Aiming at the mechanical vibration problem caused by the coupling between the flexible deformation of the long-cantilever boom structure and the dynamic characteristics of the gear-rack transmission system during the operation of the hot metal deslagging robot, this paper focuses on conducting a systematic rigid-flexible coupled dynamic modeling and vibration characteristic analysis. By integrating multi-body dynamics and finite element analysis for co-simulation, the dynamic response of the flexible boom during the swinging phase is accurately captured. Furthermore, based on modal coordinate analysis, the vibration generation mechanism and propagation characteristics are revealed.
Precise control of jet cooling rate is critical to optimizing the on-line heat treatment process for steel rails. Numerical simulation can effectively shorten the research cycle and reduce costs. Most existing simulations of jet cooling for high-temperature steel are based on static nozzles and stationary rails, which deviate from the continuous movement of rails in actual production and compromise simulation accuracy. To improve the consistency between simulation and real working conditions, this study adopts sliding mesh and overset mesh techniques to numerically simulate jet cooling of a moving high-temperature steel block. Reciprocating experiments are conducted to compare simulation results under three conditions—static, moving with sliding mesh, and moving with overset mesh—with experimental data. Results show that the average relative errors compared with experiments are 18.01 %, 14.88 %, and 13.36 % , respectively, and the relative deviations of cooling uniformity standard deviation against experimental data are 92.59 %, 7.41 %, and 22.22 %, respectively. In conclusion, the overset mesh model yields higher accuracy in overall temperature field prediction, while the sliding mesh model achieves better agreement with experimental results in terms of cooling uniformity. Both dynamic mesh methods improve consistency with actual working conditions compared with the stationary model.
Pellets were formed by adding carbon to laterite nickel ore leaching residue in the laboratory and then reduction roasting was carried out. The effects of reduction conditions such as the ratio of reducing agents, reduction temperature, and reduction time on the products of direct reduction iron (total iron content and iron recovery rate) were studied. The research results show that under the conditions of a reducing agent (coal powder) ratio of 16 %, a reduction temperature of 1200 °C, and a reduction time of 40 minutes, the total iron content of directly reduced iron is 93.10 %, and the iron recovery rate is 96 %.
With the rapid development of outdoor sports, marine operations, and special work clothing, the performance failure of clothing zippers in high wear-corrosion coupling environments has become increasingly prominent. Traditional metal zippers have low surface hardness and insufficient corrosion resistance, making it difficult to meet the long-term use requirements under complex working conditions. This paper proposes a surface engineering strategy based on laser cladding technology, which in-situ prepares a Stellite 12 cobalt-based alloy coating on the surface of 304 stainless steel zipper teeth. The microstructure, wear resistance, and corrosion resistance of the coating are systematically studied. The results show that the laser cladding coating forms a metallurgical bond with the substrate, forming a composite structure of "gamma-Co solid solution matrix + hard carbide eutectic". The microhardness of the coating is significantly improved; friction and wear tests show that its wear loss is greatly reduced compared with the substrate, and the corrosion current density decreases by an order of magnitude in the corrosive environment, demonstrating excellent comprehensive performance. This study provides a feasible material and process solution for improving the service performance of zippers in harsh environments, and has important theoretical value and practical significance for promoting the development of high-end functional clothing.
This study takes simulated materials of bronze cultural relics (coppertin alloy-plated quartz crystal oscillators) as the research object, adopts the Quartz Crystal Microbalance (QCM) technology, and systematically investigates the effects of different temperature and humidity conditions on their corrosion. Three temperature levels (20 degrees C, 25 degrees C, and 30 degrees C) and corresponding gradient levels of relative humidity were set in the experiment. By monitoring the changes in frequency and mass of the quartz crystal oscillators, the corrosion kinetic rules were analyzed. The results show that temperature and humidity exert a significant influence on the corrosion of the simulated materials: under constant temperature, the higher the relative humidity, the thicker the water film on the metal surface, the greater the dissolved amount of pollutants, and the faster the corrosion rate; under constant humidity, an increase in temperature will accelerate the corrosion reaction, and the higher the relative humidity, the more pronounced the accelerating effect of temperature. Based on the experimental data, a classification standard for temperature and humidity levels was formulated. It is recommended that the long-term storage environment of bronze cultural relics in museums should be controlled at a temperature of (20-25) degrees C and a relative humidity below 60 %. The conclusions of this study provide a scientific basis for museums in tourist scenarios to precisely regulate temperature and humidity, optimize passenger flow management, and improve protection measures, thereby facilitating the achievement of a win-win situation for the coordinated and sustainable development of bronze cultural relic protection and the tourism industry.
The present study investigated the impact of Zr microalloying on the solidification mechanism and rate of cast-rolled Al-Mg-Si aluminum alloy, using differential scanning calorimetry, light microscopy, and PandatTM thermodynamic calculations. The molecular dynamics models of three different systems were established: Al-pure, Al-0.1Zr and Al-0.3Zr. The results revealed that an optimal amount of Zr effectively reduced the nucleation barrier at the atomic level during alloy solidification. This reduction facilitated the formation of critical nuclei, promoted the transformation of hexagonal close-packed clusters into face-centered cubic clusters, altered the mechanism of grain nucleation and growth, and enhanced the solidus temperature of the cast-rolled alloy. Consequently, the temperature range of the solid-liquid two-phase region was narrowed, leading to a substantial increase in the alloy’s solidification rate. These atomic-scale findings enhance understanding of Zr's role in solidification control, offering a basis for designing high-performance aluminum alloys and guiding industrial twin-roll casting processes.
In this work, MgO transparent ceramics were fabricated via spark plasma sintering (SPS) with Y2O3 as a sintering aid. The effects of sintering temperature, holding time, and Y2O3 content on the densification, microstructure, and optical transmittance of the ceramics were systematically investigated. Results indicate that optimizing SPS process parameters combined with an appropriate Y2O3 addition remarkably enhances the performance of MgO ceramics. Specifically, when sintered at 1350 °C for 10 min with 1.5 wt % Y2O3 doping, the MgO ceramic achieves high relative density and a maximum in-line transmittance of 75.35 % (mid-infrared range). Mechanistically, based on XRD lattice parameter analysis and SEM microstructural observations, Y3+ ions (ionic radius: 0.89 Å) are inferred to dissolve into the MgO lattice (Mg2+ ionic radius: 0.72 Å), inducing lattice distortion that is favorable for densification and grain growth inhibition. Excess Y2O3 (beyond 1 wt %) tends to segregate at grain boundaries, exerting a grain refinement effect via the Zener pinning mechanism. This study provides an effective strategy for the low-temperature fabrication of high-transmittance MgO transparent ceramics, thereby laying a solid foundation for the development of infrared (IR) window materials.
This study investigates the rock-breaking process of pneumatic rock drills using the Drucker–Prager (D–P) strength criterion. A numerical drilling model comprising a rigid impact piston, a rigid drill bit, and D–P rock material was developed in ANSYS LS-DYNA. A sensitivity analysis was performed to evaluate the influence of key material parameters on the maximum impact force between the drill bit and rock. Mesh independence was confirmed with an optimal rock element size of 1.000 mm. The effects of maximum principal strain at failure, rock density, elastic shear modulus, Poisson’s ratio, friction angle, dilation angle, and cohesion were examined over a variation range of ±10 % to ±50 %. Results show that the elastic shear modulus has the strongest influence on the maximum impact force, exhibiting an approximately linear positive relationship. The maximum principal strain at failure also significantly affects impact force, whereas density and Poisson’s ratio produce non-monotonic responses. Friction and dilation angles show strong sensitivity within a limited angular range, while cohesion has only a minor effect. Furthermore, the elastic shear modulus remains the dominant parameter even under different failure-strain conditions, indicating an interaction between stiffness and failure characteristics. The findings provide guidance for predicting drilling forces, optimizing drill-bit design, and improving drilling efficiency through better matching of rock properties and drilling parameters.
Pipe organs rely on the long-term dimensional stability of metal tubes to maintain accurate intonation, while traditional tin-lead alloy tubes are susceptible to room-temperature creep, which may lead to irreversible deformation and pitch drift. This theoretical feasibility study (without new experimental testing or acoustic validation) explores the potential of the newly developed Ti60 high-temperature titanium alloy as an organ pipe material from the perspective of creep resistance. The analysis is based on published high-temperature creep data and physically constrained mathematical extrapolation. Published creep data for Ti60 alloy at 550 °C indicate a typical three-stage creep behavior, including primary, secondary, and tertiary creep stages, with a minimum steady-state creep rate of 0.04 h⁻¹ under the reported test conditions. Based on the creep deformation mechanism dominated by dislocation motion and on the Arrhenius relationship describing the temperature dependence of creep rate, the study suggests that Ti60 may exhibit extremely low creep deformation under low-stress room-temperature conditions. It should be emphasized that this conclusion is based solely on theoretical extrapolation and does not represent experimental verification of actual service performance. Using an established creep constitutive model, mathematical extrapolation, and mechanistic analysis of high-temperature creep behavior, this work provides a preliminary theoretical assessment of the feasibility of Ti60 as an alternative organ pipe material in terms of creep resistance. The results suggest a potential direction for future research aimed at reducing long-term dimensional deformation caused by room-temperature creep and supporting the preservation of pipe organ cultural heritage.
Aimed at optimizing resource utilization, this study leverages finite element analysis (FEA) to compare integral and assembled tamping picks—both are pivotal components in railway ballast tamping machines prone to wear. Traditional integral picks, cast/forged with embedded wear-resistant alloys, suffer from material waste, as they compel full replacement upon head wear. The FEA involved static and modal analyses, where the former revealed that the assembled picks exhibited a maximum equivalent stress 27.5 MPa higher than the integral ones, free from any significant stress concentration. The integral picks concentrated stress on upper/lower surfaces, incurring the under-utilization of mid-section material. The modal analysis compared resonance in the first 10 vibration modes. For the integral picks, the 10th mode demonstrated a maximum amplitude (34.2 mm, 6815.5 Hz) localized at the head. The assembled picks possessed higher amplitudes in the 3rd (69.3 mm), 4th (69.4 mm), 8th (65.6 mm), and 9th (64.6 mm) modes—all on the pole. As manifested by the results, the integral picks’ material waste and stress inefficiency are curtailed by the assembled designs. Notwithstanding their slightly higher static stress, the assembled picks show dynamic behavior (higher amplitudes on the pole vs. head) that aligns better with wear patterns, so that the localized replacement is feasible. Consequently, the assembled tamping picks, supported by FEA results, present a preliminary numerical analysis for more economical solution for railway maintenance.
The production of high-silicon alloys in submerged arc furnaces (SAFs) is among the most energy-intensive processes in ferroalloy metallurgy. This paper reports a staged improvement of technological efficiency during industrial FeSi75 production in a six-electrode SAF. Performance was assessed using daily productivity, specific electricity consumption, and stability of silicon content in the product. The analysis used daily production records (electricity and product mass aggregated over 24 h; chemical composition calculated as a mass-weighted average of product containers). Shutdown and start-up days were excluded using current-and power-based criteria. In 2020, the structure of carbon reductants was modified, which coincided with a decrease in specific electricity consumption by approximately 120 kWh/Mg relative to 2016-2019. In 2023, the bath depth was reduced from 2500 mm to 2200 mm, and the operating point was intensified (active power from 5.7 MW to 6.1 MW; electrode current from 28 kA to 31 kA), resulting in a further reduction in specific electricity consumption and an increase in daily productivity. Throughout the analysed period, the silicon content remained stable at about 75 wt. % Si. In the investigated stage, the power-supply system (transformers and short network) was not modernised, indicating that measurable KPI improvements can be achieved through process-and construction-side actions and operating-regime optimisation under industrial constraints.
This study presents a novel methodology that combines machine learning with first-principles calculations to efficiently screen austenitic stabilizing elements. Correlation analysis identified the lattice constant as a critical factor influencing the stability of austenitic doping systems. Subsequently, the random forest, support vector regression, and AdaBoost models were evaluated, among which the random forest achieved the highest prediction accuracy ( R² = 0.748). Furthermore, SHapley Additive exPlanations was employed to interpret the model, further verifying the potential role of the lattice constant. Based on the above studies, Cr, Ni, and Mn were identified as doping elements. Finally, the first-principles calculation is employed to verify the prediction results of the machine learning. First-principles calculation results revealed that the austenite doped with Cr exhibits the lowest system energy (-29609.59 eV) and solid solution energy (-11.795 eV). Electronic structure analysis (including charge density difference and density of states) reveals the underlying mechanism: the larger the lattice constant of the doping atom, the weaker its interaction with the iron atoms, as specifically manifested by the reduction in electron cloud density and covalent bonding. These findings not only confirm the scientific validity of the proposed integrated machine learning and first-principles approach but also offer important guidance for the rational design of high-performance austenitic materials.
This study investigates the corrosion protection of 310S stainless steel by Al₂O₃ coatings prepared using an ozone-assisted atomic layer deposition (ALD) process. A dense and uniform Al₂O₃ coating with a thickness of approximately 150 nm was deposited on the steel surface. The coating morphology, phase composition, adhesion, high-temperature oxidation resistance, and corrosion behavior were evaluated using SEM/EDS, AFM, XRD, Vickers indentation, immersion tests, and electrochemical measurements. The results show that the ALD Al₂O₃ coating effectively covers surface defects, exhibits good adhesion to the substrate, and significantly improves corrosion resistance in chloride-containing and acidic media. The coated sample also maintains structural integrity after oxidation at 800 °C, indicating improved high-temperature stability and reduced chromium outward diffusion. These results demonstrate that ozone-assisted ALD Al₂O₃ coating is a promising surface protection method for 310S stainless steel used in outdoor fencing and ecological protection applications.
Copper radiators are widely used in automobiles due to their high thermal conductivity. However, they are prone to corrosion, which can lead to reduced vehicle performance. This study aimed to identify the chemical components of copper radiator parts and evaluate corrosion inhibition by keruing oleoresin as a natural, eco-friendly coating material. The research involved determining the chemical elements of copper radiator parts using emission spectroscopy and assessing the corrosion rate of copper radiator parts coated with keruing oleoresin in distilled water conditions using electrochemical tests. The results showed that a 5 % concentration of keruing oleoresin provided the best corrosion inhibition, with an OCP of 0.124 V, a corrosion rate of 0.00673 mm/year, and an inhibition efficiency of 88.15 %. The study demonstrates the potential of keruing oleoresin as a natural corrosion inhibitor for copper radiators, helping prevent corrosion and maintain radiator efficiency.
To address the specific performance requirements of lightning protection materials for ancient buildings, isothermal hot compression experiments were conducted with forged 316LN austenitic stainless steel employing a Gleeble-3500 thermal-mechanical simulator. The test matrix covered a strain rate range of (0.001-1) s-1, a deformation temperature interval of (1273-1423) K, and a maximum true strain of 0.7, targeting a comprehensive exploration of the material's high-temperature flow behaviors. A flow stress constitutive model was constructed by integrating the Arrhenius equation, and its predictive performance was validated through rigorous comparison with experimental data. Key observations indicate that under constant strain rate conditions, elevated deformation temperatures lead to reduced compressive stress in the material. This phenomenon is closely linked to enhanced atomic mobility and accelerated dynamic recrystallization, which collectively induce softening effects. In contrast, at a fixed temperature, higher strain rates result in increased compressive stress, as rapid deformation intensifies work hardening to an extent that outweighs dynamic softening. The true stress-true strain curves exhibit a distinct three-stage evolution, rapid ascent, gradual growth, and stabilization with the final stable phase arising from a dynamic equilibrium between work hardening and dynamic softening mechanisms. This research delivers essential theoretical foundations and practical engineering guidance for refining the hot working processes of 316LN stainless steel specifically tailored to the fabrication of ancient building lightning protection systems.
During the copper matte converting process, slag is produced. Owing to its valuable components, it is returned to the shaft furnace, where copper concentrates are smelted. Recycled slags should not contain excessive amounts of fine fractions, which reduce the permeability of the furnace charge and may be entrained with the gas stream. This study aimed to investigate the possibility of using a fine fraction of converter slag as an addition to copper concentrate briquettes. The results indicate that the optimal addition, in terms of briquette strength, is 6 % converter slag with a particle size of (0-1) mm. The presence of fayalite in the slag causes even such a small addition to reduce the final melting temperature by approximately 30 degrees C compared with the slag-free charge. Consequently, copper concentrates can be smelted with reduced coke consumption, while the resulting shaft slag exhibits lower viscosity and, therefore, reduced copper losses.
This paper studied the corrosion resistance of W600 tool steel in artificial rainwater and 3.5 % NaCl solution. The equilibrium phase diagram was determined from the material’s chemical composition, with calculations and thermodynamic simulations carried out using Thermo-Calc software, enabling accurate prediction of stable phases as a function of temperature and composition. According to the obtained projections, the solidification and precipitation of individual phases at characteristic temperatures was read. Following the completion of the electrochemical measurements, insight into the corrosion behavior of the tested sample was provided. Electrochemical tests showed a decrease in charge transfer resistance and an increased corrosion rate in the 3.5 % NaCl solution, indicating inadequate resistance in a chloride-containing solution, attributed to the formation of a thin oxide layer caused by the attack of chloride ions from the solution. Metallographic analysis confirmed the occurrence of slowly progressing pitting corrosion in chloride solution, while no significant changes were observed after testing in artificial rainwater. The lower rate of pitting corrosion was attributed to the martensitic microstructure with fine needle-like morphology with uniformly distributed carbides in the W600 tool steel. Such investigations are essential for understanding material behavior in aggressive environments and for reliably predicting its durability in real applications.
Corrosion poses pervasive threats to daily-life infrastructure, causing severe economic losses and potential safety hazards, which underscores the urgent demand for high-performance anti-corrosion coatings. This study focuses on enhancing the corrosion resistance and service reliability of phosphated Q235 carbon steel by developing an epoxy coating modified with hydrophobic nano-silica, thereby contributing to the reduction of corrosion-induced risks and potential economic losses in practical applications. The coatings were systematically characterized using scanning electron microscopy, static contact angle measurements, thermogravimetric analysis, and electrochemical techniques. The results demonstrate that the nano-silica-doped coating significantly improves the corrosion protection performance, thermal stability, and surface hydrophobicity of phosphated Q235 steel, with the water contact angle increasing at higher nano-silica loadings. This work confirms that hydrophobic nano-silica modification represents an effective strategy to optimize epoxy anti-corrosion coatings, which is beneficial for prolonging service life and improving the operational safety of carbon steel components in service environments.
Surface electromyography (sEMG) electrodes are critical components for signal acquisition; their material properties directly dictate the stability and accuracy of the recorded signals. To address the limitations of traditional electrodes, such as poor flexibility and signal interference, this study prepared a gel electrode based on MXene/PEDOT:PSS/PAAm. Key properties, including conductivity, adhesion, and stretchability, were systematically analyzed. Results indicate that an optimal PEDOT:PSS to MXene ratio of 6:4 yields a composite conductive material with a sheet resistance as low as 10.3 Omega/sq. Performance tests demonstrated that the electrode's adhesion strength to porcine skin tissue reached (49.10 +/- 1.25) kPa. Furthermore, its contact impedance with human skin was significantly lower than that of standard Ag/AgCl electrodes in the (0.1-1000) Hz frequency range. In sEMG acquisition experiments, compared to Ag/AgCl electrodes, the prepared electrode exhibited a higher signal-to-noise ratio (SNR), lower root mean square error (RMSE), a smoother signal waveform, and a more stable baseline. The electrode demonstrates excellent conductivity and adhesion, providing a high-performance solution for wearable sEMG monitoring equipment.
Hot-rolled steel strips play a crucial role in industrial settings, where the accurate identification of surface defects is essential to uphold product quality and safety. This study introduces an enhanced version of the YOLOv8 model by integrating an Efficient Multi-scale Attention (EMA) mechanism into the C2f module, thereby creating the C2f_EMA module. This integration aims to improve the adaptive feature representation in both channel and spatial dimensions. The EMA mechanism serves to emphasize critical defect areas, suppress irrelevant background details, and enhance the detection precision of intricate and small defects. Evaluation on the NEU-DET dataset reveals that the upgraded model exhibits superior detection accuracy across most of the six defect categories, resulting in an overall mean average precision boost from 76.1 % to 77.6 %. Particularly noteworthy is the substantial enhancement in detecting small and medium-scale defects like Inclusion, Scratches, and Crazing. These findings underscore the efficacy of the C2f_EMA module in augmenting multi-scale feature representation within the YOLOv8 framework, all while preserving its lightweight nature and real-time performance. Consequently, this approach proves to be well-suited for surface defect identification in hot-rolled steel strip production lines.
