Search Results (2,730)

Tungsten and tungsten alloys are widely used in important industrial fields due to their high density, hardness, melting point, and corrosion resistance. However, machining often leaves processing marks on their surface, significantly affecting the surface quality of precision components in industrial applications. Electrolytic polishing offers high efficiency, low workpiece wear, and simple processing. In this study, an electrolytic polishing method is adopted and a novel trisodium phosphate–sodium hydroxide electrolytic polishing electrolyte is developed to study the effects of temperature, voltage, polishing time, and solution composition on the surface roughness of a tungsten–nickel–iron alloy. The optimal voltage, temperature, and polishing time are determined to be 15 V, 55 °C, and 35 s, respectively, when the concentrations of trisodium phosphate and sodium hydroxide are 100 g·L⁻¹ and 6 g·L⁻¹. In addition, glycerol is introduced into the electrolyte as an additive. The calculated LUMO value of glycerol is −5.90 eV and the HOMO value is 0.40 eV. Moreover, electron enrichment in the hydroxyl region of glycerol can form an adsorption layer on the surface of the tungsten alloy, inhibit the formation of micro-pits, balance ion diffusion, and thus promote the formation of a smooth surface. At 100 mL·L⁻¹ of glycerol, the roughness of the tungsten–nickel–iron alloy decreases significantly from 1.134 μm to 0.582 μm. The electrochemical polishing mechanism of the tungsten alloy in a trisodium phosphate electrolyte is further investigated and explained according to viscous film theory. This study demonstrates that the trisodium phosphate–sodium hydroxide–glycerol electrolyte is suitable for electropolishing tungsten–nickel–iron alloys. Overall, the results support the application of tungsten–nickel–iron alloy in the electronics, medical, and atomic energy industries. Full article

To address the limitations of single-layer nitride coatings, such as poor load adaptability and low long-term durability, MoN/TiN multilayer coatings were prepared via high-power impulse magnetron sputtering (HiPIMS). HiPIMS produces highly ionized plasmas that enable intense ion bombardment, yielding nitride films with enhanced mechanical strength, durability, and thermal stability versus conventional methods. The multilayer coating demonstrated a low coefficient of friction (COF, ~0.4) and wear rate (1.31 × 10⁻⁷ mm³/[N·m]). In contrast, both TiN and MoN coatings failed at 5 N and 10 N loads, respectively. Under increasing loads, the multilayer coating maintained stable wear rates (1.84–3.06 × 10⁻⁷ mm³/[N·m]) below 20 N, and ultimately failed at 25 N. Furthermore, the MoN layer contributes to COF reduction. Grazing-incidence X-ray diffraction analysis confirmed the enhanced crystallographic stability of the multilayer coating, thereby revealing a dominant (111) orientation. The multilayer architecture suppresses crack propagation while effectively balancing hardness and toughness, offering a promising design for extreme-load applications. Full article

This study investigates the microstructural evolution, mechanical behavior, and electrochemical performance of CoCrFeNiNb and CoCrFeNiV HEAs fabricated via mechanical alloying and spark plasma sintering. Microstructural analyses reveal that the alloys have a face-centered cubic (FCC) matrix with Nb-enriched Laves and V-enriched σ phases. The CoCrFeNiNb HEA exhibits superior compressive strength and hardness than CoCrFeNiV due to uniform Laves phases distribution. Fracture surface analysis reveals that at lower sintering temperatures, the fracture is primarily caused by incomplete particle bonding, whereas at higher temperatures, brittle fracture modes dominated via transgranular cracking become predominant. The research results of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) show that both alloys exhibited superior electrochemical stability in a 3.5 wt.% NaCl solution compared to the CoCrFeNi base alloy. X-ray photoelectron spectroscopy (XPS) analysis confirms the formation of stable oxide layers (Nb₂O₅ and V₂O₃) on the precipitated phases, acting as protective barriers against chloride ion penetration. The selective oxidation of Nb and V improves the integrity of the passive film, reducing the corrosion rates and enhancing the long-term durability. These findings highlight the critical role of precipitated phases in enhancing the corrosion resistance of HEAs, and emphasize their potential for use in extreme environments. Full article

Plow loosening machines are essential agricultural machinery in the agricultural production process. Improving the surface strengthening process and extending the working life of the plow teeth of the plow loosening machine are of great significance. In this paper, the preparation of Stellite6/Cu composite coating on the surface of 316L steel substrate intended for strengthening the plow teeth of a plow loosening machine using laser cladding technology was studied. The influence of different laser process parameters on the microstructure and properties of Stellite6/Cu composite coating was investigated. The composite coating powder was composed of Stellite6 powder with a different weight percent of copper. Microstructural analysis, phase composition, elemental distribution, microhardness, wear resistance, and corrosion resistance of the composite coatings on the plow teeth were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness testing, energy dispersive spectroscopy (EDS), friction and wear testing, and electrochemical workstation measurements. The results showed that (1) When the laser power was 1000 W, the average hardness of the prepared Stellite6/Cu composite layer achieved the highest hardness, approximately 1.36 times higher than the average hardness of the substrate, and the composite coating prepared exhibited the best wear resistance; (2) When the scanning speed was 800 mm/min, the composite coating exhibited the lowest average friction coefficient and the optimal corrosion resistance in a 3.5% wt.% NaCl solution with a self-corrosion current density of −7.55 µA/cm²; (3) When the copper content was 1 wt.%, the composite coating achieved the highest average hardness with 515.2 HV, the lowest average friction coefficient with 0.424, and the best corrosion resistance with a current density of −8.878 µA/cm². Full article

In recent years, 3D pixel sensors have been a topic of increasing interest within the High Energy Physics community. Due to their inherent radiation hardness, demonstrated up to a fluence of $3\times {10}^{16}$ 1 MeV equivalent neutrons per square centimeter, 3D pixel sensors have been used to equip the innermost tracking layers of the ATLAS and CMS detector upgrades at the High-Luminosity Large Hadron Collider. Additionally, the next generation of vertex detectors calls for precise measurement of charged particle timing at the pixel level. Owing to their fast response times, 3D sensors present themselves as a viable technology for these challenging applications. Nevertheless, both radiation hardness and fast timing require 3D sensors to be operated with high bias voltages on the order of ∼150 V and beyond. Special attention should therefore be devoted to avoiding problems that could cause premature electrical breakdown, which could limit sensor performance. In this paper, TCAD simulations are used to gain deep insight into the impact of surface isolation layers (i.e., p-stop and p-spray) used by different vendors on the high-voltage tolerance of small-pitch 3D sensors. Results relevant to different geometrical configurations and irradiation scenarios are presented. The advantages and disadvantages of the available technologies are discussed, offering guidance for design optimization. Experimentalmeasurements from existing samples based on both isolation techniques show good agreement with simulated breakdown voltages, thereby validating the simulation approach. Full article

The impact of modulation periods on the microstructure, as well as the tribological and mechanical characteristics of the AlCrTiVNbN/TiSiN nano multilayer films, was investigated. The films were prepared with modulation periods ranging from 4 nm to 7 nm, and their properties were explored using X-ray diffraction (XRD), scanning electron microscope (SEM), nanoindentation, and a tribological tester. All nano multilayer films revealed a face-centered cubic (FCC) structure with a preferred planar direction of (200). As the modulation period increased, the XRD peak moved to higher angles, and the interplanar distance decreased. Also, the mechanical properties deteriorated, and the COF rose monotonically as a result. The nano multilayer film with a modulation period equal to 4 nm exhibited a smooth surface with minimal small particles, the highest hardness of 15.51 ± 0.16 GPa and elastic modulus of 182.89 ± 2.38 GPa, the highest values for the ratios of H/E and H³/E², the lowest average friction coefficient of 0.73, and a wear rate equal to (8.2 9 ± 0.18) × 10⁻⁸ mm³·N⁻¹·m⁻¹. The improvement in the properties of the film was ascribed to the coherent growth and alternating stress field between the AlCrTiVNbN and TiSiN layers. Full article

Oscillatory neural networks have so far been successfully applied to a number of computing problems, such as associative memories, or to handle computationally hard tasks. In this paper, we show how to use oscillators to process time-dependent waveforms with minimal or no preprocessing. Since preprocessing and first-layer processing are often the most power-hungry steps in neural networks, our findings may open new doors to simple and power-efficient edge-AI devices. Full article

Taking the shield construction of Xiamen Metro Line 2 tunnel side-crossing the Tianzhushan overpass and under-crossing the Shen-Hai Expressway as the engineering background, FLAC3D 6.0 software was used to examine the deformation of adjacent structures based on shield construction parameters in upper-soft and lower-hard strata. The reliability of the numerical simulation results was verified by comparing measured and predicted deformations. The study results indicate that deformation of the pile will occur during the construction of the tunnel shield next to the pile foundation. The shape of the pile deformation curve in the horizontal direction is significantly influenced by the distance from the pile foundation to the adjacent tunnel’s centerline, as well as by soil bin pressure, grouting layer thickness, and stress release coefficient. During the tunnel shield construction beneath the expressway, increasing the soil bin pressure, the grouting layer thickness, and reducing the stress release coefficient can effectively minimize surface deformation and differential settlement on both sides of the deformation joints between the bridge and the roadbed. The practice shows that, by optimizing shield construction parameters in upper-soft and lower-hard strata, the deformation of nearby bridges and pavements can be kept within allowable limits. This is significant for reducing construction time and costs. The findings offer useful references for similar projects. Full article

Rock slopes exhibiting anti-inclined interbedded strata have widespread distribution and complex deformation mechanisms. In this study, we used a physical model test with basal friction to replicate the evolution process of the slope deformation. Digital Image Correlation (DIC) and Particle Image Velocimetry (PIV) methods were used to capture the variation in slope velocity and displacement fields. The results show that the slope deformation is conducted by bending of soft rock layers and accumulated overturning of hard blocks along numerous cross joints. As the faces of the rock columns come back into contact, the motion of the slope can progressively stabilize. Destruction of the toe blocks triggers the formation of the landslides within the toppling zone. The toppling fracture zones form by tracing tensile fractures within soft rocks and cross joints within hard rocks, ultimately transforming into a failure surface which is located above the hinge surface of the toppling motion. The evolution of the slope deformation mainly undergoes four stages: the initial shearing, the free rotation, the creep, and the progressive failure stages. Full article

Limited hardness and corrosion resistance restrict 7050 aluminum alloys in aggressive environments. Cr coatings, applied as single layers or over Ti, Al, or Ni buffer layers, were deposited onto 7050 aluminum alloy by direct-current magnetron sputtering; their microstructure, adhesion, mechanical properties, and corrosion behavior were examined. The results indicate that introducing a buffer layer significantly enhances the bonding strength between a Cr coating and an aluminum alloy substrate, with the Ni buffer layer exhibiting the highest bonding strength, nearly three times that of the Cr coating alone. Furthermore, the buffer layer influences the mechanical properties of the Cr coatings, with Ni/Cr and Al/Cr coatings demonstrating increased hardness and elastic modulus. The Ni/Cr coating achieved the highest values of 3.95 GPa and 62.09 GPa, respectively. Regarding corrosion performance, The Cr coatings containing buffer layers showed markedly better corrosion resistance than the bare 7050 Al alloy. A compact Cr₂O₃ passive film formed on their surfaces, cutting the corrosion current density by roughly two orders of magnitude. Among all samples, the Ti/Cr coating performed best, registering the lowest current density (1.687 × 10⁻⁶ A cm⁻²) and the highest charge-transfer resistance (6090 Ω cm²). Full article

Under the global initiative for automotive lightweighting to address climate challenges, this study investigates the microstructure evolution of steel–aluminum composites processed by hot equal-channel angular pressing (H-ECAP). Using 6061-T6 aluminum cores clad with 20 # low carbon steel tubes processed through 1–4 C-path passes (Φ = 120°, ψ = 30°), we demonstrate significant microstructural improvements. The steel component showed progressive grain refinement from 2.2 μm (1 pass) to 1.3 μm (4 pass), with substructures decreasing from 72.19% to 35.46%, HAGB increasing from 31.2% to 34.6%, and hardness increasing from 222 HV to 271 HV. Concurrently, aluminum experienced grain refinement from 59.3 μm to 28.2 μm, with recrystallized structures surging from 0.97% to 71.81%, HAGB increasing from 9.96% to 63.76%, and hardness increasing from 51.4 HV to 83.6 HV. The interfacial layer thickness reduced by 74% (29.98 μm to 7.78 μm) with decreasing oxygen content, containing FeAl₃, Fe₂Al₅, and minimal matrix oxides. Yield strength gradually increased from 361 MPa (one pass) to 372.35 MPa (four passes), accompanied by a significant enhancement in compressive strength. These findings reveal that H-ECAP’s thermomechanical coupling effect effectively enhances interface bonding quality while suppressing detrimental intermetallic growth, providing a viable solution to overcome traditional manufacturing limitations in steel–aluminum composite applications for sustainable mobility. Full article

Hydrogenated amorphous carbon (a-C:H) films are widely valued for their excellent mechanical strength and low friction, but their performance significantly degrades at elevated temperatures, limiting practical applications in aerospace environments. In this work, we aimed to enhance the high-temperature tribological behavior of a-C:H films through controlled silicon (Si) doping. A series of a-C:H:Si films with varying Si contents were fabricated via direct current magnetron sputtering, and their microstructure, mechanical properties, and friction behavior were systematically evaluated from room temperature up to 400 °C. Results show that moderate Si doping (8.3 at.%) substantially enhances hardness and wear resistance, while enabling ultralow friction (as low as 0.0034) at 400 °C. This superior performance is attributed to the synergistic effects of transfer layer formation, preferential Si oxidation, and tribo-induced graphitization. This study provides new insights into the high-temperature lubrication mechanisms of Si-doped a-C:H films and demonstrates the critical role of Si content optimization, highlighting a viable strategy for extending the thermal stability and lifespan of solid-lubricating films. Full article

This study aimed to design self-adhesive cutaneous films with an antiallergic effect using a Design of Experiments approach. The active pharmaceutical ingredient (API) was diphenhydramine hydrochloride (DPH). A full factorial experimental design with three factors and two levels was created. The factors were the polyvinyl alcohol (PVA) ratio, the polyacrylic acid (PAA) ratio, and the type of plasticizer. The responses evaluated were hardness, deformation at hardness, adhesive force, and in vitro DPH release profile. Eleven formulations were generated, prepared in two steps via solvent casting, and characterized in terms of mechanical and adhesive properties, as well as the in vitro DPH release profile. The PVA ratio had the most significant impact on the responses, followed by PEG 400 and PEG 4000. Four film formulations were investigated using Raman spectroscopy, which revealed that the API was distributed in both the base and adhesive layers. Consequently, an optimal formulation was prepared and characterized. Good mechanical properties (a hardness of 463.7 g and a deformation at hardness of 16.56 mm) and an increased adhesive force (76 g) were observed, while the DPH was released up to 68% over 12 h. In conclusion, a novel self-adhesive film was developed, which may enhance patients’ adherence to local antiallergic treatment. Full article

Aiming at the unclear bearing mechanism of the single-layer lining structure of high-performance fiber shotcrete under layered construction in the hard rock section of a highway tunnel, this paper studies the effect of different thickness ratios under layered construction on the flexural performance of the single-layer lining structure. Six types of thickness ratio specimens were subjected to a four-point bending test. The tests employed 3D digital image correlation technology to record and analyze the deformation and failure process of the specimens, and the calculation method of single-layer lining flexural stiffness was modified. The results indicate that the flexural ultimate load of the specimens is achieved at a thickness ratio of 2, which is 20.9% higher compared to a thickness ratio of 0. Layered construction affects the failure mode of the specimens. All specimens exhibit mixed-mode failure. However, with the increase in the thickness ratio, the percentage of flexural failure cracks gradually increases. Under layered construction, the reduction in the effective bending stiffness of fiber shotcrete beams becomes more pronounced as the thickness ratio increases. Based on these findings, the interface influence factor is proposed, and the flexural stiffness is corrected using composite beam theory. Full article

This work shows an approach on the role of the gas mixture used in the pulsed DC plasma nitriding aiming to enhance the niobium cavitation erosion resistance through the formation of niobium nitride on the treated surfaces. For this purpose, nitriding was carried out at 1353 K (1080 °C) for 2 h, under a pressure of 1.2 kPa (9 Torr), and a 5 × 10⁻⁶ Nm³s⁻¹ (300 sccm) flow rate for three distinct gas mixtures, namely 30% N₂ + 50% H₂ + 20% Ar, 50% N₂ + 30% H₂ + 20% Ar, and 70% N₂ + 10% H₂ + 20% Ar. Surfaces were comparatively characterized before and after nitriding through scanning electron microscopy (SEM), X-ray diffractometry, 3D roughness, and nanoindentation hardness measurements. The cavitation erosion test was carried out in accordance with ASTM G32-09, obtaining the cumulative mass loss (CML) curve and the average (AER) and maximum (MER) erosion rate of the tested surfaces. Surfaces showed multiphase layers mainly constituted of ε-NbN and β-Nb₂N nitride phases, for the three distinct gas mixture conditions investigated. A CML of 25.0, 20.2, and 34.6 mg, and an AER of 1.56, 1.27, and 2.16 mg h⁻¹ was determined to the 960 min (16 h) cavitation erosion testing time, for NbN surfaces obtained at the 30% N₂, 50% N₂, and 70% N₂ gas mixture, respectively. In this case, the nominal incubation period (NIP) was 600, 650, 550 min, and the maximum erosion rate (MER) was 4.2, 3.4, and 5.1 mg h⁻¹, respectively. Finally, the enhancement of the cavitation erosion resistance, based on the NIP of the NbN surfaces, regarding the Nb substrates (with NIP of ≈100 min), was up ≈6 times, on average, thus significantly improving the cavitation erosion resistance of the niobium. Full article