Search

As a promising anode material for magnesium ion rechargeable batteries, magnesium metavanadate (MgV2O6) has attracted considerable research interest in recent years. A MgV2O6 sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V2O5 powder under an air atmosphere. The solid-state phase transition from α-MgV2O6 to β-MgV2O6 occurred at 841 K and the enthalpy change was 4.37 ± 0.04 kJ/mol. The endothermic effect at 1014 K and the enthalpy change was 26.54 ± 0.26 kJ/mol, which is related to the incongruent melting of β-MgV2O6. In situ XRD was performed to investigate phase transition of the as-prepared MgV2O6 at high temperatures. The cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group, and the lattice parameters of a = 9.280 Å, b = 3.501 Å, c = 6.731 Å, β = 111.76°. The solid-state phase transition from α-MgV2O6 to β-MgV2O6 was further studied by thermal kinetics, indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating rate. Additionally, the enthalpy change of MgV2O6 at high temperatures was measured utilizing the drop calorimetry, heat capacity was calculated and given as: Cp = 208.3 + 0.03583T-4809000T−2 (298 – 923 K) (J mol−1 K−1), the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV2O6 at high temperatures.

The abundant metal Ti is a high-quality metal with lightweight, high strength, and corrosion resistance. However, due to its harsh preparation conditions, the price remains high, so titanium metal's simple and effective products have become a challenge for the world's scientific research community. In this paper, by calculating the oxygen potential of Ti–O, Ti–H, and Ti–H–O solid solutions, the oxygen potential of Ti–H–O was obtained when the oxygen content was 0.03 and 0.009. As H2 enters the Ti–O lattice, the oxygen potential of the Ti–H–O system increases with the increase of H content. Thermodynamic calculations showed that introducing hydrogen effectively destroyed the stability of Ti–O solid solutions. At the same time, this paper uses a magnesiothermic as a reducing agent. To verify the feasibility of the above thermodynamics, reduce the spent V2O5–WO3/TiO2 catalyst (Ti > 80 wt%) of titanium-rich materials in a hydrogen atmosphere. Finally, the spent V2O5–WO3/TiO2 catalyst was reduced at 750 °C for 8–24 h to obtain TiH2 powder with an oxygen content of 0.9 wt%.

The environmentally assisted stress corrosion cracking (SCC) behaviours of low alloy E690 steel in SO2-containing NaCl solution are investigated. The result shows that the corrosion on the metal surface becomes serious with the addition of NaHSO3, which mainly exhibits pitting corrosion. When the NaHSO3 concentration increases to 0.01 mol/L, the static load enhances the local AD resulting in the pits, and the stress concentrations around the pits leads to the initiation and propagation of the crack. And the SCC exhibits the transgranular cracking controlled by a combined mechanism of anodic dissolution (AD) and hydrogen embrittlement (HE). With the addition of NaHSO3, the corrosion potential on the surface of metal changes the crack growth rate through altering the pH and electrochemistry at the crack tip. Compared to the static load, the dynamic load promotes the dislocation accumulation, increases the electrochemical activity at the crack tip, which facilitates the HE and further accelerates the crack growth.

Due to TiAl alloys’ excellent properties, TiAl alloys have received widespread attention from researchers. However, the high energy consumption and lengthy process of traditional preparation methods have always limited the large-scale application of TiAl alloys. This article develops a new method for preparing TiAl-based alloy powder via the magnesium thermal reduction of TiO2 in AlCl3-KCl molten salt. In this study, the proportion of AlCl3&KCl molten salts was determined. We conducted phase analysis on the final product by studying the changes in temperature and time. It was found that the TiAl3 alloy powder could be obtained by being kept at 750 °C for 2 h, with an oxygen content of 3.91 wt%. The reaction process for the entire experiment was determined through thermodynamic calculations and experimental analysis, and the principles of the reduction process are discussed.

The dehydration of titanium dioxide, which is the carrier for denitration catalysts, is a crucial control step in the preparation of functional materials and has an impact on the performance of the product. In this study, the kinetics of the dehydration behavior and reaction mechanism of titanium dioxide were investigated under different atmospheres by measuring the thermal analysis curve of titanium dioxide at different heating rates. The results indicate that the dehydration behavior of the catalyst carrier titanium dioxide is closely related to the calcination atmosphere. The dehydration rate differed for oxygen and no-oxygen atmospheres. Dehydration began quickly in an oxygenated atmosphere and then slowed down towards the end of the reaction, completing slowly in an oxygen-free atmosphere. Kinetic calculations were carried out using modeless and mode function methods. The results show that dehydration of titanium dioxide is consistent with the Avrami–Erofeev equation in an oxygen-containing atmosphere and with the power function rule in an oxygen-free atmosphere, with the process of dehydration being influenced by the formation and growth of crystal nuclei.

PurposeOsteoporosis is a complex bone disease influenced by numerous factors. Previous studies have found that some metabolites are related to bone mineral density (BMD). However, the associations between metabolites and BMD under the influence of genes and lifestyle have not been fully investigated.MethodsWe analyzed the effect of metabolites on BMD under the synergistic effect of genes and lifestyle, using the data of 797 participants aged 55–65 years from the Taizhou Imaging Study. The cumulative sum method was used to calculate the polygenic risk score of SNPs, and the healthful plant-based diet index was used to summarize food intake. The effect of metabolites on BMD changes under the influence of genes and lifestyle was analyzed through interaction analysis and mediation analysis.ResultsNineteen metabolites were found significantly different in the osteoporosis, osteopenia, and normal BMD groups. We found two high-density lipoprotein (HDL) subfractions were positively associated with osteopenia, and six very-low-density lipoprotein subfractions were negatively associated with osteopenia or osteoporosis, after adjusting for lifestyles and genetic factors. Tea drinking habits, alcohol consumption, smoking, and polygenic risk score changed BMD by affecting metabolites.ConclusionWith the increased level of HDL subfractions, the risk of bone loss in the population will increase; the risk of bone loss decreases with the increased level of very-low-density lipoprotein subfractions. Genetic factors and lifestyles can modify the effects of metabolites on BMD. Our results show evidence for the precise prevention of osteoporosis.

Stability diagrams are of great importance for investigating deoxidation equilibrium and controlling inclusions in molten steel. Combined with programming for calculation and drawing, the three-dimensional stability diagrams of MgO, MgO·Al2O3, and Al2O3 in the Fe–Al–Mg–O system were successfully drawn, which can visually explain the meaning of the iso-oxygen contours and the borderlines among different phases. They also offer straight evidence that the borderline method is imperfect. The three-dimensional stability diagrams can visually show more vital details that cannot be illustrated by the iso-oxygen contours. The most significant advantage of three-dimensional stability diagrams is not only judging the most stable phase in the specific component area but also visually showing the transformation trend among the phases from a three-dimensional perspective, especially when the equilibrium surfaces of these phases are relatively close. Besides, an interesting transformation of inclusions in the Fe–Al–Mg–O system was found. When the magnesium content is higher than 0.0065% and the aluminum content is lower than 0.21%, the equilibrium products of aluminum-magnesium composite deoxidation may be transformed from MgO to MgO·Al2O3 and Al2O3 in turn, which can be directly observed from the three-dimensional stability diagram based on the calculations.

The viscous flow of CaO–SiO2–Al2O3–MgO–TiO2–Cr2O3 slag (CaO/SiO2 = 1.1, Cr2O3 = 0.5 mass%) were investigated to promote understanding of the effect of TiO2 addition on the viscous behavior of chromium-containing vanadium-titanium blast furnace slag. The viscosity of the slag was measured using a rotating crucible viscometer. Raman spectroscopy analysis was performed to correlate the viscosity to slag structure. The viscosity of slag was found to significantly decrease with increasing TiO2 content at a fixed basicity. It is because the Ti4+ continuously detached from the network structure, the content of [Ti2O6]4- decreased, and the content of [TiO4]4- tetrahedral monomer increased, which made the slag structure simplified. Consequently, the polymerization degree of the slag decreases with increasing TiO2 content. The variation in slag structure is consistent with the change in measured viscosity.

The present study monitored the foaming phenomenon originating from the reaction of titanium-bearing blast furnace slag by using the relationship between the current change in a circuit and the foaming height. A series of experiments at room temperature and high temperature were designed to check the feasibility and reproducibility of the experimental apparatus. Experiments at different levels of basicity and TiO2 content at high temperature were designed to determine the effect of these parameters on the relationship between the foaming height and current. It was proved that the electric current method used in this study to monitor the real-time foaming process is feasible and reliable. The relationship between the foaming height and current change was also established.

For several years, ordinary vanadium-titanium magnetite has been rapidly consumed because of its use in smelting. Thus, sources of chromium-containing vanadium-titanium magnetite will need to be developed and utilized in the future. Therefore, the physical and chemical properties of the blast furnace slag that results from smelting chromium-containing vanadium-titanium magnetite should be completely understood. In the present work, the viscous flow characteristics of CaO–SiO2–MgO–TiO2–Al2O3–Cr2O3 system slag were investigated both theoretically and experimentally to promote a better understanding of the effect of Cr2O3 addition on the viscous behavior of slag. With increasing Cr2O3 content, the viscosity first decreases and then increases. When the Cr2O3 content is a maximum of 0.5 wt.%, Cr2O3 serves as a network modifier to simplify the slag structure and reduce the viscosity. When the added amount was a minimum of 1.5 wt.%, perovskite and spinel phases were formed in the slag, resulting in increased viscosity.

The extracted titanium tailings slag (TS) is a by-product of titanium extraction from the blast furnace slag. Its chemical composition is similar to that of ground granulated blast furnace slag (GGBS), but the relatively lower reactivity limited its utilization as a supplementary cementitious material. In this study, the reactivity of TS was improved by mechanical grinding, and the optimum property of finely ground TS was selected to replace fly ash (FA) in the alkali-activated FA-GGBS binder. The influence of TS content on the fluidity, setting time, and compressive strength of the ternary binder was investigated. X-Ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy were used to analyze the effect of TS on the reaction process. Results showed that the optimum reactivity index of TS was 81.18% at 28 days when it was ground for 15 min in a ball mill. The highest compressive strength of the alkali-activated ternary binder was achieved when the replacement of FA by ground TS was 40%, and its 28-day compressive strength was 49.3 MPa, approximately 22% higher than the binder without TS. The addition of the TS would accelerate the reaction process of binder to form more products, including C-(A)-S-H and gismondine.

Direct reduction–magnetic separation followed by low temperature chlorination was a promising process to comprehensively utilize vanadium–bearing titanomagnetite (VTM). Herein, the conversion of titanium oxides to TiC/TiN/Ti(C,N) is extremely critical. In this study, the carbonization and nitridation of VTM during carbothermal reduction under different atmosphere was investigated. Thermodynamic analysis indicated that the reduction, carbonization and nitridation of VTM was feasible via carbothermal reduction by carbon. Introducing N2 into the reaction system was beneficial to decrease the equilibrium temperature by forming TiN instead of TiC. The experimental results showed that the Fe metallization ratio (MFe/TFe) reached about 100 wt% above 1150 °C regardless of the reduction atmosphere. The maximum carbonization ratio of Ti (TiC/TTi) was 98.55 wt% after roasting at 1300 °C for 2.5 h in Ar atmosphere. The total carbonization and nitridation ratio (TiN/TTi) was 99.55 wt% when reduced at 1300 °C for 2.5 h in N2 atmosphere. The main Ti–bearing phases were reduced and carbonized in the order of ilmenite (FeTiO3)→ ferropseudobrookite (FeTi2O5)→ Fe,Ti,Mg Oxide (Fe0.33Ti0.46Mg0.21)(Ti1.9Mg0.1)O5→ titanium carbide (TiC). TiC was further nitrided to form TiN, which combined with TiC as titanium carbonitride (Ti(C,N)). TiC/TiN/Ti(C,N) granules, with a particle size less than 10 μm, were mainly dispersedly distributed in metallic iron. They also gathered at the edge of metallic iron and part of them existed in the the interval between metallic iron and gangue minerals.

Abstract Ti matrix composites reinforced with 1–5 wt% graphene oxide (GO) were prepared by hot-pressed sintering in argon atmosphere. The effect of sintering temperature on the microstructures and mechanical properties of the composite was also evaluated. The results show that TiC nanoparticles were formed in situ as interfacial products via the reaction between Ti and GO during sintering. With increases in GO content and sintering temperature, the amount of TiC increased, improving the mechanical properties of the composites. GO was also partly retained with a lamellar structure after sintering. The composite reinforced with 5 wt% GO exhibited a hardness of 457 HV, 48.4% higher than that of pure Ti at 1473 K. The Ti-2.5 wt% GO composite sintered at 1473 K achieved a maximum yield stress of 1294 MPa, which was 62.7 % higher than that of pure Ti. Further increasing the GO content to 5 wt% led to a slight decrease in yield stress owing to GO agglomeration. The fracture morphology of the composite reinforced with GO exhibited a quasi-cleavage fracture, whereas that of the pure Ti matrix showed a ductile fracture. The main strengthening mechanism included grain refinement, solution strengthening, and dispersion strengthening of TiC and GO.

Titanium matrix composites reinforced by graphene oxide (GO) and carbon nanotube (CNT) were successfully prepared by hot-pressing sintering. The effect of GO content on dispersion and particle size of CNT was analysed. In addition, the microstructure, phase structure and mechanical properties of Ti/GO-CNT composites were characterized, and the synergistic strengthening mechanism was investigated. The results show that dispersion of CNT can be significantly improved by adding GO. TiC particles with size of 100–200 nm are formed in situ between matrix and reinforcements. CNT and GO still partly keep an integrated structure after sintering. A significant synergetic effect was observed between GO and CNT that improved the mechanical properties of the composite. The maximum hardness and yield strength of the composite were 771.5 HV and 1387.1 MPa, which is 150% and 74% higher than that of pure Ti when the GO/CNT ratio is 5:1. The synergistic strength enhancement reaches a maximum when GO/CNT ratio is 1:1.

The Special Issue on “Metallurgical Slag” is a collection of 23 original articles dedicated to theoretical and experimental research works providing new insights and practical findings in the field of metallurgical slag-related topics [...]

The steel micro-alloyed with ferrovanadium nitride has extremely superior properties that make it widely utilized in structural components, construction and aircraft. The conventional methods for synthesizing ferrovanadium nitride include nitridation of pure ferrovanadium alloy or carbothermal nitridation of metallic oxides, using nitrogen or ammonia gas as nitrogen sources. In this study, ferrovanadium nitride (FeV45N) was prepared by direct reduction and nitridation of the corresponding metal oxides with ammonia as the reductant and nitrogen source. This method avoids the introduction of other impurity elements, except the negligible trace elements accompanied with the raw materials. The thermodynamics of the reduction and nitridation process were initially analyzed. During the subsequent ammonia reduction process, the FeV45N powders were successfully obtained at 1273 K for 6 h. The obtained powders were pressed into cylindrical briquettes by hot pressing (HP) at 1473 K for 1 h in vacuum. In the investigation, the X-ray diffraction and morphological analysis of the products was also carried out, and the reaction mechanisms were discussed in detail. The nitrogen content of the final product can reach 11.85 wt. %, and the residual oxygen content can be reduced to 0.25 wt. %. By sintering, the density of the alloy can reach 5.92 g/cm3.

In this paper, the effect of titanium carbonitride (Ti(C,N)) on the viscosity of high-titanium-type blast furnace slags was investigated. The different Ti(C,N) contents were achieved by adjusting the reduction degree of TiO2 to reflect the real characteristics of the high-titanium slag. The results show that the viscosity of the slag increased with the increasing Ti(C,N) content and decreased with the rising temperature. A deviation between the measured and the fitted viscosity appeared as the content of the Ti(C,N) was beyond 4 wt%. Furthermore, the apparent viscous flow activation energy of the slag ranged from 106.13 kJ/mol to 235.46 kJ/mol by varying the Ti(C,N) contents from 0 wt% to 4.97 wt%, which was evidently different from the results of previous studies. The optical microscope and energy dispersive X-ray spectroscopy (EDS) analysis show that numerous bubble cavities were embedded in the slags and the Ti(C,N) particles agglomerated in the solidified samples. This phenomenon further indicates that the high-titanium slag is a polyphase dispersion system, which consists of liquid slag, solid Ti(C,N) particles and bubbles.

Understanding the Si segregation behavior in hypereutectic Al-Si alloys is important for controlling the micro- and macrostructures of ingots. The macrosegregation mechanism and morphological evolution of the primary Si phase were investigated during electromagnetic directional solidification (EMDS). Both numerical simulations and experimental results strongly suggested that the severe macrosegregation of the primary Si phase was caused by fluid flow and temperature distribution. Microscopic analysis showed that the morphological evolution of the Si crystal occurred as follows: planar → cellular → columnar → dendritic stages during EMDS. Based on constitutional supercooling theory, a predominance area diagram of Si morphology was established, indicating that the morphology could be precisely controlled by adjusting the values of temperature gradient (G), crystal growth rate (R), and solute concentration (C0). The results provide novel insight into controlling the morphologies of primary Si phases in hypereutectic Al-Si alloys and, simultaneously, strengthen our understanding of the macrosegregation mechanism in metallic alloys.

Background/Aim: Human dental pulp mesenchymal stem cells (hDPSCs) are considered to be a good cell source for cell-based clinical therapy, due to the advantages of high proliferation capacity, multilineage differentiation potential, immune regulation abilities, less ethnic concerns and noninvasive access. However, hDPSCs were traditionally isolated and expanded in medium containing fetal bovine serum (FBS), which is a barrier for clinical application due to the safety issues (virus transmission and allergy). Although many studies make efforts to screen out a suitable culture medium, the results are not promising so far. Therefore, a standard good manufacturing practice (GMP) compliant culture system is urgently required for the large-scale cell production. This study aimed to find suitable culture conditions for producing clinical grade hDPSCs to meet the requirements for clinical cell-based therapy and further to promote the application of hDPSCs into tissue regeneration or disease cure. Materials and Methods: We derived hDPSCs from nine orthodontic teeth expanded in two different media: a GMP compliant and xenogeneic serumfree medium (AMMS) and a serum containing medium (SCM). Cell propterties including morphology, proliferation, marker expression, differentiation, stemness, senescence and cytokine secretion between these two media were systematically compared. Results: hDPSCs cultured in both media exhibited the typical characteristics of mesenchymal stem cells (MSCs). However, we found that more cell colonies formed in the primary culture in AMMS, and the hDPSCs displayed higher proliferation capacity, differentiation potential and better stemness maintenance during sub-culturing in AMMS. Conclusion: Cell properties of hDPSCs could be improved when they were isolated and expanded in AMMS, which might provide a good candidate of culture medium for large-scale cell manufacturing. [ABSTRACT FROM AUTHOR]