Surface Technology (表面技术)•2026•DOI: 10.16490/j.cnki.issn.1001-3660.2026.09.009
Titanium alloys are extensively employed in aerospace, chemical, energy, and biomedical engineering owing to their high specific strength, low density, and excellent corrosion resistance. However, their inherently low surface hardness, poor wear resistance, and high friction coefficient restrict application under high-load, long-life conditions. Nitriding, a thermochemical treatment in which nitrogen atoms diffuse into the surface below the alloy transformation temperature to form a hard nitride layer, serves as an important means to upgrade surface performance. Its effect on fatigue behaviour is twofold: the nitrided layer introduces residual compressive stress and a hardness gradient that suppress crack initiation, while the brittle nitride film, grain coarsening, and interfacial stress concentration created during processing can act as fatigue crack nucleation sites and reduce fatigue life. This review systematically examines the effects of gas nitriding, plasma nitriding, hybrid nitriding, and several novel nitriding techniques on the fatigue response of representative titanium alloys. Conventional gas nitriding and high-temperature plasma nitriding produce a 2–10 µm surface compound layer of brittle TiN and Ti2N with hardness of 1,000–2,000 HV yet very low fracture toughness, which readily develops surface micro-cracks under cyclic loading and serves as the dominant fatigue crack origin. Beneath it, a 20–100 µm thick nitrogen diffusion zone exhibits graded hardness and high residual compression. Low-temperature, short-duration, or energy-controlled processes such as plasma nitriding, low-temperature plasma nitriding, and pulsed laser nitriding tend to form thin compound layers and deep diffusion layers, pushing crack sources to subsurface or internal defects and extending fatigue life. Hybrid treatments (nitriding followed by shot peening or heat treatment) further suppress surface crack initiation by removing the brittle layer, refining grains, and introducing high residual compressive stress, achieving significant fatigue strength improvement. The review clarifies the intrinsic relationship between nitrided layer architecture and fatigue performance, and reveals the micro-mechanisms of fatigue crack initiation and propagation, providing a theoretical basis for optimizing titanium alloy surface treatment processes.
China Foundry•2026•DOI: 10.1007/s41230-026-5163-9
In laser powder bed fusion (LPBF) additive manufacturing, surface depressions caused by melt pool instability can induce defects throughout the layer-by-layer printing process. To address the limited understanding of interlayer defect transmission mechanisms, synchrotron X-ray in situ imaging was used to systematically investigate the dynamic evolution of surface depressions during multi-pass printing by adjusting interlayer process parameters. Experimental results show that insufficient energy input in the first layer leads to balling and fracture of melt tracks. When the energy input in the second layer is increased, local overheating at the gap between melt tracks from the previous layer causes surface depressions. Reducing the energy input in the third layer hinders melt backflow, enlarging the depression region. Further lowering the energy input in the final layer leads to the formation of internal unfused defects. This study reveals the dynamic correlation between surface depressions and interlayer defect evolution, offering critical experimental evidence and theoretical guidance for closed-loop interlayer process control in laser additive manufacturing.
Journal of Central South University•2026•DOI: 10.1007/s11771-025-6070-8
Graphite has the potential to mediate the reduction process of Cr(VI) by oxalic acid (OA), but a reasonable modification is required to enhance the mediation of electron transfer. In this study, biosynthetic Schwertmannite (Sch) modified graphite (Sch@G) was pyrolyzed at 700℃ for Cr(VI) remediation. Biosynthetic Sch particles were successfully loaded on the graphite, providing high specific surface area and abundant O-containing functional groups. The removal efficiency of Cr(VI) reached 90.42% within 60 min, facilitated by the synergistic between 1 g/L Sch@G and 1 mmol/L OA. Additionally, the comparative experiments exhibited a significant capacity of Sch@G in a wide pH range (pH 2−10), the removal efficiency was 97.9% within 60 min even at pH 10. Furthermore, the catalyst presented superior environmental adaptability in solutions containing various types of anions (Cl−, SO4^2−, NO3−, H2PO4−). Mechanism analysis revealed that the catalyst greatly promotes the transfer of electrons from OA to Cr-contaminants, along with the release of low-valent Fe from Sch, enabling efficient electrons transfer to the Cr-contaminant. Meanwhile, the addition of OA could complex OA-Cr(VI) compound, lowering the activity of Cr(VI) and facilitating the subsequent Cr(VI) removal. Generally, the synergistic effect of the catalyst and OA can form an efficient system that enables rapid and effective remediation of Cr(VI) contamination across a wide pH range. Thus, the catalyst presents as a promising graphite-based biomaterial for the rapid and effective remediation of Cr(VI) contaminants from wastewater.
Journal of Central South University•2026•DOI: 10.1007/s11771-025-6108-y
With increasing mining depth in metal mines, the stability of roadway support structures is significantly affected by the complex surrounding rock. This study performs biaxial compression and bolt pull-out experiments on anchorage body specimens with different structural plane dip angles to explore failure mechanisms of anchorage structures and evolutionary law of bolt anchorage force. Results show the dip angle notably impacts the bearing capacity and failure modes of anchorage specimens. Their peak stress exhibits a V-shaped trend: decreasing from 54.80 MPa to 19.65 MPa as dip angles increase from 0° to 45°, with failure mode transitioning from tensile to shear; at 60°, it becomes a tensile-dominated mixed mode. Bolt anchoring significantly enhances bearing capacity (most remarkably by 153.22% at 45°) and changes failure from brittle to ductile. Pull-out tests reveal two failure modes: slip at the bolt-rock interface and bolt fracture. At 45°, bolt fracture occurs under a 14.55 kN peak pull-out load, matching the bolt's yield strength. This failure mechanism involves two key factors: structural plane sliding that shears the bolt, and mechanical interlocking that restricts pull-out, substantially increasing anchorage force. These findings provide insights for stability assessment and support design of roadway structures in complex geological environments.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-025-01753-w
Joint health is critical for musculoskeletal (MSK) conditions that are affecting approximately one-third of the global population. Monitoring of joint torque can offer an important pathway for the evaluation of joint health and guided intervention. However, there is no technology that can provide the precision, effectiveness, low-resource setting, and long-term wearability to simultaneously achieve both rapid and accurate joint torque measurement to enable risk assessment of joint injury and long-term monitoring of joint rehabilitation in wider environments. Herein, we propose a piezoelectric boron nitride nanotubes (BNNTs)-based, AI-enabled wearable device for regular monitoring of joint torque. We first adopted an iterative inverse design to fabricate the wearable materials with a Poisson’s ratio precisely matched to knee biomechanics. A highly sensitive piezoelectric film was constructed based on BNNTs and polydimethylsiloxane and applied to precisely capture the knee motion, while concurrently realizing self-sufficient energy harvesting. With the help of a lightweight on-device artificial neural network, the proposed wearable device was capable of accurately extracting targeted signals from the complex piezoelectric outputs and then effectively mapping these signals to their corresponding physical characteristics, including torque, angle, and loading. A real-time platform was constructed to demonstrate the capability of fine real-time torque estimation. This work offers a relatively low-cost wearable solution for effective, regular joint torque monitoring that can be made accessible to diverse populations in countries and regions with heterogeneous development levels, potentially producing wide-reaching global implications for joint health, MSK conditions, ageing, rehabilitation, personal health, and beyond.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01636-6
The coupling of fast redox kinetics, high-energy density, and prolonged lifespan is a permanent aspiration for aqueous rechargeable zinc batteries, but which has been severely hampered by a narrow voltage range and suboptimal compatibility between the electrolytes and electrodes. Here, we unprecedentedly introduced an electric ambipolar effect for synergistic manipulation on Zn2+ ternary-hydrated eutectic electrolyte (ZTE) enabling high-performance Zn-Br2 batteries. The electric ambipolar effect motivates strong dipole interactions among hydrated perchlorates and bipolar ligands of L-carnitine (L-CN) and sulfamide, which reorganized primary cations solvation sheath in a manner of forming Zn[(L-CN)(SA)(H2O)4]2+ configuration and dynamically restricting desolvated H2O molecules, thus ensuring a broadened electrochemical window of 2.9 V coupled with high ionic conductivity. Noticeably, L-CN affords an electrostatic shielding effect and an in situ construction of organic–inorganic interphase, endowing oriented Zn anode plating/stripping reversibly for over 2400 h. Therefore, with the synergy of electro/nucleophilicity and exceptional compatibility, the ZTE electrolyte dynamically boosts the conversion redox of Zn-Br2 batteries in terms of high specific capacity and stable cycling performance. These findings open a window for designing electrolytes with synergetic chemical stability and compatibility toward advanced zinc-ion batteries.
Transactions of Nonferrous Metals Society of China (中国有色金属学报)•2025•DOI: 10.1016/S1003-6326(25)67014-2
The effects of adding a novel Al−3Ti−4.35La master alloy and Nd and heat treatment on the microstructure and mechanical properties of Al−7Si alloy were investigated. The results showed that the secondary dendrite arm spacing of α-Al in the as-cast Al−7Si alloy was refined from 18.3 to 11.9 μm after modification with 0.2 wt.% Al−Ti−La and 0.03 wt.% Nd, and the length of eutectic Si was reduced from 8.6 to 5.0 μm. After heat treatment at 535 °C for 3 h followed by 165 °C for 3 h, the morphology of the eutectic Si became more rounded, and the size decreased. The microhardness, ultimate tensile strength, and elongation were HV 66.1, 184.9 MPa, and 24.4%, respectively, which increased by 24.2%, 11.6%, and 194.0% compared to the as-cast state. The addition of Al−3Ti−4.35La master alloy and Nd can reduce the nucleation temperature of eutectic Si in Al−7Si, thereby suppressing its growth. Notably, the Ti2(Al,Si)20(La,Nd) phase formed in the Al−7Si alloy after the addition of Al−Ti−La and Nd adhered to or coexisted near the eutectic Si particles, inhibiting their growth.
Transactions of Nonferrous Metals Society of China (中国有色金属学报)•2025•DOI: 10.1016/S1003-6326(25)67022-1
Based on the application requirements for porous dental implants, four porous structures of gyroid, RD (rhombic dodecahedron), cubic, and CHC (three identical cylinders hollow cubic) for porous titanium implants have been designed and fabricated using selective laser melting (SLM) technology. Typically, the unit cell dimensions range from 0.5 to 1.6 mm, with pore diameters between 300 and 900 µm, achieving porosities of 60%−80%. The influence of porous structures with small unit cell on scaffold formability and mechanical properties was investigated through compression, torsion tests as well as finite element simulations. Consequently, gyroid scaffolds exhibit optimal formability with the lowest porosity and pore deviation. With the same porosity, gyroid and RD scaffolds exhibit lower compressive strength than cubic and CHC scaffolds, yet their torsional properties show an inverse relationship. Moreover, gyroid scaffolds possess the highest torque but the lowest compressive strength and elastic modulus. The gyroid scaffold with 60% porosity shows a modulus of 3.96 GPa, matching bone modulus of 0−30 GPa. Its compressive strength reaches 176.3 MPa, exceeding that of bone by 100 MPa. Additionally, the torque for the d4.0 mm implant is 2.22 N·m, approaching the FDA safe torque of 2.3 N·m. Therefore, the gyroid represents the most ideal structure for porous dental implants.
Journal of Semiconductors (半导体学报 - 中国科学院半导体研究所)•2025•DOI: 10.1088/1674-4926/25030012
In recent years, research advancements have highlighted the critical role of the A-site cation in determining the optoelectronic and physicochemical properties of organic–inorganic lead halide perovskites. Mixed-cation perovskites (MCPs) have been extensively used as absorber thin films in perovskite solar cells (PSCs), achieving high power conversion efficiencies (PCE) over 26%. The incorporation of mixed cations has led to a more optimal tolerance factor for the crystal structure, enhancing structural stability and providing additional functionalities to improve the chemical stability of the absorber thin films. However, mixed-cation perovskite absorbers often experience element and phase segregation, which can reduce device efficiency and operational lifespan. This segregation is a widespread phenomenon observed across various types of MCPs, whether in 2D or 3D structures. Therefore, understanding the fundamental causes of non-uniformity and phase segregation, as well as effective nanoscale regulatory strategies, is essential for enhancing the performance of PSCs. The development of high-quality MCPs with highly uniform cation distribution and stable phases is critical for addressing the stability challenges in PSCs.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.04.006
To reveal the deterioration mechanism of coal-rock assemblages under chemical corrosion and dynamic loading, chemical corrosion and dynamic impact experiments were conducted. Under different chemical corrosion conditions, the weakening characteristics, observable characteristics, softening characteristics of the dynamic parameters, dynamic failure characteristics, dynamic failure forms and dynamic microscopic characteristics were analyzed. Under each corrosion condition, the dynamic elastic modulus, dynamic deformation modulus and dynamic peak intensity tended to decrease with immersing time. The dynamic elastic modulus, dynamic deformation modulus and dynamic peak intensity exhibited an inverted U-shaped trend. Under dynamic impact, the failure process of acidly corroded samples can be divided into the following stages: the initial stage, elastic energy accumulation stage, local failure of coal and secondary rock crack expansion stage, coal fragment ejection stage, rock spalling stage and complete instability stage. Under dynamic impact, failure modes exist: coal crushing failure, rock fragmenting failure, rock splitting failure and full splitting failure. After impact failure, sample fragments are distributed in powder, granular, cone and block forms. Based on Zhu-Wang-Tang nonlinear viscoelastic properties, a model considering chemical corrosion and impact damage was proposed. The combined effects of chemical and impact-induced damage on the dynamic mechanical properties of coal-rock assemblages were systematically analyzed.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.06.004
In recent years, computational chemistry studies of chalcopyrite and pyrite flotation surfaces have advanced significantly, yet current methods are constrained by small system sizes and inadequate consideration of hydration and temperature effects, limiting their ability to replicate real flotation environments. In this study, we employed the self-consistent charge density functional tight-binding (SCC-DFTB) parameterization method to develop a parameter set, CuFeOrg, encompassing interactions among Cu, Fe, C, H, O, N, S, P, and Zn elements, to investigate surface interactions in large-scale flotation systems of chalcopyrite and pyrite. Validation through bulk modulus, atomic displacement, band structure, surface relaxation, surface Mulliken charge distribution, and adsorption tests of typical flotation reagents on mineral surfaces demonstrated that CuFeOrg achieves DFT-level accuracy while significantly outperforming DFT in computational efficiency. By constructing large-scale hydration systems of mineral surfaces, as well as systems incorporating combined mineral surface, flotation reagent, and hydration interactions, we more realistically reproduced actual flotation environments. Dynamic analysis results were consistent with mineral surface contact angle experiments. CuFeOrg lays the foundation for future studies of more complex and diverse chalcopyrite and pyrite flotation surface systems.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.07.006
Coal mine underground reservoir (CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams. This study develops a novel framework of steeply inclined coal mine underground reservoirs (SICMUR), which is a paradigm shift from conventional CMUR that the coal seam itself serves as the reservoir floor, challenging conventional designs due to depth-dependent permeability and mechanical constraints. Triaxial mechanical-seepage tests on Xinjiang Wudong coal samples (100, 200, 300 m depths) revealed a 3.5 MPa triaxial strength increase per 100 m depth and a 58-fold post-peak permeability surge at 300 versus 100 m. Similar model simulations revealed mining-induced stress redistribution and significant deformation effects, particularly subsidence and water-conducting fractures during lower coal seam mining. Results indicate a minimum 40 m safety distance between reservoirs and lower coal seams. Critical construction parameters were investigated for Wudong mine SICMUR as collapse zone heights (9.9–12.31 m) and water-conducting fracture zone heights (31.96–37.40 m). This work systematically bridges SICMUR concepts to field implementation, offering a framework for water preservation in steeply inclined mining while addressing safety concerns, providing a new approach for water reservation in steeply inclined coal mining.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.09.008
To investigate the influence of non-uniform water distribution on the mechanical properties and failure behavior of red sandstone, we designed five immersion heights and durations to achieve varying non-uniform water distribution states. Uniaxial compression tests were conducted on red sandstone under these conditions. The effects of non-uniform water distribution on deformation, failure, strength, and energy characteristics of red sandstone were analyzed. The impact of non-uniform water distribution on the intensity of rock failure was discussed, and the failure mechanism under non-uniform water distribution was revealed. The hazards of low immersion heights on underground rock structures were analyzed. The results demonstrate that peak strength and elastic modulus of red sandstone exhibit high sensitivity to immersion height, with reductions of 38% and 23% respectively even at L=1/50H. Water immersion reduces both energy storage capacity and energy dissipation capability of red sandstone. The immersion height and duration influence the failure mode of red sandstone by controlling the migration and separation of dry-wet interfaces. Low immersion height poses significant risks to underground rock structures (e.g., a 38% strength reduction when L=1/50H), and the concentration degree of water non-uniform distribution is the key factor in assessing the weakening effect of water on rocks.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.10.011
To investigate groundwater influence on stability and rockburst mechanism of deep hard-rock rectangular tunnels, water-immersed treatment and uniaxial compressive acoustic emission (AE) experiments were conducted on rectangular tunnel specimens. Energy dissipation characteristics, AE evolution characteristics and damage evolution characteristics of rectangular tunnels were analysed under water-immersed condition. Under water-immersed condition, tunnel specimens were quite sensitive to water. Average peak stress and average peak strain energy exhibited negative exponential decay with water-immersed time. Among them, after 12 d of water immersion, average peak stress of specimens decreased by 28%. Average total strain energy decreased by 70%. Average elastic strain energy decreased by 71% and average dissipated strain energy decreased by 68%. After 62 d of water immersion, average peak stress of specimens decreased by 34%. Average total strain energy decreased by 78%. Average elastic strain energy decreased by 79% and average dissipated strain energy decreased by 75%. Water weakened bonding among mineral particles. Moreover, it undermined load-bearing capacity and diminished energy-storage properties. Under high stress, massive releasable elastic strain energy stored in natural specimens within pre-peak stage may abruptly release after peak stress. This caused rapid crack development and connection in specimens. During accumulation and release of elastic strain energy, initial failure typically occurred at sidewalls. This failure location was not affected by water. Compared with natural specimens, specimens immersed in water for 62 d had the lowest peak values of cumulative amplitude, cumulative AE energy and cumulative AE count. After 62 d of water immersion, peak values of cumulative amplitude, cumulative AE energy and cumulative AE count of specimens decreased by 84%, 97% and 99%. Compared with AE damage model, fitting degree of energy damage model was higher. For natural specimens, fitting degree of energy damage model was 0.96. For specimens immersed in water for 12 d, fitting degree of energy damage model was 0.96. For specimens immersed in water for 62 d, fitting degree of energy damage model was 0.72. Therefore, an energy damage model had more remarkable applicability and reliability. By establishing dynamic mapping relationship between energy and damage in the model, accuracy of rockburst early warning has been significantly improved. This provided scientific basis for support structure design of rectangular tunnels and regulation of high strain energy.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.10.002
Retrogressive landslides in sensitive clays pose significant risks to nearby infrastructure, as natural toe erosion or localized disturbances can trigger progressive block failures. While prior studies have largely relied on two-dimensional (2D) large-deformation analyses, such models overlook key three-dimensional (3D) failure mechanisms and variability effects. This study develops a 3D probabilistic framework by integrating the Coupled Eulerian–Lagrangian (CEL) method with random field theory to simulate retrogressive landslides in spatially variable clay. Using Monte Carlo simulations, we compare 2D and 3D random large-deformation models to evaluate failure modes, runout distances, sliding velocities, and influence zones. The 3D analyses captured more complex failure modes—such as lateral retrogression and asynchronous block mobilization across slope width. Additionally, the 3D analyses predict longer mean runout distances (13.76 vs. 11.92 m), wider mean influence distance (11.35 vs. 8.73 m), and higher mean sliding velocities (4.66 vs. 3.94 m/s) than their 2D counterparts. Moreover, 3D models exhibit lower coefficients of variation (e.g., 0.10 for runout distance) due to spatial averaging across slope width. Probabilistic hazard assessment shows that 2D models significantly underpredict near-field failure probabilities (e.g., 48.8% vs. 89.9% at 12 m from the slope toe). These findings highlight the limitations of 2D analyses and the importance of multi-directional spatial variability for robust geohazard assessments. The proposed 3D framework enables more realistic prediction of landslide mobility and supports the design of safer, risk-informed infrastructure.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.12.008
Microseismic (MS) monitoring is an effective technique to detect mining-induced rock fractures. However, recognizing grouting-induced signals is challenging due to complex geological conditions in deep rock plates. Therefore, a hybrid model (WM-ResNet50) integrating data enhancement, a deep convolutional neural network (CNN), and convolutional block attention modules (CBAM) was proposed. Firstly, an MS system was established at the Xieqiao coal mine in Anhui Province, China. MS waveforms and injection parameters were acquired during grouting. Secondly, signals were categorized based on time–frequency characteristics to build a dataset, which was divided into training, validation, and test sets at a ratio of 4:1:1. Subsequently, the performance of WM-ResNet50 was evaluated based on indices such as individual precision, total accuracy, recall, and loss function. The results indicated that WM-ResNet50 achieved an average recognition accuracy of 94.38%, surpassing that of a simple CNN (90.04%), ResNet18 (91.72%), and ResNet50 (92.48%). Finally, WM-ResNet50 was applied to monitor the whole process at laboratory tests and field cases. Both results affirmed the feasibility and effectiveness of MS inversion in predicting actual slurry diffusion ranges within deep rock layers. By comparison, it was revealed that the MS sources classified by WM-ResNet50 matched grouting records well. A solution to address insufficient diffusion under long-borehole grouting has been proposed. WM-ResNet50's accuracy was validated through in-situ coring and XRD analysis for cement-based hydration products. This study provides a beneficial reference for similar rock signal processing and in-field grouting practices.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-2971-z
The equilibrium phase relations of the CaO–SiO2–TiO2–5wt%Fe3O4 system were experimentally investigated at 1400°C in air. High-temperature equilibration-quenching techniques were employed in an electric MoSi2 resistance heated furnace, with phase composition analysis conducted using an electron probe microanalyzer and X-ray diffraction. A single liquid region, liquid–solid phase equilibria regions (including liquid–tridymite, liquid–rutile, liquid–perovskite, and liquid–wollastonite), and three-phase equilibria regions of liquid–tridymite–rutile and liquid–rutile–perovskite were found. The 1400°C isothermal sections of the CaO–SiO2–TiO2–5wt%Fe3O4 system in air were projected. The present experimental results exhibited good agreement with the calculation results obtained from FactSage.
Chinese Journal of Mechanical Engineering•2025•DOI: 10.1186/s10033-025-01350-3
The fused quartz hemispherical resonator is the core component of the hemispherical resonator gyroscope. It features a complex shape and is made from a material that is difficult to process. Scratches are easily introduced during grinding, potentially degrading the mass-stiffness-damping symmetry; however, the underlying mechanisms of this influence have not been fully understood. This paper aims to investigate the effects of scratch defects on the frequency splitting and quality factor of the hemispherical resonator. First, finite element models of the hemispherical resonator with scratches are established. Then, the effects of the mass-stiffness factor, as well as the latitude and length of the scratches, on frequency splitting are analyzed. Furthermore, the impacts of latitude, length, and the first four harmonics of the unbalanced mass caused by scratches on thermoelastic damping and anchor loss are examined. Simulation results indicate that scratches above 55° latitude cause frequency splitting solely due to stiffness changes. Frequency splitting caused by scratches of the same size on the inherent rigidity shaft at the rim is approximately 50% of that near the transition fillet. Frequency splitting varies linearly with the volume of material removed by scratches. Scratches have little effect on thermoelastic damping. The first three harmonics of the unbalanced mass due to scratches at the rim are the primary contributors to anchor loss. Finally, focused ion beam trimming experiments are conducted at different locations on the hemispherical resonator. The trends observed in the experimental results are consistent with the simulation results. This work provides guidance for evaluating the impact of scratches on the performance of hemispherical resonators and for developing appropriate trimming processes.
Chinese Journal of Mechanical Engineering•2025•DOI: 10.1186/s10033-025-01273-z
As a crucial component of intelligent chassis systems, air suspension significantly enhances driver comfort and vehicle stability. To further improve the adaptability of commercial vehicles to complex and variable road conditions, this paper proposes a linear motor active suspension with quasi-zero stiffness (QZS) air spring system. Firstly, a dynamic model of the linear motor active suspension with QZS air spring system is established. Secondly, considering the random uncertainties in the linear motor parameters due to manufacturing and environmental factors, a dynamic model and state equations incorporating these uncertainties are constructed using the polynomial chaos expansion (PCE) method. Then, based on H2 robust control theory and the Kalman filter, a state feedback control law is derived, accounting for the random parameter uncertainties. Finally, simulation and hardware-in-the-loop (HIL) experimental results demonstrate that the PCE-H2 robust controller not only provides better performance in terms of vehicle ride comfort compared to general H2 robust controller but also exhibits higher robustness to the effects of random uncertain parameters, resulting in more stable control performance.
Chinese Journal of Mechanical Engineering•2025•DOI: 10.1186/s10033-025-01217-7
The high-temperature oxidation resistance of AISI 321 stainless steel used in solar thermal power heat exchangers determines its service life. In this study, aluminizing and subsequent laser shock peening (LSP) treatments were employed to improve the high-temperature oxidation resistance of AISI 321 stainless steel at 620 °C. These two treatments decreased the oxidation rate of AISI 321 steel. Specifically, the optimal oxidation resistance was observed in aluminized steel before oxidation for 144 h owing to the increased entropy of the LSP-treated specimen. After 144 h, LSP-treated steel achieved the best oxidation resistance because of the formation of a protective α-Al2O3 film. Moreover, the large amount of subgrain boundaries formed on the aluminized layer of the LSP-treated samples could act as short-circuit paths for the outward diffusion of Al, facilitating the rapid nucleation of α-Al2O3. Meanwhile, the aluminized layer could isolate the contact between the oxidation environment and matrix, thereby decreasing the oxidation rate. Furthermore, the minimum oxidation parabolic constant was calculated for LSP-treated steel (6.45787 × 10−14), which was 69.18% and 36.36% that of aluminized and 321 steel, respectively, during the entire oxidation process. Therefore, the combination of aluminizing and LSP treatments can improve the high-temperature oxidation resistance of 321 stainless steel, providing a new idea for its surface treatment to achieve a long service life at high temperatures.
Chinese Journal of Mechanical Engineering•2025•DOI: 10.1186/s10033-024-01172-9
Tracking control of tendon-driven manipulators has become a prevalent research area. However, the existence of flexible elastic tendons generates substantial residual vibrations, resulting in difficulties for trajectory tracking control of the manipulator. This paper proposes the radial basis function neural network adaptive hierarchical sliding mode control (RBFNNA-HSMC) method, which combines the dynamic model of the elastic tendon-driven manipulator (ETDM) with radial basis neural network adaptive control and hierarchical sliding mode control technology. The aim is to achieve trajectory tracking control of ETDM even under conditions of model inaccuracy and disturbance. The Lyapunov stability theory demonstrates the stability of the proposed RBFNNA-HSM controller. In order to assess the effectiveness and adaptability of the proposed control method, simulations and experiments were performed on a two-DOF ETDM. The RBFNNA-HSM method shows superior tracking accuracy compared to traditional model-based HSM control. The experiment shows that the maximum tracking error for ETDM double-joint trajectory tracking is below 2.593×10-3 rad and 1.624×10-3 rad, respectively.
Journal of Central South University•2025•DOI: 10.1007/s11771-025-6137-6
Aerodynamic drag is the dominant factor contributing to energy consumption as the operational speed of high-speed trains increases, necessitating effective aerodynamic optimization strategies. This study investigates the aerodynamic characteristics of the bogie region under two bogie fairing configurations: baseline bogie fairing (BBF) and full bogie fairing (FBF). Both stationary and rotating wheelset conditions are considered. Wind tunnel experiments were conducted on a full-scale bogie model equipped with a wheelset drive system to simulate wheelset rotation. Additionally, numerical simulations were employed to analyze flow structures. Results indicate that the FBF configuration promotes a more uniform front-to-rear pressure distribution in the bogie region. The rotation of the wheelset notably affects the airflow near the wheels and extends its influence throughout the entire bogie region. Specifically, wheelset rotation reduces drag by 6.38% in the BBF configuration but increases drag by 3.5% in the FBF configuration. Further analysis reveals that, in the FBF configuration, aerodynamic drag primarily originates from the wheelsets. The rotating wheelset increases the aerodynamic drag by 18.8% for the rear wheelset, which is attributed to the shift in the pressure curve on the wheelset in the rotating direction. Therefore, the impact of wheelset rotation on aerodynamic characteristics should not be overlooked.
Journal of Central South University•2025•DOI: 10.1007/s11771-025-6121-1
Additive manufacturing (AM) of SiCP/Al composites has shown significant potential for expanding the application of aluminum matrix composites (AMCs) due to their outstanding mechanical properties and wear performance. However, conventional mechanically mixed powders for AM are limited due to the possible powder agglomeration and poor fluidity. In this study, the spherical SiCP/AlSi10Mg composite powders prepared by spray granulation were employed to fabricate SiCP-reinforced AlSi10Mg composites using laser powder bed fusion (LPBF). The impacts of laser power on microstructure evolution and wear properties of composites were systematically investigated. The results indicated that an in-situ reaction between the aluminum matrix and SiCP during the LPBF process, resulted in the formation of particle-like and strip-like strengthening phase Al4SiC4. By adjusting the laser power (from 270 W to 350 W) to change the ratio of SiCP to Al4SiC4, micro-defects could be effectively limited, and wear performance could be improved. Consequently, with an optimized ratio of SiCP to Al4SiC4, the composite exhibited a mixed strengthening mechanism caused by the SiCP and Al4SiC4 reinforcing phases. At a laser power of 310 W, the sample exhibited minimal porosity with a microhardness value reaching 265.38HV, while maintaining relatively low average friction coefficient and wear rate. In addition, compared with other studies, the hardness obtained was superior to that of the AlSi10Mg and other reported SiCP/AlSi10Mg composites with similar volume fractions using the mixed powders.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-025-3201-z
The performance of the fuel electrode in a solid oxide electrolysis cell (SOEC) is crucial to facilitating fuel gas electrolysis and is the key determinant of overall electrolysis efficiency. Nevertheless, the commercialization of integrated CO2–H2O electrolysis in SOEC remains constrained by suboptimal catalytic efficiency and long-term stability limitations inherent to conventional fuel electrode architectures. A novel high-entropy Sr2FeTi0.2Cr0.2Mn0.2Mo0.2Co0.2O6−δ (SFTCMMC) was proposed as a prospective electrode material of co-electrolysis in this work. The physicochemical properties and electrochemical performance in the co-electrolysis reaction were investigated. Full cell is capable of electrolyzing H2O and CO2 effectively with an applied voltage. The effects of temperature, H2O and CO2 concentrations, and applied voltage on the electrochemical performance of Sc0.18Zr0.82O2−δ (SSZ)-electrolyte supported SOEC were investigated by varying the operating conditions. The SOEC obtains a favorable electrolysis current density of 1.47 A·cm−2 under co-electrolysis condition at 850°C with 1.5 V. Furthermore, the cell maintains stable performance for 150 h at 1.3 V, and throughout this period, no carbon deposition is detected. The promising findings suggest that the high-entropy SFTCMMC perovskite is a viable fuel electrode candidate for efficient H2O/CO2 co-electrolysis.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-2977-6
Large-scale underground projects need accurate in-situ stress information, and the acoustic emission (AE) Kaiser effect method currently offers lower costs and streamlined procedures. In this method, the accuracy and speed of Kaiser point identification are important. Thus, this study aims to integrate chaos theory and machine learning for accurately and quickly identifying Kaiser points. An intelligent model of the identification of AE partitioned areas was established by phase space reconstruction (PSR), genetic algorithm (GA), and support vector machine (SVM). Then, the plots of model classification results were made to identify Kaiser points. We refer to this method of identifying Kaiser points as the partitioning plot method based on PSR–GA–SVM (PPPGS). The PSR–GA–SVM model demonstrated outstanding performance, which achieved a 94.37% accuracy rate on the test set, with other evaluation metrics also indicating exceptional performance. The PPPGS identified Kaiser points similar to the tangent-intersection method with greater accuracy. Furthermore, in the feature importance score of the classification model, the fractal dimension extracted by PSR ranked second after accumulated AE count, which confirmed its importance and reliability as a classification feature. The PPPGS was applied to in-situ stress measurement at a phosphate mine in Guizhou Weng’an, China, to validate its practicability, where it demonstrated good performance.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01564-5
Formamidinium lead bromide (FAPbBr3) perovskite nanocrystals (NCs) are promising for display and lighting due to their ultra-pure green emission. However, the thermal quenching will exacerbate their performance degradation in practical applications, which is a common issue for halide perovskites. Here, we reported the heat-resistant FAPbBr3 NCs prepared by a ligand-engineered room-temperature synthesis strategy. An aromatic amine, specifically β-phenylethylamine (PEA) or 3-fluorophenylethylamine (3-F-PEA), was incorporated as the short-chain ligand to expedite the crystallization rate and control the size distribution of FAPbBr3 NCs. Employing this ligand engineering approach, we synthesized high quality FAPbBr3 NCs with uniform grain size and reduced long-chain alkyl ligands, resulting in substantially suppressed thermal quenching and enhanced carrier transportation in the perovskite NCs films. Most notably, more than 90% of the room temperature PL intensity in the 3-F-PEA modified FAPbBr3 NCs film was preserved at 380 K. Consequently, we fabricated ultra-pure green EL devices with a room temperature external quantum efficiency (EQE) as high as 21.9% at the luminance of above 1,000 cd m−2, and demonstrated less than 10% loss in EQE at 343 K. This study introduces a novel room temperature method to synthesize efficient FAPbBr3 NCs with exceptional thermal stability, paving the way for advanced optoelectronic device applications.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01539-6
Monitoring minuscule mechanical signals, both in magnitude and direction, is imperative in many application scenarios, e.g., structural health monitoring and robotic sensing systems. However, the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix, and achieving sensitivity for detecting micrometer-scale deformations is also challenging. Herein, we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement, capable of detecting minute anisotropic deformations. The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%, thereby enabling its utility in accurately discerning the 5 μm-height wrinkles in thin films and in monitoring human pulse waves. The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase. Additionally, when integrated with machine learning techniques, the sensor's capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100% accuracy. The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli, offering a novel perspective for enhancing recognition accuracy.