Increasing MgO Content Research Articles

Tailoring the Structural and Optical Properties of Oxychloride Magnesium Tellurite Glass with the Addition of Samarium Ions

In this study, samarium-doped oxychloride magnesium tellurite glass with composition (79−x)TeO2−xMgO−20Li2O−1Sm2O3 (Series 1) and (79−x)TeO2xMgCl2−20Li2O−1Sm2O3 (Series 2) with 0 ≤ x ≤ 15 mol% was prepared by the melt-quenching technique. The structural and optical properties of synthesized samples were investigated, and the XRD results dictated an amorphous nature for both samples. The glass density of both Series 1 and 2 decreased with increasing MgO and MgCl2 content. However, the molar volume behaves in a completely opposite manner to an increase in MgO or MgCl2 content. FTIR spectra revealed from the vibrational wavenumber shift of TeO4 and TeO3 structural units showed a significant rise in HOH vibration mode, which implies its usefulness in boosting water and light absorption. Four absorbance bands were observed via UV-Vis NIR, while the indirect optical band gap around (3.42–3.36) eV and (3.42−3.30) eV for Series 1 and Series 2 were observed from UV-Vis spectroscopy. The emission spectra from the photoluminescence study revealed four distinct bands centered at 562.54, 599.14, 645.63 and 708.40 nm which are attributed to the transition from 4G5/2 – 6HJ/2 (J = 5,7,9,11) of states of Sm3+. The optimum glass with a composition of TeO-MgO 15% demonstrates a high potential for optical device development.

Effect of MgO on solidification crystallisation behaviour of high SiO2 content MnO–SiO2–Al2O3-based inclusions in Si–Mn-killed steel

Aiming at avoiding the formation of high-hardness crystalline phase in inclusions, the effect of MgO on the solidification crystallisation behaviour of high SiO2 content MnO–SiO2–Al2O3-based inclusions was investigated. The results showed that the high SiO2 content MnO–SiO2–Al2O3 inclusions precipitated the pure SiO2 phase during the solidification process. With the increase of MgO content in inclusions, the content of the SiO2 phase decreased continuously, while the MgSiO3 phase began to precipitate and the content increased gradually. Besides, 20 wt.% MgO content inclusions first precipitated the Mg2SiO4 phase, and the MgSiO3 phase was formed in the subsequent solidification process. Thermodynamic calculation results indicated that the beginning of crystallisation temperature first decreased and then increased with the increase of MgO content in inclusions. However, the calculation results were partially different from the experiment results, because inclusions became the undercooling system during solidification and led to crystallisation hysteresis. The increase of MgO content in inclusions decreased the content of bridging oxygen and resulted in the depolymerisation of complex network structures, which promoted the crystallisation of inclusions. Moreover, the crystalline phase formed in inclusions transformed along the route of “SiO2 phase–MgSiO3 phase–Mg2SiO4 phase” with the increase of MgO content in inclusions.

Crystallization Behavior of the CaO–SiO2–Al2O3–MgO System Inclusions

The crystallization process of low melting point CaO–SiO2–Al2O3–MgO system inclusions during the continuous casting and hot rolling process greatly affects the deformability of inclusions. The effect of Al2O3 and MgO contents on the crystallization characteristics of CaO–SiO2–Al2O3–MgO system melts representing the typical oxide inclusions in Si–Mn deoxidized steels is systematically investigated. The continuous cooling transformation and time–temperature transformation experiments are carried out. The results reveal that the increase of Al2O3 contents restrains the crystallization process of the melt, whereas the crystallization tendency of the melt is promoted with the increase of MgO contents. The precipitated phases are predominately 2CaO·MgO·2SiO2 and 3CaO·MgO·2SiO2, and the primary crystalline phase is unaffected by the changes of Al2O3 and MgO contents. To obtain low melting point plasticized inclusions with limited crystallization ability, it is recommended to control the Al2O3 and MgO contents greater than 15 wt% and below 5 wt%, respectively. The isothermal treatment is suggested to be controlled within a proper temperature range (1175–1250 °C) to decrease the crystallization kinetics. The oxide system's viscosity change is the limiting kinetic factor in the crystallization process, and it can be utilized to predict the system's crystallization tendency.

Effect of MgO addition on the structural evolution, crystallization and properties of self-glazed ceramics sintered from granite sludge

Recycling of granite sludge has both economic and environmental benefits. In this paper, high glossiness self-glazed ceramics were prepared from granite sludge with the addition of TiO2, Ca(OH)2 and MgO by combining two-step sintering and low-temperature crystallization. The effect of MgO addition on the phase evolution, crystallization and properties of the glazed ceramics was studied to reveal its role in the diopside precipitation. With increasing MgO content, the reduced glass viscosity accelerates the dissolution of quartz and anorthite into the liquid glass phase, resulting in a decrease in flexural strength above 1 % MgO. Meanwhile, the addition of MgO increases the non-bridging oxygen to lower the glass transition temperature. The increase in the Al/Si ratio of the glass phase and the mixed alkaline earth effect contribute to an increase in the crystallization temperature. After thermal treatment at 950 °C, the precipitated diopside increases the crystallinity of the glazed glass-ceramic from 6.4 % to 19.3 % at 3 % MgO, resulting in a surface glossiness of 99.7 GU and a flexural strength of 64.1 MPa. High glossiness self-glazed ceramics with an aesthetic appearance could be used in decorative building tiles for scalable utilization of granite sludge.

Transport property mechanism of semiconducting x MgO:(50-x) PbO:50V2O5 glasses

ABSTRACT The electrical properties of semiconducting Oxide glasses with composition x MgO(50-x) PbO:50V2O5 glasses have been investigated. The glasses were prepared by the normal melt quenching technique. The X-ray diffractograms of the present glass system show that the prepared glass samples are perfectly amorphous. The DSC patterns indicate that the MgO-substituted glass samples behave like the eutectic composition up to x = 15 mol%. The DC conductivity is measured in the temperature range of 300 to 500 K, and data are fitted with Mott’s and Schnakenberg models. The conductivity of all the glass compositions increases with increasing MgO content. The conduction mechanism of these glasses was non-adiabatic. The various parameters, such as activation energy, average site separation between transition metal ions and polaron radius, have been calculated and found consistent with Mott’s small polaron hopping non-adiabatically between different sites. The Hruby parameter (kg) for this glass system has been calculated and discussed.

Microstructure, Thermal and Mechanical Properties of AlN-MgO Composites Prepared by Spark Plasma Sintering

AlN-MgO composites with different compositions were prepared by spark plasma sintering, and the effects of their composition on their microstructure, thermal properties, and mechanical properties were systemically investigated. MgO compositions in the AlN-MgO composites were controlled from 20 to 80 wt%. The results indicated that a phase transition did not occur during the sintering process, and different solid solutions were formed within the MgO and AlN lattices. The AlN-MgO composites exhibited finer-grain microstructures than those of the sintered pure AlN and MgO samples. Transmission electron microscopy analysis showed that both oxygen-rich, low-density grain boundaries and clean boundaries with spinel phases were present in the composites. The sintered pure AlN sample exhibited the highest thermal conductivity (53.2 W/mK) and lowest coefficient of thermal expansion (4.47 × 10<sup>-6</sup> /K) at 100 °C. And, the sintered pure MgO sample exhibited moderate thermal conductivity (39.7 W/mK) and a high coefficient of thermal expansion (13.05 × 10<sup>-6</sup> /K). With increasing MgO contents in the AlN-MgO composites, however, the thermal conductivity of the AlN-MgO composites decreased, from 33.3 to 14.9 W/mK, while their coefficient of thermal expansion generally increased, from 6.49×10<sup>-6</sup> to 10.73×10<sup>-6</sup> /K with increasing MgO content. The composite with an MgO content of 60 wt% exhibited the best mechanical properties overall. Thus, the composition and microstructure of AlN-MgO composites have a determining effect on their thermal and mechanical properties.

Corrosion of MgO–C refractories by vanadium slag with high MgO content

Due to the limitation of the subsequent process for producing V2O5, the converter of vanadium extraction needs to use the slag with high MgO content to splash slag. This paper focus on the corrosion behavior of vanadium slag with high MgO content on MgO–C refractory. Corrosion experiment, SEM-EDS analysis, XRF analysis, and theoretical calculation are utilized to study the interface and mass transfer between slags and refractory. The results indicate that the average width of the reaction interface decreases from 9.3 μm to 3 μm with the increase of MgO content from 2 wt% to 8 wt%. When the corrosion time increases from 15 min to 60 min, the average width of the reaction interface decreases from 9 μm to 5 μm, and stabilizes at 5 μm as the corrosion continues. The mass transfer coefficient of MgO rises to 0.663 × 10−2 cm s−1 in the first 60 min of corrosion time, and then falls to 0.592 × 10−2 cm s−1 as the corrosion continues to 120 min. The mass transfer coefficient of MgO also shows an increasing trend with the increase of temperature and rotation speed. When the temperature increases from 1445 °C to 1490 °C, the mass transfer coefficient of MgO increases from 0.1313 × 10−2 cm‧s−1 to 1.4556 × 10−2 cm‧s−1. When the rotation speed increases from 10 rpm to 30 rpm, the mass transfer coefficient of MgO increases from 0.411 × 10−2 cm s−1 to 0.818 × 10−2 cm s−1.

Ternary system rock salt Li3NbO4–Li2TiO3–MgO microwave dielectric ceramics with low loss for resonator antenna applications

A novel type of Li3NbO4–Li2TiO3-xMgO (LLMx, x = 1–5) ceramics were prepared using the solid-state reaction method. When the sintering temperature is between 1180 °C and 1300 °C, the solid solution ceramics with cubic rock salt structure are obtained. As the MgO content increases, the εr value decreases, the τf value is basically constant, and Q×f exhibits ideal dielectric properties at x = 4 (εr = 15.26, Q×f = 119,456 GHz (f = 9.97 GHz), τf = −35.9 ppm/°C). The Raman spectrum analysis was used to examine and understand the vibration mode and intrinsic mechanism of dielectric properties in ceramics. Additionally, a dielectric resonant antenna based on LLM4 ceramic is fabricated with a resonant frequency of 7.23 GHz (|S11| = −45.6 dB), a higher gain and broadband width of 501 MHz.

Effect of MgO content in refining slag on the non-metallic inclusions in tire cord steel

In order to weaken the corrosion of refractory during the refining process of tire cord steel, the MgO content in the low basicity (w(CaO)/w(SiO2)≈1.0) slags was increased from 7.9% to 12.6% in industrial experiments. The evolution and removal of inclusions during the refining process were investigated, and the slag properties were also measured in laboratory. It is found that during the refining process, the contents of Al2O3 and CaO generally climb in the inclusions, and SiO2 and MnO contents drop accordingly. Even though, the increase of MgO contents in the refining slag has no obvious effect on the evolution trend and the final composition of inclusions. Therefore, the plasticity of inclusions would not be evidently influenced. On the other hand, with the increase of MgO content in slags, the viscosity and surface tension of the refining slags decrease, while the melting point and the melting rate increase. Due to the lower viscosity and surface tension, a higher MgO content in the slag is beneficial for the removal of inclusions in steel. So, a suitable increase of MgO content in the refining slags is suggested considering the melting point of the slag.

Fluid-metasomatized rocks with extremely low δ26Mg values in subducted oceanic lithosphere: Implications for mantle Mg isotope heterogeneity and the origin of low-δ26Mg magmas

The subduction of oceanic slabs with diverse lithologies greatly contributes to the geochemical heterogeneity of the mantle. Oceanic metasomatism leads to the formation of rocks with heterogeneous geochemical characteristics, which can be further modified by fluid–rock interactions during subduction zone processing. Investigations of exhumed high-pressure oceanic rocks not only shed light on the compositional variations that occur during oceanic metasomatism and subduction processes but also help in understanding mantle heterogeneity and magma genesis. Here, we present a comprehensive Mg–O–Sr–Nd isotope study on eclogite-facies Mg- and Ca-metasomatized rocks (Ti-clinohumite dikelets and metarodingites, respectively) and their host meta-serpentinites from the Voltri Massif (Ligurian Western Alps). Compared to their Fe–Ti gabbroic protoliths, the Ti-clinohumite (Ticl) dikelet and metarodingite are characterized by high MgO contents (∼32–38 wt%) and CaO contents (∼17–25 wt%), respectively. These Mg- and Ca-enriched rocks both display low δ26Mg values of −0.54 ‰ to −0.43 ‰ and −1.49 ‰ to −0.82 ‰, respectively, while the serpentinite hosts have mantle-like δ26Mg values of −0.26 ‰ to −0.20 ‰. The Ticl-chlorite rind rimming the metarodingite has a low δ26Mg value of −1.00 ‰. No carbonate minerals were found for metasomatized rocks that have low δ18O values ranging from +2.0 ‰ to +3.4 ‰, demonstrating that their low δ26Mg signature cannot be attributed to metasomatism by fluids involved with carbonate components. The increase in MgO content and decrease in δ26Mg in the Ticl dikelets are ascribed to fluid-induced mass transfer through low-δ26Mg fluids buffered by serpentinization of the host ultramafic rocks. The metarodingite has comparable MgO but extremely low δ26Mg values compared to those of the gabbroic protolith. By integrating reported Mg isotope data for low-grade rodingites, we propose that the low δ26Mg values of metarodingites are ascribed to isotopic exchange with serpentinizing fluids during progressive rodingitization reactions at the seafloor. However, the extremely low δ26Mg value of the Voltri metarodingite (as low as −1.49 ‰) may be attributed to further metasomatic modification in the subduction zone. High pressure metamorphic recrystallization of these metasomatized rocks play a limited role in their Mg isotope compositions. Therefore, our results show that the oceanic metasomatized metarodingite and Ticl-bearing dikes hosted in serpentinite display systematically low-δ26Mg features. Such isotopically light Mg compositions can be preserved during subduction to eclogite-facies conditions. Hence, subduction of these metasomatized rocks may lead to the transfer of a low-δ26Mg component into the deep mantle, which was overlooked thus far and may further contribute to the origin of low-δ26Mg magmas.

Phase transition mechanism and long‐term stability of LiF‐assisted sintered Li2MgxZrO3+x microwave dielectric ceramics

AbstractHerein, Li2MgxZrO3+x (x = 0–1) +2 wt.% LiF ceramics with a rock salt structure were prepared by the solid‐state reaction method. The phase transition mechanism was systematically investigated by X‐ray diffraction, and first‐principles calculations. With a gradual increase in MgO content, the samples underwent a monoclinic‐Li2ZrO3 to tetragonal‐Li2ZrO3 to tetragonal‐Li2MgZrO4 to cubic‐phase transition. The variations of the microwave dielectric properties due to the phase transition were systematically analyzed by the multi‐phase mixtures law. In addition, CO2 adsorption of the samples was quantitatively analyzed by X‐ray photoelectron spectroscopy, and the long‐term stability of the Q × f of the samples was investigated. The optimal microwave dielectric properties were obtained in Li2Mg0.2ZrO3.2 ceramic at 950°C: εr = 19.5, Q × f = 44 500 GHz, and τf = 2.6 ppm/°C. In addition, the ceramic samples were compatible with Ag, which indicates that Li2MgxZrO3+x (x = 0−1) +2 wt.% LiF is a promising material for low‐temperature co‐fired ceramics.

Microstructure evolution, mechanical characteristics and erosion behavior of Cr2O3–Al2O3–MgO–ZrO2 refractories in molten reduction slag

In order to overcome the serious corrosion problem of furnace hearth refractory materials for smelting reduction ironmaking, the Cr2O3–Al2O3–MgO–ZrO2 refractories were synthesized, and the phase component, microstructure, mechanical characteristics, and slag erosion behavior of composite refractories were investigated and evaluated. The results indicate that the composite refractories mainly consist of Mg(Al, Cr)2O4 spinel phase, (Al, Cr)2O3 solid solution and ZrO2. The content of Mg (Al, Cr)2O4 spinel significantly increases with the increasing MgO content, while the content of (Al, Cr)2O3 obviously decreases. Furthermore, the comprehensive mechanical properties of the MgO modified composite refractories can be obviously enhanced by increasing the MgO content, and sample S4 presents the best mechanical characteristics when the MgO addition is 10 wt%. The corresponding hardness, compressive strength and bending strength are 14.22 GPa, 267.14 MPa and 80.0 MPa, respectively. This is mainly because the formation of Mg(Al, Cr)2O4 significantly improves the densification of composite refractories, and a large number of high-strength Mg (Al, Cr)2O4 spinel “bridge” formed between the large-sized (Al, Cr)2O3 grains. The erosion test results indicate that increasing the MgO content can significantly improve the slag infiltration resistance of composite refractories, because the formation of Mg (Al, Cr)2O4 spinel layer significantly improves the densification of MgO reinforced composite refractories. Although the slag corrosion resistance of Mg(Al, Cr)2O4 is lower than that of (Al, Cr)2O3, the Cr2O3–Al2O3–MgO–ZrO2 refractories still presents good erosion resistance, permeability resistance, and excellent mechanical characteristics.

Chemical surface modification for the preparation of MgO cladding to enhance magnetic properties of Fe-Si-Nb-B-Cu nanocrystalline soft magnetic composites

This study employed chemical synthesis and decomposition techniques to fabricate MgO insulation coating on the surface of nanocrystalline soft magnetic powder. It was found that this coating effectively suppresses the time lag effect in the magnetization process of soft magnetic materials under high-frequency alternating magnetic fields, consequently reducing the overall losses of soft magnetic composite materials by mitigating the time-dependent effects during magnetization. Specifically, at an MgO content of 0.8 wt%, the power losses of nanocrystalline soft magnetic composite materials decreased from 519.13 kW/m3 and 3665.78 kW/m3 to 277.69 kW/m3 and 2718.3 kW/m3 respectively, under alternating magnetic fields with magnetic induction strengths of 20 mT and frequencies of 1 MHz and 3 MHz. The MgO insulation coating effectively mitigated the relaxation phenomenon in the dynamic hysteresis loops of nanocrystalline soft magnetic composite materials within dynamic magnetic fields, reducing the adverse effects of internal eddy currents in high-frequency alternating magnetic fields, thereby confirming the close relationship between magnetic hysteresis losses and eddy current losses in soft magnetic composite materials. Additionally, with the increase in MgO content, there was a significant improvement in the quality factor of nanocrystalline soft magnetic composite materials, showing a decreasing trend in the imaginary part of the complex permeability, which reflects the magnitude of power losses. Furthermore, the positive response of MgO coating in enhancing DC superimposition performance and reducing inductance impedance values has been validated, underscoring its crucial role in improving the stability of circuit systems.

Study on properties of CaF2–CaO–Al2O3–MgO–B2O3 electroslag remelting slag for rack plate steel

Abstract The loss of boron (B) in the rack plate steel during the electroslag remelting process has a significant impact on its mechanical properties. Therefore, it is necessary to design appropriate slags to suppress the loss of B. CaF2–CaO–Al2O3 phase diagram was calculated to determine the basic slag. The influence of MgO and B2O3 on the performance of the basic slag was studied to determine the optimal amount of MgO addition. The equilibrium reactions between rack plate steel and the 50.48 mass% CaF2–24.81 mass% CaO–24.71 mass% Al2O3–2 mass% MgO-y mass% B2O3 (y was 1–10) slag were studied to examine the variation in B content in the steel. Results indicate the presence of a temperature-qualified eutectic point in the CaF2–CaO–Al2O3 phase diagram. With an increase in MgO content in the slag, the melting temperature of the basic slag initially decreases and then increases, while the electrical conductivity decreases. On the other hand, B2O3 reduces the melting point of the slag and increases the equilibrium B content in the steel. The 50.48 mass% CaF2–24.81 mass% CaO–24.71 mass% Al2O3–2 mass% MgO-y mass% B2O3 (y was 5–7) slag can achieve the target range of B content in the steel, and its viscosity meets the requirements of electric slag remelting.

Effects of MgO doping concentration on densification and microstructure of flash sintered α-Al2O3 ceramics

The effects of MgO doping concentration on the sintering behavior of Al2O3 ceramics in flash sintering were studied. The relative density, grain size and oxygen vacancies of the flash sintered samples doped with different amounts of MgO were characterized. The results showed that the relative density and grain size increased with MgO concentration up to 0.25 wt%, and then decreased with further increasing MgO content. These were coincident with the changes in oxygen vacancies in the flash-sintered samples. Flash sintering behaviors of 0.25 wt% MgO doped Al2O3 disc were different from those in conventional sintering, where the grain growth was inhibited when the MgO content is 0.25 wt%. The results can be explained by the fact that the higher oxygen vacancies in the flash sintered sample than that in the conventional sintered one, due to the applied electric field/current in flash sintering enhancing the solubility of MgO in Al2O3.

Phase composition and liquidus temperatures of the CaO–SiO2–MgO-13 wt%Al2O3–TiO2 system in reduction conditions

Effects of TiO2, binary basicity and MgO content on the liquidus temperatures of TiO2–CaO–SiO2–MgO–Al2O3 slags were experimentally studied in equilibrium with carbon. The experimental techniques include high temperature equilibration, quenching and Electron Probe X-ray Microanalysis (EPMA). It was found that the major primary phase in the composition range investigated is M3O5 (M = Ti, Mg, Al). The liquidus temperatures increase with increasing TiO2 and MgO contents, whereas decrease with increasing CaO/SiO2 mass ratio. The experimentally determined liquidus temperatures are much higher than the predicted ones by FactSage and the primary phases between the experiment results and predictions are also different. The mole fractions of Al2TiO5 and Ti3O5 in the M3O5 phase decrease, but MgTi2O5 increases with increasing MgO content and CaO/SiO2 in the samples. Moreover, the proportions of Al2TiO5 and MgTi2O5 in the M3O5 phase decrease, while Ti3O5 proportion in the M3O5 phase increases with increasing the reaction time. The mole ratio of Ti3+/Ti4+ in the M3O5 phase decreases with MgO content and CaO/SiO2 mass ratio in the samples but increases with increasing reaction time.

An experimental study on the phase equilibria of the CaO–MgO–SiO2–13%Al2O3–50%TiO2 system in air at 1450 °C

This study systematically investigates the phase equilibrium relations of the CaO–MgO–SiO2–13%Al2O3–50%TiO2 system in air at 1450 °C. Within the composition range, the coexistence of the liquid phase with anosovite and rutile, liquid-rutile (TiO2), liquid-anosovite (M3O5), liquid phase with anosovite and spinel, liquid-spinel, liquid phase with perovskite and spinel, and liquid-perovskite (CaTiO3) were found. Additionally, the 1450 °C isotherm in this system was obtained by comparing the experimental liquid phase results with the predicted results by FactSage 8.1. The experimental findings indicated that an increase in MgO content contributed to a higher concentration of MgTi2O5 in the anosovite solid solution. Notably, the predicted liquidus temperature was much lower than the experimentally determined liquidus temperatures within the primary of M3O5 and spinel area. This work would contribute to further refining the phase diagram of the titania-containing systems.

The phase evolution of resin‐bonded Al2O3‐Al refractory containing magnesia under N2‐blowing

AbstractPhenolic resin‐bonded Al2O3‐Al‐MgO refractories were prepared from sintered alumina and aluminum as raw materials, adding 3 wt%, 9 wt% and 15 wt% high‐purity magnesia. The green samples were treated at 200°C and heated at 1300°C and 1600°C in a nitrogen atmosphere. The results showed that the phases after heating at 1300°C were α‐Al2O3, spinel solid solution (MgAlON), Al4O4C, Al4C3 and unreacted aluminum. The phases after heating at 1600°C were α‐Al2O3, spinel solid solution (MgAlON), Al4O4C, Al4C3, (Al2OC)x(AlN)1‐x solid solution, Al8O3N6, and unreacted aluminum, with a tendency to shift from Al‐O‐C to MgAlON with increasing MgO content. MgAlON was obtained by in situ synthesis of MgO, Al2O3, Al, and N2 at 1300°C. With sufficient magnesia, the stability of Al4O4C and Al4C3 decreases at 1600°C, and AlON is formed with better stability and can be solubilized into MgAlON. That is, when magnesia was added to the phenolic resin‐bound Al2O3‐Al composite under a nitrogen atmosphere, more stabilized MgAlON was formed.

Effect of MgO on corrosion mechanism under LF refining slag for MgAlON–MgO composites synthesized from spent MgO–C brick: Wetting behaviour, reaction process and infiltration mechanism

The Ladle Furnace (LF) refining slag resistance of MgAlON–MgO composites synthesized from spent MgO–C brick was investigated using the sessile drop technique, manifesting that MgAlON with slag corrosion thickness of 780 µm exhibits the best slag resistance than other composites. MgAlON–MgO composites react with the slag to generate calcium aluminate, spinel, and TiN. Furthermore, MgAlON–MgO composites with different MgO content show different corrosion process. The corrosion process of MgAlON and MgAlON–4.2 wt%MgO proceeds with wetting, reaction, and infiltration processes, while that of MgAlON–10.5 wt%MgO and MgAlON–15.7 wt%MgO only proceeds with wetting and infiltration processes. Compared with MgAlON–10.5 wt%MgO and MgAlON–15.7 wt%MgO, MgAlON and MgAlON–4.2 wt%MgO show low contact angle, presenting good slag wettability. Nevertheless, the viscosity of molten slag decreases with increasing MgO content, and MgAlON–MgO composites with high MgO content (MgAlON–10.5 wt%MgO and MgAlON–15.7 wt%MgO) show high porosity, thus aggravating the infiltration of molten slag. Compared with the wetting behaviour between molten slag and MgAlON–MgO composites, the infiltration of slag plays a decisive role in the slag corrosion process. Therefore, MgAlON and MgAlON–4.2 wt%MgO exhibit better slag resistance, showing the potential application in the ladle furnace.

Effect of MgO on wetting and corrosion behaviour of corundum substrate by CaO–SiO2–MgO (–Al2O3) slags

ABSTRACT Effect of MgO content on wetting and corrosion behaviour of corundum substrate by CaO–SiO2–MgO (−15%Al2O3) molten slags was investigated at 1450°C via joint application of a sessile drop technique, SEM–EDS detection and FactSage thermodynamic software. All slags exhibit good wettability on the substrate, and the contact angle values are small. Increasing MgO content from 7% to 9% in CaO-SiO2-MgO slags can increase the contact angle between the droplet and the substrate, while the substrate dissolution thickness and the slag penetration depth tend to decrease. Increasing MgO content from 8% to 15% in CaO-SiO2-MgO-15% Al2O3 slags can also increase the contact angle, but significantly decrease the slag penetration depth. The indirect dissolution thickness increases instead due to the formation of a large amount of MgAl2O4 by the interface reaction. The wettability can give an indication of the slag penetration depth in the substrate but not the dissolution thickness of the substrate.