The effects of particle size and macro morphology on the comprehensive properties of pellets produced by the straight-grate induration machine were investigated. The results show that the particle size of finished pellets is mainly distributed within the range of 12-16 mm, accounting for more than 90%. Intact pellets account for 59.95%, while broken pellets and cracked pellets account for 24.71% and 15.35%, respectively. The crushing strength of intact pellets rises with an increase in particle size. As for the pellets with the same particle size, the macro morphology serves as the dominant factor determining their crushing strength. It is shown that intact pellets exhibit the highest crushing strength, whereas cracked pellets show the lowest crushing strength. The essential reason for the difference in crushing strength among pellets lies in the different bonding compactness of internal hematite grains. Large-sized intact pellets undergo insufficient oxidation and possess poor uniformity in internal structure. In terms of reduction performance, intact pellets with different particle sizes have negligible differences in reduction degree. For pellets with identical particle size, broken and cracked pellets feature a higher initial reduction rate, but present no obvious differences compared with intact pellets in terms of final reduction degree, reduction swelling index and anti-pulverization performance. Broken and cracked pellets suffer degraded mechanical properties and tend to damage the gas permeability of blast furnace burden during smelting, so their feeding proportion into the blast furnace should be strictly controlled. It is recommended that the proportion of intact pellets sized 12-14 mm be preferentially increased to balance pellet strength and metallurgical properties. This research can provide theoretical support for the optimization of pellet quality evaluation system and proportion of blast furnace burden.

By adopting central composite design (CCD) of response surface methodology (RSM), a binary quadratic regression prediction model was established, with roasting temperature and oxygen concentration as influencing factors and copper leaching rate of calcine as the response value. It is shown that the prediction model presents a P value of 0.018 2, adjusted determination coefficient of 0.810 1, and signal-to-noise ratio of 7.323 6, exhibiting favorable reliability and prediction accuracy. Roasting temperature has an extremely significant effect on copper leaching rate, while oxygen concentration brings insignificant effect, and their interaction is weak. The parameters were optimized via Design-Expert software, and the optimal roasting process parameters are obtained as follows:roasting temperature of 750 ℃ and oxygen concentration of 30%. Under such optimized parameters, the predicted copper leaching rate of calcine is 97.47%, while the copper leaching rate of calcine in industrial applications reaches 98.17%.

The effects of annealing temperatures on mechanical properties, intergranular corrosion resistance and microstructure of an Al-Cu-Mg-Ag alloy sheet were investigated by tensile tests, intergranular corrosion tests, electrochemical measurements, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that with an annealing time of 4 h, the annealing temperature increased from 335 ℃ to 395 ℃ can refine the recrystallized grains of alloy sheet and promote the dissolution of residual second-phase particles, which significantly enhances the mechanical properties of the alloy. Cube texture preferentially develops in specimens annealed at 335 ℃ for 4 h, whereas Goss texture becomes the dominant texture after annealing at 395 ℃ for 4 h. It is found that higher annealing temperatures lead to increased corrosion current density and negative shift of corrosion potential, which accelerates the intergranular corrosion rate and degrades the corrosion resistance of the alloy sheet.

Sulfide solid electrolyte Li_6-xPS_5-xCl_1+x samples were prepared under varied combinations of element stoichiometry and sintering temperature. Performance characterizations were conducted to investigate the effects of processing parameters on ionic conductivity. The results reveal that the optimal parameter combination corresponds to the electrolyte with the chemical formula Li_5.35PS_4.35Cl_1.65, being sintered at 500 ℃. This electrolyte delivers a lithium-ion conductivity of 11.05 mS/cm after cold pressing at 26 ℃. For electrolytes with identical stoichiometry, the lithium-ion conductivity of electrolyte increases first and then decreases as sintering temperature rises. Under the optimal sintering temperature, the lithium-ion conductivity of electrolyte exhibits an upward trend followed by a downward trend with the increase of halogen stoichiometric coefficient (1+_x).

To enhance the rate capability and cycling stability of the high-voltage cathode material LiNi_0.5Mn_1.5O₄ (LNMO), a V-Y co-doped LNMO cathode material was synthesized via the polymer soft-template method. The effects of V-Y co-doping on crystal structure, interfacial properties, and electrochemical performance were systematically investigated. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) among other techniques, and the electrochemical properties were analyzed via galvanostatic charge-discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results indicate that V-Y co-doping induces the formation of disordered Fd3m phase by effectively regulating LNMO, facilitates the morphology evolution of spinel from regular octahedron to truncated octahedron, and constructs a coherent interface, which significantly enhances the lithium-ion diffusion rate and electronic conductivity. Moreover, V-Y co-doping reduces the Mn³⁺ content, suppresses Jahn-Teller effect and side reactions at the electrode/electrolyte interface, thereby enhancing the interfacial electrochemical stability. The 0.03V-Y sample (LiV_0.03Ni_0.47Y_0.01Mn_1.49O₄) delivers an initial discharge capacity of 132 mAh/g at a 0.1C rate, retaining 94.7% of its capacity after 200 cycles. It also exhibits superior rate capability at a high rate of 5C. This study provides a novel approach for constructing a coherent interface and synergistically optimizing the electrochemical performance of LNMO via dual-element doping.

High-wear-resistance Fe-B-W coatings were fabricated on 65Mn steel substrates via ultra-high-speed laser cladding by regulating boron content. The effects of boron content on the microstructure, microhardness and tribological properties of Fe-B-W coatings were systematically investigated by using scanning electron microscopy, X-ray diffraction, microhardness tester and friction and wear tester. The results reveal that the Fe-B-W coatings are mainly composed of α-Fe phase and Fe₂B phase, along with a small amount of W phase, Fe₃B phase and Fe₂₃B₆ phase. Iron-boron compounds increase with the rising boron content, distribute in a network structure inside the coatings and gradually coarsen. The Fe-B-W coatings can greatly elevate the microhardness and wear resistance of 65Mn steel substrate. As boron content increases, the microhardness of the coatings rises gradually, while the friction coefficient and volumetric wear rate first decrease and then increase. The coating with 3.5% boron exhibits the lowest friction coefficient, and its volumetric wear rate also drops to the lowest, only 35.8% of that of the substrate, which demonstrates that Fe-3.5B-30W coating possesses optimal comprehensive performance. It is shown that the dominant wear mechanism of Fe-B-W coatings is abrasive wear.

This paper systematically reviews the application of manganese dioxide (MnO₂) in the field of energy storage and conversion in terms of preparation techniques, modification strategies and device performance. Firstly, the regulation mechanisms of liquid-phase method, solid-phase method, sol-gel method, microfluidic etching and other approaches on the micromorphology and crystal structure of MnO₂ are elaborated systematically. As for modification strategies, the functional mechanisms of element doping, carbon-based material compositing and microstructure design (including nanostructuring and hollow structure) for improving the electrical conductivity and structural stability of materials are discussed in detail. In the aspect of device performance, the practical effects of MnO₂-based composites on elevating the specific capacity of lithium-ion batteries, optimizing the rate performance of supercapacitors, and boosting the catalytic activity of bifunctional electrocatalysts (ORR and OER) are further analyzed. On this basis, future development prospects are proposed from the perspectives of green synthesis technologies, high-loading flexible device development and multi-functional integration, aiming to provide references for the rational design of high-performance MnO₂-based energy materials.

Silicon oxide (SiO_x, 0<_x<2) anode suffer from low intrinsic conductivity, unstable solid electrolyte interphase (SEI), and mechanical stress failure caused by volume expansion during cycling. To tackle these challenges, a modification strategy was proposed, featuring the synergistic regulation of a surface fast-ion coating layer and an in-situ constructed three-dimensional (3D) carbon nanotubes (CNTs) conductive network. Nano-sized Al₂O₃ was uniformly coated on the surface of SiO_x via solid-phase mechano-fusion technology, and also converted into a fast ionic conductor layer with high ionic mobility during electrochemical activation. Subsequently, a 3D CNTs conductive network was constructed on the outer layer of the material via chemical vapor deposition (CVD). Structural and morphological characterizations reveal that the in-situ grown CNTs are tightly interwined on the particle surfaces and within the interstices, establishing efficient electron transport pathways. The synergistic effect of LiAlO₂ and CNTs greatly enhances interfacial ion transport capacity and overall electronic conductivity. Electrochemical measurements indicate that the modified SiO_x@ Al₂O₃ @ CNTs material exhibits outstanding electrochemical performance. It delivers discharge specific capacities of 1 283.2, 1 255.4, 1 236.4, 1 201.0 and 1 165.8 mAh/g at current densities of 0.2C, 0.5C, 1C, 2C and 4C, respectively. Furthermore, it retains a high specific capacity of approximately 1 000 mAh/g after 200 cycles at 0.1C, far exceeding 552.3 mAh/g of unmodified SiO_x. This study has verified the synergistic enhancement of ion/electron conductive network, and provides a promising technical solution for development of high-energy-density and highly stable silicon-based anode materials.

By adopting metal inert gas (MIG) welding, high-chromium cast iron surfacing specimens with preheating and interpass temperatures ranging from 150 ℃ to 350 ℃ were fabricated on the surface of Q345B steel plates using TDCr27-58 high-chromium cast iron flux-cored hardfacing wires. The influence of interpass temperature on macroscopic morphology, microstructure and wear performance of the surfacing layer was investigated via penetrant testing (PT), SEM and pin-on-disk wear test. The results indicate that the increase of interpass temperature improves the fluidity of molten pool and significantly reduces welding spatter and cracks. The surfacing layer mainly consists of primary dendritic austenite and intergranular eutectic M₇C₃ carbides. The average hardness of the surfacing layer rises with increasing interpass temperature, reaching 716.6HV at 350 ℃, which is 25.2HV and 39.0HV higher than that obtained at 250 ℃ and 150 ℃, respectively. The mass loss at an interpass temperature of 150 ℃ is approximately 63% larger than that at 350 ℃, exhibiting severe spalling pits and adhesive wear characteristics. A higher interpass temperature can extend high-temperature holding duration, accelerate the diffusion of C and Cr atoms, and promote the sufficient precipitation and growth of eutectic carbides, thereby improving the hardness and wear resistance of the surfacing layer.

To advance the application of direct ink writing (DIW) in SiC ceramic manufacturing, with coarse-grained SiC powder (D₅₀=44 μm) as raw material, the regulation rules of dispersant, slurry pH value, solid volume fraction and thickener on the rheological properties of slurry were systematically investigated, and high-solid-content slurry suitable for DIW was prepared. The printing parameters were then optimized based on finite element simulation, and the printability of the slurry was quantitatively evaluated via linear fluid span test. The results show that with pH of 10-11, an addition of 1.4% polyacrylic acid (PAA) dispersant can greatly reduce slurry viscosity, and lead to the maximum solid volume fraction of the slurry up to 55%. While an addition of 0.05% methylcellulose (MC) thickener can effectively improve the structural strength of the slurry, bringing in optimal comprehensive printing performance. By adopting a 1.2 mm nozzle with the maximum printing span controlled within 6.3 mm, an intact three-dimensional lattice ceramic green body can be fabricated without collapse.