscosity. When adding Na2O into CaO–SiO2–MgO–Al2O3–BaO slag, Na2O may act as network modifiers which could simplify the complex silicate structures and lower the polymerisation degree of slags, therefore decreased the viscosity.

Effect of Fly Ash on the Properties of Ceramics Prepared from Steel Slag

In this study, SiO2–Al2O3–CaO–MgO steel slag ceramics containing 5 wt % MgO were used for the preparation of ceramic bodies, with the replacement of 5–20 wt % quartz and feldspar by fly ash. The effect of the addition of fly ash on the sintering shrinkage, water absorption, sintering range, and flexural strength of the steel slag ceramic was studied. Furthermore, the crystalline phase transitions and microstructures of the sintered samples were investigated by XRD, Fourier transform infrared (FTIR), and SEM. The results showed that the addition of fly ash affected the crystalline phases of the sintered ceramic samples. The main crystal phases of the base steel slag ceramic sample without fly ash were quartz, diopside, and augite. With increasing fly ash content, the quartz diffraction peak decreased gradually, while the diffraction peak intensity of anorthite became stronger. The mechanical properties of the samples decreased with the increasing amount of fly ash. The addition of fly ash (0–20 wt %) affected the optimum sintering temperature (1130–1160 °C) and widened the sintering range. The maximum addition amount of fly ash should be 15 wt %, for which the optimum sintering temperature was 1145 °C, water absorption was 0.03%, and flexural strength was 43.37 MPa higher than the Chinese national standard GBT 4100-2015 requirements.

Evolution of metamorphic fluid recorded in granulite facies metacarbonate rocks from the middle segment of the Mogok metamorphic belt in central Myanmar

AbstractThe Mogok metamorphic belt of Palaeogene age, which records subduction‐ and collision‐related events between the Indian and Eurasian plates, lies along the western margin of the Shan plateau in central Myanmar and continues northwards to the eastern Himalayan syntaxis. Reaction textures of clinohumite‐ and scapolite‐bearing assemblages in Mogok granulite facies metacarbonate rocks provide insights into the drastic change in fluid composition during exhumation of the collision zone. Characteristic high‐grade assemblages of marble and calcsilicate rock are clinohumite+forsterite+spinel+phlogopite+pargasite/edenite+calcite+dolomite, and scapolite+diopside+anorthite+quartz+calcite respectively. Calculated petrogenetic grids in CaO–MgO–Al2O3–SiO2–H2O–CO2 and subsets of this system were employed to deduce the pressure–temperature–fluid evolution of the clinohumite‐ and scapolite‐bearing assemblages. These assemblages suggest higher temperature (>780–810°C) and [=CO2/(CO2+H2O) >0.17–0.60] values in the metamorphic fluid for the peak granulite facies stage, assuming a pressure of 0.8 GPa. Calcite grains commonly show exsolution textures with dolomite particles, and their reintegrated compositions yield temperatures of 720–880°C. Retrograde reactions are mainly characterized by a reaction zone consisting of a dolomite layer and a symplectitic aggregate of tremolite and dolomite grown between clinohumite and calcite in marble, and a replacement texture of scapolite by clinozoisite in calcsilicate rock. These textures indicate that the retrograde reactions developed under lower temperature (<620°C) and (<0.08–0.16) conditions, assuming a pressure of 0.5 GPa. The metacarbonate rocks share metamorphic temperatures similar to the Mogok paragneiss at the peak granulite facies stage. The values of the metacarbonate rock at peak metamorphic stage are, however, distinctly higher than those previously deduced from carbonate mineral‐free paragneiss. Primary clinohumite, phlogopite and pargasite/edenite in marble have F‐rich compositions, and scapolite in calcsilicate rock contains Cl, suggesting a contrast in the halogen compositions of the metamorphic fluids between these two lithologies. The metamorphic fluid compositions were probably buffered within each lithology, and the effective migration of metamorphic fluid, which would have extensively changed the fluid compositions, did not occur during the prograde granulite facies stage throughout the Mogok metamorphic belt. The lower conditions of the Mogok metacarbonate rocks during the retrograde stage distinctly contrast with higher conditions recorded in metacarbonate rocks from other metamorphic belts of granulite facies. The characteristic low conditions were probably due to far‐ranging infiltration of H2O‐dominant fluid throughout the middle segment of the Mogok metamorphic belt under low‐amphibolite facies conditions during the exhumation and hydration stage.

Effects of oxygen atmosphere, FeOx and basicity on mineralogical phases of CaO–SiO2–MgO–Al2O3–FetO–P2O5 steelmaking slag

ABSTRACTThe mineralogical phase of slag after crystallisation is essential to utilisation of steelmaking slag. The mineralogical phases of cooled multicomponent CaO–SiO2–MgO–Al2O3–FetO–P2O5 slag with different iron oxide contents and basicities (defined as the ratio of mass percentage of CaO to mass percentage of SiO2 (w(CaO)/w(SiO2))) in different atmospheres were investigated in the present work by scanning electronic microscopy and energy dispersed spectroscopy analysis and X-ray diffraction. The mineralogical phases in steelmaking slag cooled in argon are mainly nCa2SiO4-Ca3(PO4)2 (thereafter nC2S-C3P) solid solution, (Fe, Mn, Mg)O (RO) phase. Some CaMgSiO4 phases could be found in slag with lower basicity. The mineralogical phases in steelmaking slag cooled in air are mainly nC2S-C3P solid solution, spinel phase. The overall crystallisation of slag cooled in both argon and air was enhanced with increasing basicity. However, the crystal sizes become smaller in sample with high basicity. The Fe-enriched phases were transformed from non-faceted RO phase in sample cooled in argon to faceted spinel phases in sample cooled in air. The crystallisation of slag cooled in both argon and air was promoted with increasing FeOx content. The phosphorus content in solid solution was elevated with decreasing basicity and increasing FeOx content. It was implied by the present work that appropriate basicity and air oxidation would be beneficial to magnetic separation and phosphorus utilisation.

Thermodynamic Simulation of the Influence of the Temperature and the Basicity of a Boron-Containing Slag on Steel Desulfurization

The results of thermodynamic simulation of the desulfurization of a medium-carbon steel by slags of the CaO–SiO2–MgO–Al2O3–B2O3 system are presented. The HSC Chemistry 6.12 software package is used for the simulation. The thermodynamic simulation is performed for 20 various chemical compositions of slags with various B2O3 contents (1–4%)1 and basicities ((CaO)/(SiO2) = 2–5). The computations are performed using the Equilibrium Compositions module in the temperature range from 1500 to 1700°C with an increment of 50°C at a gas phase pressure of 0.1 MPa. The main results of the calculations are presented as the dependences of the change in the sulfur content in steel [S] on the temperature, the content of B2O3, and the slag basicity. An increase in the temperature of metal desulfurization from 1500 to 1700°C exerts a favorable effect on the sulfur content for the studied range of slag basicities. In particular, the sulfur content in steel decreases from 0.012 to 0.009% when steel is processed with the slag having 3% B2O3 and a basicity (CaO)/(SiO2) = 2. A positive effect of an increase in the slag basicity from 2 to 5 on metal desulfurization is observed: the degree of desulfurization increases from 61.1 to 97.2% at 1600°C and 3% B2O3 content in the slag. As the B2O3 content in a slag increases from 1 to 4%, its refining properties decrease significantly in the range of basicity not higher than 2. In the range of high slag basicities (3–4), the negative effect of acidic oxide B2O3 on the refining properties of the slag decreases, providing low sulfur contents (which do not exceed [S] = 0.003–0.004% at 4% B2O3). At a slag basicity of 5, the sulfur content in steel decreases to 0.001%, all other things being equal. The simulation results can be used for the calculation of steel desulfurization processed by slags containing B2O3.

Sulfide Capacities in the Al2O3–CaO–MgO–SiO2 System

In the present study, the sulfide capacities of the slags in the ternary Al2O3–CaO–SiO2 system at 1873 K, and in the quaternary system Al2O3–CaO–MgO–SiO2 at 1823 and 1873 K are experimentally measured using copper–slag equilibrium at controlled oxygen partial pressure. The experimental data, which has been unavailable, are needed for the improvement of a sulfide capacity model. An assessment of the available data for sulfide capacities in the Al2O3–CaO–MgO–SiO2 system and its sub lower‐order systems are made. Based on this assessment and the present experimental results, the model parameters of the existing sulfide capacity model are re‐optimized. The sulfide capacity model can be successfully used in the prediction of the sulfide capacities of multicomponent slags with satisfactory accuracy.

Structure and Crystallization of Alkaline-Earth Aluminosilicate Glasses: Prevention of the Alumina-Avoidance Principle.

Aluminosilicate glasses are considered to follow the Al-avoidance principle, which states that Al-O-Al linkages are energetically less favorable, such that, if there is a possibility for Si-O-Al linkages to occur in a glass composition, Al-O-Al linkages are not formed. The current paper shows that breaching of the Al-avoidance principle is essential for understanding the distribution of network-forming AlO4 and SiO4 structural units in alkaline-earth aluminosilicate glasses. The present study proposes a new modified random network (NMRN) model, which accepts Al-O-Al linkages for aluminosilicate glasses. The NMRN model consists of two regions, a network structure region (NS-Region) composed of well-separated homonuclear and heteronuclear framework species and a channel region (C-Region) of nonbridging oxygens (NBOs) and nonframework cations. The NMRN model accounts for the structural changes and devitrification behavior of aluminosilicate glasses. A parent Ca- and Al-rich melilite-based CaO-MgO-Al2O3-SiO2 (CMAS) glass composition was modified by substituting MgO for CaO and SiO2 for Al2O3 to understand variations in the distribution of network-forming structural units in the NS-region and devitrification behavior upon heat treating. The structural features of the glass and glass-ceramics (GCs) were meticulously assessed by advanced characterization techniques including neutron diffraction (ND), powder X-ray diffraction (XRD), 29Si and 27Al magic angle spinning (MAS)-nuclear magnetic resonance (NMR), and in situ Raman spectroscopy. ND revealed the formation of SiO4 and AlO4 tetrahedral units in all the glass compositions. Simulations of chemical glass compositions based on deconvolution of 29Si MAS NMR spectral analysis indicate the preferred formation of Si-O-Al over Si-O-Si and Al-O-Al linkages and the presence of a high concentration of nonbridging oxygens leading to the formation of a separate NS-region containing both SiO4 and AlO4 tetrahedra (Si/Al) (heteronuclear) in addition to the presence of Al[4]-O-Al[4] bonds; this region coexists with a predominantly SiO4-containing (homonuclear) NS-region. In GCs, obtained after heat treatment at 850 °C for 250 h, the formation of crystalline phases, as revealed from Rietveld refinement of XRD data, may be understood on the basis of the distribution of SiO4 and AlO4 structural units in the NS-region. The in situ Raman spectra of the GCs confirmed the formation of a Si/Al structural region, as well as indicating interaction between the Al/Si region and SiO4-rich region at higher temperatures, leading to the formation of additional crystalline phases.

Study on the Interfacial Reactions between an Fe–Mn–Si Alloy and Complex Oxides Containing FeO during Isothermal Heating

To precisely control the characteristics of complex oxides by heat treatment, the effect of FeO on the interfacial reactions that occur between an Fe–Mn–Si alloy and CaO–SiO2–Al2O3–MgO–MnO–FeO oxide was studied and clarified. Eight types of diffusion couples with different compositions of oxides were produced using a confocal scanning laser microscope (CSLM). The morphologies of the alloy–oxide interfaces and the changes in their chemical compositions with isothermal heating at 1273 and 1473 K for 10 h were investigated. A modified dynamic calculation model was established and verified to achieve better understanding on the interfacial reaction mechanism between the Fe–Mn–Si alloy and the multicomponent oxide with different FeO content during isothermal heating. The results showed that during isothermal heating at 1273 and 1473 K, “solid–solid” and “solid–liquid” alloy–oxide reactions occurred in the A-1-x and A-2-x diffusion couples, respectively. The interfacial alloy–oxide reactions were enhanced by increasing the initial FeO content in the oxide and the heating temperature. The particle precipitation zone (PPZ), Mn-depleted zone (MDZ) and Si-depleted zone (SDZ) widths in the A-1-x and A-2-x diffusion couples after heating also showed a positive correlation with the increase in the initial FeO content in the oxide, as well as the size and number of MnO·SiO2 inclusions. The diffused oxygen from the oxide reacting with elemental Mn and Si in the alloy plays a dominant role in the A-1-x diffusion couple during heating, whereas for A-2-x, the dominant reaction is between elemental Si in the alloy and MnO in the oxide.

Chemical 3D-imaging of glass inclusions from allende (CV3) olivine via SIMS: A new insight on chondrule formation conditions

Natural glass inclusions - hosted in Mg-rich olivines from Allende (CV3) type I chondrules - and synthetic melt inclusions - trapped in forsterite crystallized from CMAS (CaO-MgO-Al2O3-SiO2) melts - were mapped by Secondary Ion Mass Spectrometry (SIMS) for CMAS major oxides. The first ever 3D chemical images of extra-terrestrial glass inclusions were obtained, along with chemical depth profiles for each oxide. Results show similar patterns for both synthetic glass inclusions (trapped in olivine formed by slow crystallization in a magmatic liquid) and natural inclusions from Allende's olivines. No incompatible-rich boundary layer or diffusion pattern was observed in either case. The absence of an incompatible-rich boundary layer suggests that the olivine overgrowth surrounding glass inclusions in Allende's olivines was formed during slow cooling of the host olivine and likely the surrounding chondrule. This provides new constraints on the cooling rates of type I chondrules.

Effect of cooling regime on phase transformation and chromium enrichment in stainless-steel slag

ABSTRACT Cooling regime of stainless-steel slag has a great influence on the migration rule of chromium. Effect of cooling rate on chromium distribution in CaO–SiO2–MgO–Al2O3–Fe x O–Cr2O3 system has been studied by FactSage, XRD and SEM-EDS in this paper. Results showed that the main phases in stainless-steel slag are spinel, bredigite, wustite, lime and periclase. Chromium was enriched in the stable phases. With the decrease in cooling rate, the size of chromium-rich phase increased relatively while chromium content in spinel phase reduced. Rapid cooling was favourable to the chromium enrichment in spinel phase in high basicity (high than 2.0) stainless-steel slag.

Modeling reoxidation behavior of Al–Ti-containing steels by CaO–Al2O3–MgO–SiO2 slag

A kinetic model was developed using FactSage Macro Processing to simulate the reoxidation of Al–Ti-containing steels by CaO–Al2O3–SiO2–MgO slags. The calculated results show a good agreement with the experimental data. Thus, the developed kinetic model can be used to predict changes in slag, steel, and inclusion compositions during the reaction process. During the slag reoxidation process, the reactions occurring at slag–steel interface and in the bulk steel were confirmed to be the reduction of SiO2 by [Al] and [Ti] and the self-dissociation of SiO2 into [Si] and [O]. Increasing the ratio of CaO to SiO2 in the slag can significantly suppress the self-dissociation of SiO2 in the slag and lower the amount of inclusions produced during reoxidation. The formed inclusions changed from solid Al2O3 to Al2O3–TiO x inclusions, which was mainly dependent on the w([Al]) and w([Ti]). The amount of inclusions was obviously influenced by the composition of the top slag.