JOM最新文献

Blast furnace ironmaking is a core process in steel metallurgy, where accurate prediction of the molten iron temperature is crucial for ensuring product quality, enhancing productivity, and reducing energy consumption. Aiming at the strong nonlinearity and time series dependency of blast furnace molten iron temperature, this paper proposes a soft measurement method by integrating the autoregressive integrated moving average (ARIMA) model with a Transformer-optimized long short-term memory (LSTM) model in deep learning. First, the data preprocessing stage includes identifying missing values and outliers, followed by stationarity testing and differencing. Then, ARIMA parameters are optimized by calculating Bayesian information criterion (BIC) values for parameter combinations and performing Ljung–Box tests on the residuals. Finally, linear and nonlinear components are predicted separately, a transformer-optimized LSTM model is constructed, and an ARIMA–Transformer-LSTM hybrid model is developed for final prediction. The results show that the model achieves excellent evaluation metrics: MAE = 0.0030, RMSE = 0.0036, and R² = 0.9793, outperforming both single models and their optimized models, with optimal performance at the 10-h prediction horizon.

With increasingly stringent environmental regulations in the aluminum electrolysis industry, the utilization of waste barrier materials, such as lithium, has become essential. This study elucidates the leaching behavior and kinetics of lithium, aluminum, sodium, and silicon with phosphoric acid, emphasizing the effect of acid concentration, temperature, reaction time, and solid-to-liquid ratio. Notably, optimal conditions—0.9 mol/L phosphoric acid, a 20:1 mL/g liquid-to-solid ratio, 90°C, and 1.5 h—yielded leaching efficiencies of 90.9% for lithium, 70.9% for aluminum, 37.2% for sodium, and 8.5% for silicon. Kinetic modeling demonstrated that lithium leaching was governed by chemical reaction control, while the leaching of aluminum was governed by a combination of diffusion and chemical reaction, with activation energies of 48.55 and 22.81 kJ/mol, respectively. Therefore, these findings present a viable method for recovering valuable elements from industrial waste, contributing to the circular economy in aluminum production.

In this paper, the wetting behaviors of lanthanide rare-earth inclusions in Q355 molten steel at 1873 K were investigated using the sessile drop method. It was deduced that the wetting angles of these inclusions increased in the order of La₂S₃ (95.73°) < La₂O₂S (121.58°) < LaAlO₃ (129.41°) < La₂O₃ (138.08°), wherein higher angles represent a decreasing wettability with the molten steel. In addition, poorly wettable inclusions are easily detached from the molten steel and adsorbed onto the surface of the refractory material, subsequently forming nodules through deposition or interfacial reactions. Thermodynamic calculations and critical nucleation radius analysis indicate that LaAlO₃ possesses a greater thermal stability and a nucleation advantage. The modified Kralchevsky-Paunov model calculations indicated that the capillary force between the inclusions increased with decreasing particle distance and increasing particle size. During industrial production, the nodules observed at the submerged entry nozzle were predominantly comprised of LaAlO₃, accompanied by La₂O₂S and La₂O₂, while La₂S₃ was not detected. This study, therefore, provides a theoretical foundation for understanding the formation mechanisms of rare-earth inclusions and controlling clogging during continuous casting.

The iron aluminides are intended as materials for high-temperature applications. The effect of Fe₃Al-type iron aluminide multi-alloying with silicon, molybdenum, and vanadium/tungsten on the high-temperature strength was studied. The contribution of the different strengthening mechanisms to overall strengthening during high-temperature deformation in compression was discussed. It has been shown that the addition of vanadium or tungsten significantly increases the yield stress values, especially in the temperature range of 700–800°C. The influence of heat treatment on the structure and yield stress values was also investigated. After long-term annealing at 800°C, a slight decline in yield stress values occurs for both alloys compared to the as-cast state due to the precipitation of secondary phase particles. In the case of the Fe28Al5Si2Mo1W alloy, this yield stress decrease is partly compensated by the strengthening caused by fine incoherent precipitates. After short-term annealing at 1200°C, the yield stress reaches the highest values in the entire temperature range for both alloys, Fe28Al5Si2Mo1W and Fe28Al5Si2Mo1V, due to the presumed presence of new phase nuclei verified by prolongation of annealing time.

The biocompatibility and appropriate degradation rates of zinc-based alloys have garnered increasing attention for their potential application in biodegradable implants. However, their limited mechanical performance restricts their broader utilization. This study aims to enhance the performance of Zn-3Mg-0.5Zr composites, fabricated via spark plasma sintering (SPS), for biomedical applications by examining the effects of yttrium (Y) addition on their mechanical properties and microstructure. Yttrium was incorporated into the Zn-Mg-Zr matrix in varying weight percentages (0.1–0.5 wt.%). Microstructural analysis employing X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) revealed Y-rich intermetallic phases and significant grain refinement. These phases contribute to strengthening through mechanisms such as dispersion hardening, solid-solution strengthening, and grain boundary pinning. The sample with 0.3 wt.% Y exhibited the highest ductility, with an elongation of 4.59%, whereas the composite with 0.5 wt.% Y demonstrated the greatest compressive strength (241.87 MPa) and Vickers hardness (48–50 HV). The XRD peak shifts further confirmed the lattice deformation and the onset of precipitation hardening. However, SPS-induced texturing was identified as the cause of mechanical anisotropy. The addition of Y significantly enhanced the mechanical properties of the Zn-3Mg-0.5Zr composites through synergistic strengthening mechanisms. These improvements suggest that Y-alloyed Zn composites are promising as bioresorbable implant materials. Nonetheless, further investigation into the tensile and fatigue behaviors, as well as comprehensive biological evaluations, is required to confirm their therapeutic efficacy.

To improve element segregation and solidification microstructure in the GH4169 superalloy, this study investigated the microstructure, eutectic carbides, Laves phase, and elemental microsegregation in electroslag remelting (ESR) ingots with different La contents. The results showed that, when the La content increased from 0 to 0.043 wt.%, the solidification onset temperature rose from 1333°C to 1341°C, while the solidification termination temperature increased from 1178°C to 1189°C. The secondary dendrite arm spacing at the ingot center decreased from 68.7 μm to 63.1 μm, and the area fractions of NbC and Laves phase in the as-cast structure decreased by 20.59% and 22.22%, respectively. Nb exhibited the most severe microsegregation in the GH4169 alloy, followed by Mo. With La content increasing from 0 to 0.043 wt.%, the microsegregation indices of Nb, Mo, Cr, Fe, and Ni decreased. At the early stage of the solidification process, La-containing inclusions acted as heterogeneous nucleation sites, increasing the nucleation rate. At the late stage of solidification, dissolved La atoms in the liquid metal enriched at the front of solid–liquid interface, enhancing constitutional supercooling and restricting dendrite growth.

Laser powder bed fusion (LPBF) processing produces metal parts with unique geometry and properties; however, it also creates a lot of unused or waste powder after printing. This waste powder can make the process unsustainable unless methods of handling and recycling the powder are used. Quantifying the effects of powder recycling on the parts' microstructure and mechanical properties is highly important, particularly if the reused powder is subject to non-optimal powder handling, as would be the case in distributed manufacturing. This study evaluates the quantifiable impact of non-optimally stored powder properties on the degradation mechanism of microstructure and mechanical properties. It is observed that powder particle size and oxidation increase, leading to increased flowability and laser absorption of the powder bed, which increases melt pool depth by 11% and porosity by 0.4%. The parts have comparable surface roughness among the reused and virgin cases; however, lower microhardness due to increased columnar dendrites, while tensile properties decline due to increased porosity.

This study investigates the machinability of TiN-coated WC tools in dry turning of SUS416 stainless steel, directly comparing their performance with uncoated WC tools. The TiN coating’s microstructure and mechanical properties were characterized by SEM, EDS, nanoindentation, and wear testing. Turning experiments conducted at a cutting speed of 150 m/min, a feed rate of 0.2 mm/rev, and a depth of cut of 1.5 mm. TiN-coated tools exhibit high hardness, low friction, and improved oxidation resistance, resulting in 43% lower flank wear and an extended tool life by 150% compared with uncoated tools. The coating minimizes interface friction, reducing surface roughness from 3.96 µm to 2.59 µm. Under high-speed machining conditions, TiN-coated tools exhibit more uniform wear without edge cracking and produce regular, uniform chips with reduced adhesion, which enhances cutting stability. This work integrates micro-mechanical and tribological theory with the actual high-thermal-load dry turning behavior. The study also provides annotated wear and chip images as part of the dataset, which can serve as a basis for artificial-intelligence applications in automated wear detection and machining optimization. These findings demonstrate that TiN coatings effectively enhance tool durability and cutting performance in dry turning for high-precision, high-efficiency applications.

This study focused on the synthesis of two low-cost, highly crystallized mesoporous nanosodalites from waste materials. SOD@DWTS/SiO₂ was produced from drinking water treatment sludge (DWTS) and silicon dioxide (SiO₂), while SOD@DWTS/FA was synthesized from DWTS and fly ash (FA). This approach valorizes waste, reduces landfill use, and lowers raw material costs. By adjusting the Si/Al ratio based on the differing waste compositions, the synthesis controlled the amounts of SiO₂ and FA added. The resulting sodalites exhibited well-defined crystalline structures and spherical morphology, although their specific surface areas varied. Variations in the Si/Al ratio and substitution of commercial SiO₂ with fly ash notably influenced material properties, including crystallinity. Both sodalites showed promising adsorption of AR97 dye, with maximum capacities of 90.91 mg/g for SOD@DWTS/SiO₂ and 55.56 mg/g for SOD@DWTS/FA at pH 2 and ambient temperature, following the Langmuir model and demonstrating high efficiency. This work highlights the potential of transforming industrial by-products into valuable materials, contributing to waste management, materials science, and circular economy practices.

Treatment of fluorine-containing wastewater remains challenging. This study proposes a closed-loop method involving acidification, adsorption, alkaline elution, and regeneration for fluoride removal from wastewater using anhydrous zirconium sulfate (Zr(SO₄)₂) as a defluorination agent. Firstly, Zr(SO₄)₂ was synthesized via acidification of ZrO₂ with sulfuric acid (H₂SO₄). Secondly, under the optimal conditions of pH 4, temperature of 60°C, adsorption time of 60 min, and Zr(SO₄)₂ dosage of 1.2 g/L, the fluoride removal rate of 96.52% was achieved. The fluoride removal residue was eluted with sodium hydroxide solution, yielding a maximum fluorine elution rate of 99.78% at 1 mol/L NaOH. Subsequent re-acidification of the eluted residue with H₂SO₄ regenerated the defluorination agent. Over 10 cycles, the fluoride removal rate remained consistently above 90%. Adsorption kinetics analysis indicated that the process followed the pseudo-second-order kinetic model and the Langmuir model, with a maximum adsorption capacity of 139.86 mg/g. Material characterization revealed that fluoride adsorption on Zr(SO₄)₂ occurred mainly through chemical adsorption, forming a ZrF₄ conjugate. These results demonstrate that Zr(SO₄)₂ is a promising defluorination agent for industrial wastewater treatment, enabling effective fluoride removal with low consumption.