JOM最新文献

This study investigates the impact of annealing time on the structural, optical, and mechanical properties of ZnO thin films annealed at 400°C in air for 10 min to 2 h. The results show that even a short annealing of 10 min significantly improves optical transparency, with further enhancement observed as annealing time increases. Crystallite size increased with longer annealing, indicating better crystallinity. The obtained refractive index values, ranging from 1.9 to 2, indicate a compact material structure. The optical bandgap (E_g) increased from 3.76 eV to 3.90 eV with annealing time. A notable surface plasmon resonance (SPR) effect, shifting to the visible range, was observed. A new method was developed to estimate the size of metallic Zn nanoparticles contributing to the SPR effect. Mechanical properties, such as hardness, Young's modulus, and resistance to plastic deformation, improved with longer annealing times. These findings highlight the potential of ZnO films for various applications due to their enhanced optical and mechanical performance.

The additive manufacturing of hard-to-process intermetallics, such as the Ti-23Al-25Nb alloy (O-alloy), poses significant challenges but is critical for expanding their industrial applications. This study identifies the optimum laser powder bed fusion (L-PBF) parameters, build platform temperature, and aging treatment required to produce high-performance, crack-free O-alloy for demanding applications. The effect of L-PBF process parameters, including platform preheat temperature and subsequent aging treatment on the relative density, defects, microstructure, phase composition, and mechanical properties of orthorhombic titanium aluminide, Ti2AlNb, is investigated. Build platform preheating at 600°C and high volumetric energy density (VED) in the range of 37–139 J/mm³ results in a keyhole porosity and cracking due to excessive energy input. Increasing the substrate temperature to 700°C, under optimized process parameters with VED in the range of 22–37 J/mm³, produces a crack-free build with a relative density of 99.7%. A reduction in laser scanning speed increases the fraction of the O-phase, thereby enhancing the high-temperature strength. In addition, post-aging treatment at 800°C for 30 min improved the strength and ductility of the O-alloy at room and elevated testing temperatures of 600 and 700°C. The effect of microstructure on the mechanical properties of the O-alloy is discussed.

A new Zr-based bulk metallic glass (Zr_55.1Cu_39.9Al₅) with a large supercooled liquid region and outstanding mechanical properties was successfully fabricated in both ribbon and rod forms via melt spinning and copper mold casting. This simple ternary alloy exhibits excellent glass-forming ability and high thermal stability, as indicated by a distinct glass transition temperature (T_g = 673 K) and an onset crystallization temperature (T_x1 = 739 K), resulting in a wide supercooled liquid region (ΔT_x = 66 K). Upon heating, the alloy undergoes a multi-step crystallization sequence: [am] → [am′ + Cu₁₀Zr₇] → [am″ + Cu₁₀Zr₇ + CuZr₂] → [Cu₁₀Zr₇ + CuZr₂]. The as-spun ribbons exhibit superior mechanical performance, with a high hardness of 464 HV, an elastic modulus of ~ 80 GPa, a tensile fracture strength of 1326 MPa, and notable bending ductility. Furthermore, fully amorphous rods with diameters up to 1.5 mm were obtained, displaying a high compressive fracture strength of ~ 1592 MPa and a total elongation of about 9.3%. These results confirm the alloy’s exceptional combination of thermal and mechanical properties and demonstrate its promise for advanced structural and functional applications requiring high strength, hardness, ductility, and processability in bulk form.

Industrial processes consume nearly 26% of global energy, with over half lost as waste heat. To address this challenge, we present a novel hydrogen-based thermochemical energy storage (TCES) system that combines magnesium hydride (MgH₂) doped with 3 wt.% Ti and 2 wt.% V, along with a nanostructured TiO₂-V₂O₅ catalyst doped with 3 wt.% Ni. This hybrid design enhances hydrogen absorption/desorption kinetics by 31.2%, reduces activation energy by 21.4%, and achieves a storage capacity of 8.4 wt.% at 350–500°C. When integrated with 600°C industrial waste heat, the system demonstrated > 95% hydrogen retention across 100 cycles and reduced CO₂ emissions by 40% compared to fossil-fuel heating. Numerical validation using ANSYS Fluent and Aspen Plus confirmed experimental performance with < 5% deviation. The results establish the first scalable demonstration of a hydrogen-based TCES system that couples advanced material engineering with industrial waste heat utilization, offering a practical pathway toward zero-carbon, high-efficiency thermal energy recovery.

Converter steelmaking technology plays a pivotal role in the production of clean steel, energy efficiency, and low-carbon steelmaking. Notably, the medium converter represents a substantial proportion of the equipment in steel plants. However, the effectiveness of bottom-blowing stirring is a limiting factor in the smelting efficiency of medium converters. This work introduces a novel, systematic approach to bottom blowing that addresses the issue of inadequate stirring in medium converters. The optimal bottom blowing arrangement for medium converter is at 0.3–0.6D with 15° included angle, which results in the most intense stirring effect within the molten bath. Compared to ordinary bottom-blowing configurations, the novel arrangement leads to a 2.2% reduction in the dead zone ratio, a 9-s reduction in mixing time, and a 26% increase in the intense stirring zone ratio. These results provide both theoretical insights and practical guidance for optimizing bottom-blowing processes in medium converters.

Sepiolite, a natural strategic clay mineral within the phyllosilicate group, is utilized in numerous applications because of its physical, and rheological properties. In particular, outstanding rheological properties are utilized in areas including drilling mud, paint, cosmetics, adhesives, etc. Several studies have been performed for the purification of clays, such as air classification, calcination, hydrocyclone, and flotation, for different purposes. In this study, relatively easy physical upgrading methods involving hydroxyclone, Falcon, and shaking table have been tested with the aim of obtaining a high-viscosity sepiolite product for rheological applications. It is shown that dispersion time, particle size, and pH are the most critical parameters in the viscosity development of sepiolite. The results indicate that, depending on the dispersion time of the raw HS1 sepiolite sample used in this study, the highest quality rheological material remains in the size range of – 2 mm to + 1 mm. Below – 0.1 mm, the viscosity value of the sepiolite sample decreased to its lowest value of 6000 cP. The pH-dependent viscosity measurements of a raw HS1 sepiolite sample exhibited the highest viscosity value of 13,000 cP at its natural pH of 8.5. Polyacrylic acid sodium salt (PAA) is the most effective dispersing agent in the decantation process for the enrichment of HS1 sepiolite samples. Among the three gravity/sizing beneficiation techniques tested, the middlings product of the shaking table achieved the highest quality sepiolite product of 17,000 cP with 49.2 wt.% using the size range of – 2.83 mm to + 1 mm; this material is suitable for high-grade rheological applications.

This study examines the influence of aluminum oxide (Al₂O₃) nanofluid concentration under minimum quantity lubrication (MQL) on the machinability of AISI 304 stainless steel. Cutting force and surface roughness were the primary response parameters, evaluated using a structured L27 orthogonal experimental design. Experiments tested three levels of cutting speed, feed rate, and nanoparticle concentration. Analysis of variance (ANOVA) showed that nanoparticle concentration and cutting speed were the most significant factors, markedly reducing both cutting force and surface roughness, while interaction effects were statistically insignificant. Complementing the experimental analysis, an artificial neural network (ANN) model, employing the Levenberg-Marquardt (LM) algorithm, was developed to predict responses based on process parameters. The ANN achieved excellent prediction accuracy, with R² values > 0.998 and minimal mean squared error, demonstrating its ability to capture complex nonlinear relationships. The model generalized effectively across training, validation, and testing datasets, with residual and performance plots confirming convergence and reliability. The combined application of ANOVA and ANN provides a robust process analysis and optimization methodology. This integrated approach identifies key influencing factors and accurately predicts machining outcomes, thereby contributing to developing intelligent and sustainable strategies for machining difficult-to-machine materials.

The effects of electric pulse treatment (EPT) on the mechanical properties and corrosion resistance of Al-Zn-Mg-Cu alloys were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers hardness testing, and electrochemical workstation analysis. The results indicate that EPT effectively refines the grain structure and mitigates elemental segregation, thereby enhancing both mechanical performance and corrosion resistance. Under a pulse voltage of 500 V, the average grain size of the alloy was reduced from 74 μm to 43 μm, and the area fraction of the η(MgZn₂) phase decreased from 11.68% to 7.13%. Texture analysis revealed that the predominant orientations after treatment were {111} <011> and {111} <166> , with an increased fraction of equiaxed grains and low-angle grain boundaries, and the generation of a coarse η phase during solidification was suppressed. The microhardness of the alloy matrix increased from 130 HV_0.2 to 166 HV_0.2, the tensile strength improved from 131 MPa to 206 MPa, and elongation rose from 2.31% to 5.17%. Electrochemical measurements showed that the corrosion potential shifted positively from − 0.862 V to − 0.754 V, while the corrosion current density dropped from 8.362 × 10⁻³ A cm⁻² to 2.46 × 10⁻⁶ A cm⁻², a reduction of approximately three orders of magnitude.

This paper reviews current observations regarding processing conditions for oxide dispersion-strengthened steels consolidated through additive manufacturing techniques. Variations in ODS steels observed across process parameters include changes in grain size, grain texture, oxide size, density of oxides, porosity, melt pool characteristics, and mechanical properties. These properties were then compared across techniques to understand which techniques and processing conditions lead to the highest strength, ductility, and oxide density. Current literature suggests that a mix of grain types, in the form of either morphology or phase, can significantly increase the strength of printed ODS steels. Meanwhile, the most ductile samples, regardless of consolidation technique or matrix material, were made from feedstock with oxide additions located on the powder surface. Reported grain and oxide sizes were plotted against the ratio of laser power to scan speed, volumetric energy density, and normalized enthalpy. No strong correlation between these values and microstructural features was observed. The plots that were made suggest that a larger data set, more in-depth representative equations, and more defined material properties as a function of specific feedstock used are necessary to determine a value that can be correlated to the printed ODS steel microstructure.

As fuel costs rise and energy scarcity intensifies, efficient utilization of by-product gases from the steel industry has become a key technological path for energy conservation and carbon reduction in blast furnaces. This study proposes injecting various by-product gases from steel production into blast furnaces. By increasing oxygen-enrichment and coal-injection rates, this approach aims to reduce coke consumption, lower the coke ratio, and boost output. However, the environmental impact and specific effects on CO₂ emissions of injecting reducing gases into blast furnaces without prior decarbonization require systematic investigation. To address this, this study develops a life cycle assessment (LCA) model for blast furnace hot metal production. It analyzes the environmental impacts and carbon footprint characteristics of hot metal production under different by-product gas conditions. The results indicate that spraying untreated reducing gases can lead to different trends in the characterization results of different impact categories. Among them, the potential for global warming and energy intensity is most significantly affected. Among the four scenarios examined, the coke oven gas (COG) injection scenario has the least environmental impact. Specific CO₂ emission totals for the four scenarios are 1697.9 kg/ton, 1721.2 kg/ton, 1747.7 kg/ton, and 1678.6 kg/ton. In the COG injection scenario, direct emissions from the blast furnace process decrease to 562.8 kg/ton, 610.5 kg/ton, and 571.4 kg/ton, reductions of 17.87%, 10.92%, and 16.63%, respectively. Indirect emissions from the oxygen-enrichment process increase to 243.1 kg/ton, 229.9 kg/ton, and 243.1 kg/ton. Additionally, CO₂ emissions from coking and oxygen-enriched blasting decrease, while those from sintering remain relatively stable.