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Vanadium slag contains several critical elements like V, Ti, Cr, Fe and Mn. In our previous work, V and Cr have been enriched by selective chlorination, increasing from 10.05% to 14.95% and 5.84%–8.69% separately. V and Cr still maintain the trivalence state in molten salt. In the current work, the electrodeposition behaviors of V3+ and Cr3+ in NaCl–KCl molten salt at 800 °C were investigated using cyclic voltammetry (CV) and square wave voltammetry (SWV) with a tungsten electrode. It was found that the reduction processes of V3+ and Cr3+ consist of two steps, M3+/M2+, M2+/M. The diffusion coefficients of V3+ and Cr3+ in NaCl–KCl molten salt were measured by CV. The effect of VCl 3 /CrCl 3 mass ratio on VCr alloy was investigated by a two-electrode under constant voltage. Pure Cr can be obtained at 2.8 V in the NaCl–KCl molten salt, while VCr alloy (3.71 mass % V-94.28 mass% Cr-2.01 mass % O) was obtained when electrolysis voltage was controlled to 2.8 V at 800 °C. The composition of VCr alloy can be designed by changing the molten salt composition. This method can be applied for direct preparation of VCr alloy from vanadium slag, thus offering the use of low cost raw materials with direct environmental benefits. • The main composition of chlorinated vanadium slag were the VCl 3 and CrCl 3. • The electrochemical behaviors of V3+ and Cr3+ in molten salt were investigated. • The diffusion coefficients of V3+ in NaCl–KCl molten salt were 8.72✕10−5 cm2s−1. • The diffusion coefficients of Cr3+ in NaCl–KCl molten salt were 26.5✕10−5 cm2s−1. • Alloys with different ratios of V to Cr were prepared. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen desorption from zirconium hydride with hydrogen content of 1.95 H/Zr in He and He–5%O2 atmospheres was studied by thermal desorption spectroscopy (TDS). The morphology, structure and valence states of the oxide layer formed on the surface of zirconium hydride were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that hydrogen desorption is retarded in the presence of oxygen. Heating in He leads to a large desorption range starting at 500°C while heating in He–5%O2 atmosphere delays decomposition to relatively higher temperature of 525°C. A protective oxide layer composed of monoclinic ZrO2 and small amount of tetragonal ZrO1.88, which acts as a very effective diffusion barrier. The O–H bond was observed in the oxide layer, which is beneficial to fix hydrogen atoms and prevent hydrogen diffusion. [Copyright &y& Elsevier]

• XPS method proved that Mn and S exist as positive divalent(Mn2+) and negative divalent(S2-), respectively at the gas-slag interface. • Comparing XPS and Raman, the structure of the CaO-SiO 2 -MnO slag has a gradient change trend from the interface to the body due to uneven distributions of elements. • Mn and S have a strong correlation, which is due to the existence of Mn cluster and the uneven distribution of charges. In this work, the interfacial element distribution and structure of CaO-SiO 2 -10%mass MnO slag was explored using the gas-slag equilibrium experimental method and XPS detection method at the temperature of 1873 K. Based on the full spectrum, the relative content of sulfur gradually decreases, the manganese has the same trend, while the calcium content keeps increasing. According to the analysis of the Mn2p and S2p spectra, it indicated that Mn and S exist as positive divalent (Mn2+) and negative divalent (S2-), respectively. The O1s fitting result indicates that the proportion of non-bridged oxygen (O-) increased, while that of bridged oxygen (O0) decreased with the etching time increased. The structural units obtained by Raman spectroscopy are closer to the evaluation data of the CaO-SiO 2 system, while the interfacial structure information tends to the MnO-SiO 2 system. Although CaS is thermodynamically more stable than MnS, the reason for the sulfur accumulation in the gas-slag interface is due to the d electron supplement from Mn. Thus, the concept of interface sulfide capacity is proposed. As the etching depth increases, the interface sulfide capacity decreases continuously. Comparing XPS and Raman, the structure has a gradient change trend at the gas-slag interface, which confirms the presence of the boundary layer at the gas-slag interface. [ABSTRACT FROM AUTHOR]

Co 3 O 4 modification is introduced to improve the Na-storage characteristic of P2–Na 2/3 Mn 0.75 Co 0.25 O 2 through a solid-state reaction. The synergistic effects of Co 3 O 4 modification and Co ions doping have significantly promoted sodium storage characteristics, in particular, cyclability at high-rate of the pristine oxide. The pseudo-capacitance effects of Co 3 O 4 modified layer can also offer electrochemical contributions to the pristine oxide. 2 wt% Co 3 O 4 modified cathode achieves 164.1 mAh g−1 at 0.1 C with the capacity retention of 85.6% at 100th cycle, 111.4 mAh g−1 at 1 C with the retention of 72.3% at 400th cycle, 85.7 mAh g−1 at 5 C with the retention rate of 73.5% at 1000th cycle, and 68.6 mAh g−1 at 10 C with 82.0% capacity retention after 1000 cycles. Especially, 2 wt% Co 3 O 4 modified cathode can reach up to the capacity retention of 90.1% at 1 C at 120 cycles, 90.4% at 5 C after 350 cycles and 90.7% at 10 C over 640 cycles. The high-rate cycling performance of the modified cathode is also involved in its high reversible P2–P3 transition during Na+ insertion/extraction. Therefore, the excellent Co 3 O 4 modified cathode will provide impetus for future developments and applications of sodium-ion batteries. Image 1 • Co 3 O 4 modified layer can provide pseudo-capacitance contributions to the pristine. • Co ions have doped into the Mn-sites in T M –O 2 slabs of the pristine lattice. • Structure stability is significantly enhanced by the synergism of modification and doping. • The modified cathode achieves the excellent cyclability at high-rate. • Ex-situ XRD patterns reveal the phase transition its high reversible P2–P3 transition. [ABSTRACT FROM AUTHOR]

The influence of Ce addition on the precipitation of ferrite (δ) and sigma (σ) phase in super-austenitic stainless steels during solidification was investigated via a combined experimental and theoretical approach. Thermodynamic calculations reveal that the secondary phase of δ and σ are precipitated in sequence near the end of the solidification process due to the segregation of Mo and Cr. The Ce addition improves the thermal stability of the δ, expands the range of Mo content for δ phase precipitation and increases the δ fraction in the solidified structure in the Gulliver–Scheil model. Experimental observation shows that a small addition of Ce accelerates δ nucleation in the interdendritic solute-rich liquid, refines the solidified structure and reduces Mo and Cr segregation, which suppresses precipitation of the σ phase. The σ phase precipitation is replaced by δ phase precipitation after a Ce addition of 0.016%. The change in the secondary phase from σ to δ shortens the time required for homogenization and reduces the nano-hardness of the interdendritic secondary phase, which is significant for hot working. • The mainly secondary phase in S31254 solidified structure is intermetallic sigma. • Ce addition in S31254 could improve the thermal stability of ferrite (δ) during solidification. • Ce addition could promote δ nucleation in interdendritic, refine the solidified structure and reduce Mo segregation. • Ce addition in S31254 could change the secondary phase from sigma to ferrite in solidified structure. • The secondary phase transition is significant for hot working. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOFs) have demonstrated excellent properties for application in energy storage field. In this work, we use a facile and solvent-free method to fabricate ZIF-67 films on foam Ni, Cu, Fe and Zn substrates. The pre-electrodeposited films are exposed to 2-methylimidazole vapor to generate ZIF-67 films. The morphology of the ZIF-67 films depends on the substrates and reaction duration. Specially, a hollow and opened polyhedron appearance is generated on the foam Ni substrate, which presents a uniform and smooth distribution. All ZIF-67 films on different substrates demonstrate good electrochemical performances when they are utilized as the active materials in the supercapacitors. The ZIF-67 film on the foam Ni substrate has 105 mF/cm2 areal specific capacitance at 10 mA/cm2 current density, showing superior electrochemical properties than that on other substrates. The specific energy can reach 24.5 μWh/cm2 at a high specific power of 14 mW/cm2 in an asymmetric supercapacitor, with Ni@Z67 as the cathode material and active carbon as anode electrode material. The process combining a simple electrodeposition method with solvent-free CVD transformation will be useful for the fabrication of MOFs films and their potential applications in various fields. [Display omitted] • ZIF-67 films on foam Ni, Cu, Fe and Zn were successfully prepared using solvent-free MOF-CVD method. • The morphology evolution of the ZIF-67 films has been investigated and the ZIF-67 film on Ni substrate presents a unique hollow and opened polyhedron morphology. • The ZIF-67 film on foam Ni has superior electrochemical performances as active material for supercapacitors. [ABSTRACT FROM AUTHOR]

• AIMD method is used to calculate structure and charge information of the liquid slag. • The stable state and environmental information of sulfur in liquid silicate is obtained. • The desulfurization mechanism of the two systems was elucidated based on charge analysis. [Display omitted] In present study, systematic investigations of the CaO-SiO 2 and MnO-SiO 2 slag were performed of the evolution of the structure, and the sulfur dissolution mechanism at a temperature of 2000 K using ab initio molecular dynamics simulations. The results show that the structure and charge of CaO-SiO 2 and MnO-SiO 2 are very different. Firstly, Si-O has a strong polar bond while Ca-O and Mn-O show ionicity, and Mn-O has weaker ionicity than Ca-O. A small amount of Mn-Mn clusters are found in liquid MnO-SiO 2. Secondly, charge distribution depicts that there is less charge around Ca, while there are relatively more charges around Mn. Bader charge analysis indicates that Mn and O have a broad valence distribution in MnO-SiO 2 compared with CaO-SiO 2. Thirdly, Sulfur prefers to form stable bonds with Mn atoms (Mn-S-Mn), whereas Si-S bonds are unstable and cannot be found in S-doped MnO-SiO 2 silicate. However, in the CaO-SiO 2 system, the S atom does not undergo rapid bond transitions. The study of the desulfurization mechanism shows that the uneven distribution of charge in MnO-SiO 2 system will affect the transformation of oxygen types, resulting in the decrease of bridged oxygen and the increase of non-bridged oxygen. However, there is no charge effect in CaO-SiO 2 system, and the non-bridged oxygen will be consumed in the desulfurization process, resulting in the decrease of non-bridged oxygen and the increase of bridged oxygen. This mechanism well explains the experimental results from a more microscopic perspective, which is of great significance to the research on the removal mechanism of S in the metallurgical industry. [ABSTRACT FROM AUTHOR]

The crack-free bulk hydrides of Zr Y alloys have been prepared and characterized by X-ray diffraction, optical microscopy and electron probe microanalysis to study the phase structure, microstructure and composition distribution, respectively. It was found that the as-received hydrides were composed of zirconium hydrides and yttrium hydrides mixtures. We performed thermogravimetry and simultaneous thermal desorption spectroscopy (TG/TDS) under Ar and CO 2 atmosphere to study the effect of yttrium and surface oxide layer on hydrogen desorption from zirconium hydride. The results showed that zirconium hydrides containing higher Y content tend to have higher hydrogen desorption temperatures and higher hydrogen content, suggesting that hydrogen could be retained in the hydride matrix by alloying with yttrium. X-ray diffraction indicated that an oxide layer was formed on the surface of the metal hydrides under CO 2 atmosphere, and yttrium could stabilize t-ZrO 2 phase in the oxide layer, thus inhibiting hydrogen desorption from the metal hydrides at the reactor working temperature. [ABSTRACT FROM AUTHOR]

Aiming at the deficiencies of the three typical "external gettering" systems: metal-oxide equilibrium deoxidation (MED), halide flux deoxidation (HFD) and electrochemical deoxidation (ECD), a novel deoxidation method based on the combination of oxytropic rare earth metal Y and Ca for in-depth deoxidation of Zr-O solid solution was proposed. The thermodynamic properties of the deoxidation method were analyzed, and it was found that the addition of metallic Y could significantly improve the deoxidation ability of the Ca-CaCl 2 system, because Y could form Y-Y 2 O 3 equilibrium to "anchor" the activity of CaO (a CaO) at a very low level. When the activity of Y 2 O 3 (a Y2O3) and a CaO in the flux conforms to a Y2O3 < 18.9 a 3 CaO at 1173 K, the deoxidation mode is thermodynamically feasible. Experiments were conducted to verify the method. The results showed that even if CaO was saturated in CaCl 2 flux, the oxygen content of Zr-O solid solution could still be controlled at the level of less than 100 ppm, thus the "anchoring effect" of Y on a CaO was verified. The oxygen content, phase and microstructure of the reacted Y specimens were analyzed, which suggested that when the ratio of CaO was less than 40 % of its solubility in CaCl 2 flux, the oxygen potential of the system was controlled by Y-O solid solution, and when it was greater than 40 %, the oxygen potential of the system was controlled by Y-Y 2 O 3 equilibrium. [Display omitted] • A novel in-depth deoxidationmethod based on the combination of oxytropic metals Y and Ca was proposed. • The formation of Y-O solid solution and Y-Y 2 O 3 equilibrium can "anchor" a CaO at an extremely low level. • The oxygen content of zirconium can be stably reduced to less than 100 ppm using this deoxidation model. [ABSTRACT FROM AUTHOR]

The correlation between structural stability and mechanical properties of Pt–Zr alloys is systematically investigated by first-principles calculations. Additionally, the thermodynamic properties and electronic structure are discussed in detail. The convex hull indicates that the Pt 10 Zr 7 with orthorhombic structure is more stable than other Pt–Zr alloys at ground state. The bulk modulus of Pt–Zr alloys increases linearly as Pt concentration increases. Pt 8 Zr has strong volume deformation resistance, which is derived from the high Pt concentration. Pt 3 Zr exhibits strong shear deformation resistance and has high elastic stiffness, which originated from the strong Pt–Pt metallic bond along the b- direction. The trend of Debye temperature is consistent with the variation of shear modulus and Young’s modulus, and the calculated Debye temperature of Pt 3 Zr is 342 K, which is bigger than other Pt–Zr alloys. The results provide a helpful for the design of Pt-based high-temperature structural materials with excellent mechanical properties. [ABSTRACT FROM AUTHOR]

A Ti–Al intermetallic compound coating was fabricated on Ti–6Al–4V alloy by combined ultrasonic impact treatment and electrospark deposition. The principle of the combined process is described in detail based on studies of the chemical states, microstructure, phase compositions, microhardness, and surface residual stress of the coating. Many new Ti–Al intermetallic compounds distinct from the deposition materials are found to make up the coating, along with a small amount of Al 2 O 3 . The high energy of the electrospark facilitates the chemical reactions among elements. Further, the impact process produces a plastic deformation layer. The microhardness of the Ti–6Al–4V under the coating also increased because of the plastic deformation layer. Finally, the surface residual stress of samples treated by the combined process is compressive stress. [ABSTRACT FROM AUTHOR]

The phase diagrams and thermodynamic basis for the Bi–Se and Zn–Se binary systems are analyzed in this work, where the CALPHAD technique is adopted and the associated solution model is applied for the liquid phase. Two binary associates, Bi 2 Se 3 and ZnSe, are assumed to be present in Bi–Se and Zn–Se melts respectively. Bi 3 Se 2 , Bi 2 Se 3 and ZnSe are treated as stoichiometric phases, while BiSe is described with the two-sublattice model in order to respect its large solubility. The Gibbs free energies of each phase are formulated in this work, which allow liquidus, enthalpies of mixing, activities, and enthalpies of formation and entropies of formation to be well represented, the results of which can provide fundamental information for semiconductor design. [ABSTRACT FROM AUTHOR]

Highlights: [•] The associated solution model is adopted for the liquid phase. [•] Comprehensive comparisons between the calculated and experimentally measured data. [•] Important to study thermodynamic behaviors of impurity in Te-containing materials. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of zirconium-oxygen (Zr–O) solid solution and its deoxidation by calcium in CaCl 2 molten salt were studied using a chemical equilibration technique. In the temperature range from 1173 to 1373 K, the equilibrium oxygen contents in Zr were measured experimentally under coexistence of Ca and CaO in CaCl 2 molten salt. The oxygen content in Zr was reduced from about 800 ppm to a minimum of less than 100 ppm. Then a CaO sensor — niobium-oxygen (Nb–O) solid solution was employed to equilibrate with Zr–O solid solution to determine the oxygen activity coefficient in Zr–O solid solution. Zr and Nb specimens were submerged in Ca-saturated CaCl 2 molten salt containing different amounts of CaO. CaCl 2 melt was used for a homogeneous reaction and composition. The experimental results shown that Henry's law held and the activity coefficient of oxygen was constant within the concentration range of this study. Based on the result, the standard formation Gibbs free energy of Zr–O solid solution was obtained as a function of temperature: 1/2O 2 (g) = O (in Zr) Δ G Z r − O θ = − 543577 + 64. 3 T (1173−1373K) The p-t-x relationship of the deoxidation system was obtained simultaneously, which make the deoxidation limit and variation trend of oxygen content in Zr–O solid solution predictable and controllable under different conditions. Oxygen distribution coefficient between Zr–O solid solution and Nb–O solid solution was found in agreement with the theoretical value and independent of oxygen potential of the system. • A simple method is used to verify the validity of Henry's law in Zr–O solution. • The formation Gibbs energy of Zr–O solid solution was obtained. • The p - t - x relationship of the deoxidation system was also established. • Oxygen distribution coefficient is independent with external oxygen potential. • The results of this paper can make the deoxidation process of Zr predictable. [ABSTRACT FROM AUTHOR]