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To enhance the durability of copper tuyeres in blast furnaces, it is necessary to apply coatings on their surfaces to protect against wear caused by high-temperature coke. In this study, a series of in-situ synthetic TiC-reinforced Stellite 6 alloy coatings containing a Ni60A interlayer were successfully produced on copper substrates using 5–45 wt% TiFe/Cr3C2 precursor powders. The coatings exhibited excellent metallurgical bonding with the Ni60A interlayer, and an elemental transition zone was formed at the interface between the coating and the interlayer. XRD Rietveld refinement analysis revealed that the T45 coating with 45 wt% of precursor powder showed the highest TiC phase content of 12.27 %, with an average hardness of 658.15 HV0.2, which was 31.2 % higher than that of the Stellite 6 alloy. The wear mechanism of the Stellite 6 coating was plastic delamination at 25 °C, and oxidative wear at 500 °C. As the TiC particle content in the coating increased, the dominant wear mechanism tended to shift towards abrasive wear. The specific wear mechanism of the coating was influenced by the content of coating phases and the operating temperature. The best wear resistance was achieved by the T45 coating, which showed an abrasive wear mechanism at both 25 °C and 500 °C, with a wear resistance of 4.47 and 5.94 times higher than that of the Stellite 6 alloy respectively.

The high reflectivity and excellent thermal conductivity exhibited by copper substrates pose considerable challenges for conventional laser cladding techniques aiming to achieve high-performance coatings on their surfaces. In this study, a novel blue diode laser cladding approach was proposed to prepare nickel-based coatings on copper substrates. Under the conditions of a preheating temperature of 200 °C and laser power of 1500 W, a Ni60A coating was successfully fabricated on the surface of pure copper, with metallurgical bonding achieved and no crack defects observed. The average microhardness of the coating ranges from 468 HV0.1 to 775 HV0.1, which is approximately 8.8–14.6 times greater than that of the copper substrate. Furthermore, the wear resistance of the coating is approximately 3.6–4.7 times higher than that of copper at 25 °C, and approximately 3.8–5.4 times higher at 300 °C. The performance of the coating exhibit gradient variations in the cladding direction. Consequently, the challenges posed by the high laser reflectivity and the need for a high preheating temperature of copper substrate have been effectively overcome through the utilization of a blue laser cladding, facilitating the industrial-scale preparation of large-area coatings on copper components.

Abstract Sodium ion batteries (SIBs) have attracted great interest as candidates in stationary energy storage systems relying on low cost, high abundance and outstanding electrochemical properties. The foremost challenge in advanced NIBs lies in developing high-performance and low-cost electrode materials. To accelerate the commercialization of sodium ion batteries, various types of materials are being developed to meet the increasing energy demand. O3-type layered oxide cathode materials show great potential for commercial applications due to their high reversible capacity, moderate operating voltage and easy synthesis, while allowing direct matching of the negative electrode to assemble a full battery. Here, representative progress for Ni/Fe/Mn based O3-type cathode materials have been summarized, and existing problems, challenges and solutions are presented. In addition, the effects of irreversible phase transitions, air stability, structural distortion and ion migration on electrochemical performance are systematically discussed. We hope to provide new design ideas or solutions to advance the commercialization of sodium ion batteries.

To clarify the influence of process parameters on the microstructure and wear resistance of coating, a series of Ni60 A alloy were deposited on copper surface by plasma cladding under different preheating temperatures. The obtained coatings were new alloy materials formed by the dilution of Ni60 A alloy with Cu, and their microstructure and properties were closely related to the dilution rate. With the increase of preheating temperature, the dilution rate of the coatings increased obviously, which led to a gradual increase of the copper content in the γ-(Cu, Fe, Ni) solid solution phase, thus resulting in compositional inhomogeneity and performance deterioration of the coating. From 500 °C to 800 °C (preheating temperature), the average hardness of the coating decreased from 680.3 HV0.1 to 406.6 HV0.1, and the wear resistance reduced by 2.8 times. The wear mechanism of the coating changed from abrasive wear to the combination of abrasive wear and adhesive wear. For practical applications, to ensure the excellent wear resistance of the coating, the preheating temperature should be controlled at a low level.

The practical application of sodium-ion batteries at subzero temperatures is hindered by the slow Na-ion transfer kinetics. Here, the authors reported the niobium doping of P2-type cathode active material capable of efficient battery cycling at low temperatures such as −40 °C.

The two-dimensional MAX phases with compositional diversity are promising functional materials for electrochemical energy storage. Herein, we report the facile preparation of the Cr2GeC MAX phase from oxides/C precursors by the molten salt electrolysis method at a moderate temperature of 700°C. The electrosynthesis mechanism has been systematically investigated, and the results show that the synthesis of the Cr2GeC MAX phase involves electro-separation and in situ alloying processes. The as-prepared Cr2GeC MAX phase with a typical layered structure shows the uniform morphology of nanoparticles. As a proof of concept, Cr2GeC nanoparticles are investigated as anode materials for lithium-ion batteries, which deliver a good capacity of 177.4 mAh g−1 at 0.2 C and excellent cycling performance. The lithium-storage mechanism of the Cr2GeC MAX phase has been discussed based on density functional theory (DFT) calculations. This study may provide important support and complement to the tailored electrosynthesis of MAX phases toward high-performance energy storage applications.

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science communities. Electrochemistry, considered a promising strategy, has been explored to produce silicon due to prominent advantages: (a) high electricity utilization efficiency; (b) low-cost silica as a raw material; and (c) tunable morphologies and structures, including films, nanowires, and nanotubes. This review begins with a summary of early research on the extraction of silicon by electrochemistry. Emphasis has been placed on the electro-deoxidation and dissolution–electrodeposition of silica in chloride molten salts since the 21st century, including the basic reaction mechanisms, the fabrication of photoactive Si films for solar cells, the design and production of nano-Si and various silicon components for energy conversion, as well as storage applications. Besides, the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are evaluated. On this basis, the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed, which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

The evolution of microstructure and wear resistance of Co-based alloy coating reinforced with WC phase prepared on copper substrate by plasma cladding were investigated. As the WC contents increased, several carbide phases appeared in the coating, the shape of these carbide phases grew from punctate and flower to block and dendrite. The proportion of these carbide phases such as M3W3C and M6W6C in the coating increased, which caused the average hardness to improve from 553.43 HV0.1 to 954.64 HV0.1. Compared with pure cobalt-based alloy coating, WC/cobalt-based coating had a higher oxidation degree and forms CoWO4 phase. The Co-based coating with 40% WC exhibited relatively good wear resistance at room temperature, 400 °C and 500 °C. At 600 °C, the sample with 10% WC possessed the lowest wear weight loss.

Microstructure evolution of the joints formed by Ag-6.6 mol% Cu brazing BaCo0.7Fe0.2Nb0.1O3-δ (BCFN) ceramic after long-term heat treatment in different atmospheres was revealed. After heat treatment in air, the layered structure in the original interfacial reaction layer disappears, accompanied by the aggregation and growth of the interfacial products. The thickness of the reaction layer increased first and then stabilized. Under the action of the concentration gradient, the residual copper oxide diffused along the pores of BCFN matrix and continued to react with the matrix until it exhausted. The types of interfacial products remained unchanged, which were Ba2Cu2O5 and Co-Cu-O (solid solution). However, serious decomposition of interfacial products (Ba2Cu2O5) occurred due to the low oxygen partial pressure after heat treatment in argon, resulting in the formation of holes and cracks. Part of cobalt precipitated from the BCFN matrix and formed a cobalt-rich phase at the junction of Ag-Cu alloy and interfacial reaction zone. Results showed that the joint microstructure is unstable at high temperature. Controlling the amount of the interfacial products formed during brazing is key to improving the stability of the joint, which provides a theoretical support for further optimizing the sealing quality of membrane components.

Aiming to improve the surface properties of copper, a Ni-Cr-B-Si coating was fabricated by plasma transferred arc (PTA) cladding. The coating formed a good metallurgical bonding with the copper substrate, and the dilution rate was about 15.9%. The coating mainly contained γ-(Cu, Fe, Ni), Cr23C6, CrB and Ni3Si phases, which played a role of solid solution strengthening and dispersion strengthening. The hardness of the coating was significantly improved compared to the copper substrate, which was approximately 7.8 times that of the substrate. The wear resistance of the coating was 5.0 times higher than that of the copper substrate, and the wear mechanism was abrasive wear.

Titanium has excellent all-round performance, but the high cost of its production limits its widespread use. Currently, the Kroll process used to commercially produce titanium sponge is inefficient, energy-intensive, and highly polluting to the environment. Over the past few decades, many new processes have been developed to replace the Kroll process in order to reduce the cost of producing titanium and make it a common metal with as many applications as iron. These new processes can be divided into two categories: thermal reduction and electrolysis. Based on their classification, this paper reviews the current development status of various processes and analyzes the advantages and disadvantages of each process. Finally, the development direction and challenges of titanium production process are put forward.

The anodic dissolution of the high-grade nickel matte in the sulfuric acid solution was investigated at the dynamic potential and potentiostatic polarizations, and the solid products on the surface of the matte at various polarized potentials were characterized by optical microscope, scanning electron microscope and Raman spectroscopy in order to understand the passivation mechanism for the anodic dissolution of nickel matte. The results show that the oxidation dissolution activity of nickel and copper sulfides existing in the matte during the anodic dissolution decreases in the order Cu2S ​> ​Ni3S2 ​> ​NiS ​> ​CuS. When the anodic polarization potential is increasing to 1.2 ​V vs. SCE, the solid product for the oxidation of Cu2S is composed of CuS, which forms a compact layer with fine cracks covering the surface and hinders the anodic dissolution further of Cu2S underneath. While, at the same polarization potential, Ni3S2 in the matte can be anodically dissolved to form Ni2+ and elemental sulfur, and the solid product layer composing of sulfur and NiS is porous with coarse cracks, and has adverse effect on the anodic dissolution of Ni3S2 in the nickel matte.

Sodium silicate, a new type of CO2 sorbent, has a relatively low cost, but its sorption reactivity is not yet good enough. Alkali carbonate doping is commonly used as an effective means to improve the CO2 uptake reactivity of solid sorbents. In this study, sodium orthosilicate, Na4SiO4, was synthesized and mixed with 5, 10, and 20 mol% of Li2CO3–Na2CO3 or Li2CO3–Na2CO3–K2CO3 as CO2 sorbents. The promotion of alkali carbonates on Na4SiO4 in CO2 capture was characterized using thermal analyses in an 80 vol% CO2–20 vol% N2 atmosphere. The phase evolution and structural transformations during CO2 capture were characterized by in situ XRD and Raman, and the results showed that the intermediate pyrocarbonate, C2O52−, which emerged from alkali carbonates, enhanced the CO2 capture of Na4SiO4 to form Na2CO3 and Na2SiO3 from 100 °C. Isothermal analyses showed that 10 mol% of Li2CO3–Na2CO3 was the optimal additive for Na4SiO4 to attain better CO2 uptake performance. The alkali carbonates were effective in reducing the activation energy for both chemisorption and bulk diffusion, improving the cycle stability of Na4SiO4.

In this work, an innovative method was utilized to determine the AgCl(1% mol)/Ag reference electrode potential versus Cl2/Cl− at 673 K. Instead of directly measuring the chlorine electrode potential, the AgCl(1% mol)/Ag electrode potential versus Cl2/Cl− was calculated from the decomposition voltage of LiCl and the equilibrium potential of Li+/Li versus AgCl(1% mol)/Ag in a LiCl-KCl melt. The decomposition voltage of LiCl in the LiCl-KCl melt was calculated using the Nernst equation and the equilibrium potential of Li+/Li was determined by chronopotentiometry, open circuit chronopotentiometry and potentiodynamic scan techniques, and the deviation is within 5 mV. The AgCl(1% mol)/Ag electrode potential was determined to be −1.130 V vs Cl2/Cl− at 673 K. Since it does not involve direct injection of chlorine gas, this method is more convenient and safer than existing approaches. Furthermore, it also has the potential to be used to calibrate reference electrodes in a variety of melts.

Wafer-scale synthesis of p-type TMD films is critical for its commercialization in next-generation electro/optoelectronics. In this work, wafer-scale intrinsic n-type WS2 films and in situ Nb-doped p-type WS2 films were synthesized through atomic layer deposition (ALD) on 8-inch α-Al2O3/Si wafers, 2-inch sapphire, and 1 cm2 GaN substrate pieces. The Nb doping concentration was precisely controlled by altering cycle number of Nb precursor and activated by postannealing. WS2 n-FETs and Nb-doped p-FETs with different Nb concentrations have been fabricated using CMOS-compatible processes. X-ray photoelectron spectroscopy, Raman spectroscopy, and Hall measurements confirmed the effective substitutional doping with Nb. The on/off ratio and electron mobility of WS2 n-FET are as high as 105 and 6.85 cm2 V-1 s-1, respectively. In WS2 p-FET with 15-cycle Nb doping, the on/off ratio and hole mobility are 10 and 0.016 cm2 V-1 s-1, respectively. The p-n structure based on n- and p- type WS2 films was proved with a 104 rectifying ratio. The realization of controllable in situ Nb-doped WS2 films paved a way for fabricating wafer-scale complementary WS2 FETs.

The Ti-Al-Fe-V quaternary system is a very useful system for titanium alloy development. However, there are few reports on the thermodynamic description of this system. In the present work, the experimental investigation and thermodynamic description of the relative sub-systems of the Ti-Al-Fe-V quaternary system are summarized and reviewed, wherein the Ti-Fe-V system is re-assessed by using CALPHAD (CALculation of PHAse Diagrams) approach. The thermodynamic database of the Ti-Al-Fe-V quaternary system is established by extrapolating the thermodynamic descriptions of all sub- systems. Then, a method of titanium alloy design combining Mo equivalent with CALPHAD is proposed. The pseudo-binary sections with V:Fe = 3.5:1 and Al = 0.0, 3.0, 4.5 and 6.0 wt% are calculated. Finally, three different types of titanium alloys are recommended according to the new method.

The high Nb-containing TiAl-based alloy ingot beyond laboratory scale with a composition of Ti-46Al-8Nb (at.%) was prepared by a vacuum induction melting process based on a BaZrO3 refractory crucible. A round bar ingot with a diameter of 85 mm and a length of 430 mm was finally obtained, and the chemical composition, solidification pathway, microstructure and tensile properties of the ingot were investigated. The results show that the deviations of Al and Nb content along a 430 mm long central part of the ingot are approximately ±0.39 at.% and ±0.14 at.%, and the oxygen content in the ingot can be controlled at around 1000 ppm. The structure of the alloy ingot is a full lamellar structure composed of γ and α2 phases, and the thickness of the lamellae is approximately 0.53 μm. In case of the α2 phase, the surface content of the ingot is higher than the middle region and the centrical region; also, it indicated a decreasing trend. During cooling, the alloy solidified from a peritectic reaction (L + β→α) rather than the solidified via β phase (β→α). In addition to Al segregation and Nb segregation, β-phase particles associated with γ phase at the triple junction of the colonies were observed. Moreover, the tensile properties of the longitudinal-cut sample in the ingot is significantly better than those of the transverse-cut sample, with a tensile strength of up to as high as 700 MPa and a corresponding fracture elongation of 1.1%. However, the tensile strength of the transverse-cut sample is only 375 MPa, and the fracture elongation is 0.52%.

Abstract The oxidation mechanism of sulfides is the key issue during the sulphide–metallurgy process. In this study, the phase transformation and element migration were clearly demonstrated by in–situ laboratory–based X–ray diffraction (XRD) and energy–dispersive X–ray spectroscopy (EDS), respectively. The reaction sequence and a four–step oxidation mechanism were proposed and identified. The elemental distribution demonstrated that at a low temperature, the Fe atoms diffused outward and the Ni/Cu atoms migrated toward the inner core, whereas the opposite diffusion processes were observed at a higher temperature. Importantly, the unique visual presentation of the oxidation behaviour provided by the combination of in–situ XRD and EDS might be useful for optimising the process parameters to improve the Ni/Cu extraction efficiency during Ni–Cu sulphide metallurgy.

Single-atom catalysts (SACs) with maximized metal atom utilization and intriguing properties are of utmost importance for energy conversion and catalysis science. However, the lack of a straightforward and scalable synthesis strategy of SACs on diverse support materials remains the bottleneck for their large-scale industrial applications. Herein, we report a general approach to directly transform bulk metals into single atoms through the precise control of the electrodissolution--electrodeposition kinetics in ionic liquids and demonstrate the successful applicability of up to twenty different monometallic SACs and one multimetallic SAC with five distinct elements. As a case study, the atomically dispersed Pt was electrodeposited onto Ni3N/Ni-Co-graphene oxide heterostructures in varied scales (up to 5 cm x 5 cm) as bifunctional catalysts with the electronic metal--support interaction, which exhibits low overpotentials at 10 mA cm-2 for hydrogen evolution reaction (HER, 30 mV) and oxygen evolution reaction (OER, 263 mV) with a relatively low Pt loading (0.98 wt%). This work provides a simple and practical route for large-scale synthesis of various SACs with favorable catalytic properties on diversified supports using alternative ionic liquids and inspires the methodology on precise synthesis of multimetallic single-atom materials with tunable compositions. [ABSTRACT FROM AUTHOR]