Search Results (5,063)

Anti-icing materials have attracted considerable research interest due to their potential applications in preventing ice accretion and growth. However, a major challenge in the field is how to enhance durability while maintaining anti-icing performance. This study proposes a facile fabrication method for anti-icing coatings with anti-aging and self-healing abilities. A three-dimensionally cross-linked block copolymer, synthesized from polydimethylsiloxane, 4-aminophenyl disulfide, and trimethylolpropane triglycidyl ether, yielded a coating with excellent anti-icing/de-icing performance, including a low ice adhesion strength (29.2 kPa) and a high icing delay time (1389 s). The introduction of 4-aminophenyl disulfide enables dynamic disulfide bond reorganization and aromatic framework formation, synergistically conferring the icephobic coating with self-repair mechanisms and an anti-aging function. The coating exhibited a rapid self-healing capability (within 4 h), which is facilitated by the dynamic exchange of its hydrogen and disulfide bonds. Furthermore, the material demonstrated outstanding durability against physical wear and ultraviolet radiation. After being subjected to a 1000-cycle abrasion test and ultraviolet aging, the coating successfully retained more than 70% of its original performance in both icing delay time and ice adhesion strength. This paper proposes a facile strategy for developing self-healing and anti-aging anti-icing coatings and proposes innovative strategies for multifunctional anti-icing coatings. Full article

Tool steels are critical for high-load applications, e.g., forging and metal-forming, where they face thermal cracking, fatigue, erosion, and wear. This study evaluates the impact of gas nitriding and S-phase PVD coatings on the mechanical and tribological properties of four tool steels: 40CrMnNiMo8-6-4, 60CrMoV18-5, X50CrMoV5-2, and X38CrMoV5-3. Samples were heat-treated (quenched and tempered at 600 °C), then gas-nitrided at 575 °C for 6 h with nitriding potentials (Kn) of 0.18, 0.79, or 2.18, or coated via reactive magnetron sputtering in Ar/N₂ or Ar/N₂/CH₄ atmospheres at 200 °C or 400 °C. Characterization involved XRD, LOM, FE-SEM, GDOES, Vickers hardness (HV0.1), and ball-on-disk wear testing with Al₂O₃_ counter-samples. Gas nitriding produced nitrogen diffusion layers (80–200 μm thick) and compound layers (ε-Fe_(2-3)N, γ’-Fe₄N) at higher Kn, increasing hardness by 80–100% (up to 1100 HV0.1 for steel X38CrMoV5-3). S-phase coatings (1.6–3.6 μm thick) formed expanded austenite with varying N content, achieving comparable hardness (up to 1100 HV0.1) in high-N₂ atmospheres, alongside substrate diffusion layers. Both types of treatment enhance load-bearing capacity, adhesion, and durability, offering superior wear resistance compared to conventional PVD coatings and addressing demands for extended tool life in industrial applications. Full article

Grey cast iron brake discs are widely used in automotive applications due to their excellent thermal and mechanical properties. However, stricter environmental regulations such as Euro 7 demand improved surface durability to reduce particulate emissions and corrosion-related failures. This study evaluates multilayer coatings fabricated by Laser Metal Deposition (LMD) as a potential solution. Two multi-layer systems were investigated: 316L + (316L + WC) and 316L + (430L + TiC), which were primarily reinforced with ceramic additives to increase wear resistance, with their influence on corrosion being critically evaluated. Electrochemical tests in 5 wt.% NaCl solution (DIN 17475) revealed that the 316L + (316L + WC) coating exhibited the lowest corrosion current density and most stable passive behavior, consistent with the inherent passivation of the austenitic 316L matrix. In contrast, the 316L + (430L + TiC) system showed localized corrosion associated with micro-galvanic interactions, despite the chemical stability of TiC particles. Post-corrosion SEM and EDS confirmed chromium depletion and chloride accumulation at corroded sites, while WC particles exhibited partial dissolution. These findings highlight that ceramic reinforcements do not inherently improve corrosion resistance and may introduce localized degradation mechanisms. Nevertheless, LMD-fabricated multilayer coatings demonstrate potential for extending brake disc service life, provided that matrix–reinforcement interactions are carefully optimized. Full article

Background/Objectives: Super translucent zirconia (ST zirconia) is increasingly used for esthetic restorations, but its optical stability after mechanical wear remains unclear. This study aimed to evaluate the effects of three finishing protocols—polishing, glazing, and staining followed by glazing (Chroma + Glaze)—on the color stability and translucency of ST zirconia after simulated toothbrushing. Methods: Sixty zirconia specimens (Vita YZ ST, shade A1) were fabricated and divided into three groups, namely Polished, Glazed, and Chroma + Glaze (n = 20 in each group). Color (L*, a*, b*) was measured using a spectrophotometer (VITA Easyshade V; VITA Zahnfabrik) before and after 10,000 brushing cycles (200 g load, 1.5 Hz). Translucency parameters (TP_ab, TP₀₀) were calculated, while color changes were assessed using CIELAB (ΔE_ab) and CIEDE2000 (ΔE₀₀) formulas. Data were analyzed using two-way ANOVA and Kruskal–Wallis tests (α = 0.05). Results: Treatment significantly affected translucency (H = 46.79, p < 0.001; H = 21.09, p < 0.001), indicating consistent differences among the three treatment groups. Bonferroni-adjusted post hoc comparisons showed that Chroma + Glaze exhibited significantly lower TP₀₀ values than Glaze in both measurements (p < 0.0001; p <0.001), as well as lower values than Polished in both measurements (p < 0.0001; p = 0.0147, respectively). Kruskal–Wallis analysis revealed significant differences among finishing protocol groups for both ΔE_ab (H =13.21, p < 0.0014) and ΔE₀₀ (H = 9.14, p = 0.0104), with Chroma + Glaze exhibiting the smallest ΔE values (ΔE₀₀ ≈ 0.33) below the perceptibility threshold. Conclusions: The finishing protocol significantly influences the optical behavior of ST zirconia after simulated wear. The Chroma + Glaze group demonstrated the highest color stability and lowest translucency, suggesting enhanced long-term esthetic performance. In contrast, polished zirconia showed greater color variation and an increase in translucency, indicating lower optical stability under brushing abrasion. Full article

Machining nickel-based superalloys, such as Inconel 718, poses a significant technological challenge due to their high-temperature strength and low thermal conductivity, leading to rapid tool wear. This paper presents a comprehensive comparative analysis of two roughing strategies: high-feed milling and plunge milling, utilizing a unique custom-designed milling head. The primary objective was to evaluate the impact of tool material reinforcement on the process by comparing SiC whisker-reinforced ceramic inserts (CW100) with non-reinforced inserts (CS300). The experiment involved measuring cutting force components, power consumption, and analyzing tool wear progression (VBB) and mechanisms. Results showed that the presence of the reinforcing phase is critical for reducing the axial force component (Fz), particularly in plunge milling, where CW100 inserts achieved a 30–35% force reduction and avoided the catastrophic failure observed in non-reinforced ceramics. Microscopic analysis confirmed that composite inserts undergo predictable abrasive wear, whereas CS300 inserts are prone to brittle fracture and spalling. Multi-criteria optimization using Grey Relational Analysis (GRA) identified high-feed milling with reinforced inserts as the most efficient strategy, while also positioning plunge milling with composites as a competitive, less energy-intensive alternative. Full article

To enhance the abrasion resistance of TC4 titanium alloy and meet the demand for wear-resistant and corrosion-resistant friction pair materials for water-hydraulic components of marine equipment, the tribological properties of the material subsequent to ultrasonic rolling extrusion surface strengthening under seawater-lubricated conditions were investigated. The process of ultrasonic rolling machining was simulated and analyzed by the finite element method. The influence of process parameters on surface residual stress and surface roughness of TC4 was studied, and the appropriate range of process parameters was determined. The effects of key process parameters such as rolling times, static pressure, amplitude, and rotational speed on the surface properties of TC4 were investigated by the single-factor test method. Based on the response surface methodology, a prediction model of surface hardness and roughness of TC4 was constructed, and the process parameters were optimized and analyzed. The friction coefficient, wear amount, and wear rate of TC4 and CFRPEEK under seawater lubrication before and after strengthening were studied by wear tests. The wear morphologies of the specimens prior to and subsequent to strengthening were analyzed, and the friction and wear mechanisms were explored in depth. The results indicate that ultrasonic rolling extrusion surface strengthening process facilitates grain refinement in the surface layer of TC4, enhances surface hardness, and optimizes surface roughness, thereby improving its wear resistance. This is of guiding significance to the design and use of hydraulic components in seawater and has a promoting effect on the development of marine equipment. Full article

This article explores whether jerk, the derivative of acceleration, should be limited in trajectory planning for position-controlled mechanical systems or in the controller. The excess jerk excites structural resonances and increases actuator wear, motivating the use of a limited jerk. However, we question the necessity of incorporating the jerk directly in trajectory planning by comparing third-order jerk-limited trajectories with second-order trajectories with reduced controller bandwidth that regulate torque gradients. We demonstrate by a typical practical application that reducing controller bandwidth can achieve comparable or superior jerk reduction without extending overall motion time for point-to-point trajectories. As a result, second-order parabolic trajectory profiles simplify on-line implementation. This investigation relies on a detailed sensitivity analysis of a one-dimensional model, incorporating crucial elements such as signal and sensor quantisation, sampling, and modes of structural resonances. The study shows that smooth trajectories reduce resonant vibrations and wear, but the jerk limitation may be addressed more effectively within the controller rather than within the trajectory generator. We conclude that although the limitation of the jerk in the trajectories is valuable, feedback controllers can reduce the jerk more effectively by bandwidth reduction, allowing simpler point-to-point trajectory designs without compromising performance. Full article

Intermetallic Fe₃Al-based alloys reinforced with Laves-phase precipitates are emerging as potential replacements for conventional high-alloy steels and possibly polycrystalline Ni-based superalloys in structural applications up to 700 °C. Their impressive mechanical properties, however, are offset by limited fabricability and poor machinability due to their severe brittleness. High tool wear during finish-machining, which is still required for components such as turbine blades, remains a key barrier to their broader adoption. In contrast to conventional manufacturing routes, additive manufacturing offers a viable solution by enabling near-net-shape manufacturing of difficult-to-machine iron aluminides. In the present study, laser powder bed fusion was used to produce an Fe-25Al-1.5Ta intermetallic containing strengthening Laves-phase precipitates, and the porosity, microstructure and phase composition were characterized as a function of the process parameters. The results showed that preheating the build plate to 650 °C effectively suppressed delamination and macrocrack formation, even though noticeable cracking still occurred at the high scan speed of 1000 mm/s. X-ray tomography revealed that samples fabricated with a lower scan speed (500 mm/s) and a higher layer thickness (0.1 mm) contained larger, irregularly shaped pores, whereas specimens printed at the same volumetric energy density (40 J/mm³) but with different parameter sets exhibited smaller fractions of predominantly spherical pores. All samples contained mostly elongated grains that were either oriented close to <001> relative to the build direction or largely texture-free. X-ray diffraction confirmed the presence of Fe₃Al and C14-type (Fe, Al)₂Ta Laves phase in all samples. Hardness values fell within a narrow range (378–398 HV10), with only a slight reduction in the specimen exhibiting higher porosity. Full article

Chromium nitride (Cr-N) coatings fabricated by physical vapor deposition (PVD) have gained significant interest in the field of surface protection with the exceptional hardness, robust adhesion to substrates, and superior wear resistance. The mechanical properties of Cr-N coatings are predominantly determined by their chemical composition, phase structure, and microstructure. The selection of deposition technique and regulation of process parameters, such as N₂ flow rate, play a crucial role in optimizing coating performance. This review systematically summarizes recent research advancements in PVD-fabricated Cr-N coatings with a specific focus on both monolayer and multilayer architectures. It explores the impact of process parameters on the hardness, adhesion strength, and tribological properties. Furthermore, it outlines the design strategies and fabrication methodologies for high-performance Cr-N coatings. Results indicate that the mechanical properties of monolayer Cr-N coating are primarily governed by the process parameters. As for multilayer coatings, the incorporation of ductile Cr layers can enhance the coating-substrate adhesion strength and wear resistance while preserving a relatively high hardness. This study aims to provide a theoretical foundation and technical reference for future research and applications of the Cr-N coating material system. Full article

Background and Objectives: Elastodontic appliances made of medical-grade silicone are increasingly used in interceptive orthodontics, but prolonged intraoral exposure may affect their stability. This study evaluated structural changes in LM-Activator^TM 2 appliances after clinical use, using Fourier-transform infrared (FTIR) spectroscopy. Materials and Methods: Eight appliances (one unused control and seven worn for 3–24 months) were analyzed by FTIR-ATR in the 4000–650 cm⁻¹ range. Absorption bands characteristic of polydimethylsiloxane (PDMS) were quantified, and indices reflecting backbone crosslinking, side-group retention, hydrophilicity, and relative reduction in methyl-related spectral contributions were calculated. Results: The PDMS backbone remained chemically intact across all samples. However, progressive molecular reorganization was detected with wear duration. The Backbone Dominance Index increased significantly from control to 24 months, while side-group indices decreased, confirming apparent depletion of methyl-related FTIR bands. Hydrophilicity and crosslinking indices rose over time, particularly after 12 months, indicating increased surface polarity and network densification. Conclusions: LM-Activator^TM 2 appliances undergo gradual intraoral aging, marked by backbone crosslinking and apparent reduction in methyl-associated vibrational contributions inferred from FTIR ratio side-groups. These changes, while not compromising the polymer identity, may influence surface properties, biofilm retention, and long-term mechanical behavior. Periodic replacement is recommended to ensure optimal clinical performance. Full article

To enhance the operational damage resistance of hydraulic machinery, this study employed laser cladding technology to fabricate a Co_37.4Cr₃₀Ni₂₀Al₅Ti₅Nb_2.6 high-entropy alloy coating on 04Cr₁₃Ni₅Mo substrate. The influence of laser power on the microstructure and properties of the coating was systematically investigated. Based on preliminary research, the friction-wear performance and cavitation erosion behavior of the coatings prepared at 3000 W, 3200 W, and 3400 W were specifically examined. Results indicate that as the laser power increased from 3000 W to 3400 W, the microhardness of the coating gradually decreased from 345.3 HV_0.2. At 3000 W, the precipitation of trace strengthening phases significantly enhanced the mechanical properties. In wear tests under a 20 N load for 30 min, the wear rate of the coating prepared at 3000 W was 1.41 × 10⁻⁴ mm³/(N·m), which is 13.5% lower than that of the 3200 W coating (1.63 × 10⁻⁴ mm³/(N·m)) and 16.07% higher in wear resistance compared to the substrate. Cavitation erosion tests revealed that after 20 h of ultrasonic vibration, the mass loss of the 3000 W coating was only 2.35 mg, representing an 88.89% reduction compared to the substrate (21.15 mg), and significantly lower than that of the 3200 W (4.57 mg) and 3400 W (3.85 mg) coatings. This study demonstrates that precise control of laser power can effectively optimize the cavitation erosion resistance of high-entropy alloy coatings, providing technical support for their application in harsh environments. Full article

Background and Objectives: Unstable distal clavicle fractures (Neer type II) have a relatively high risk of nonunion and often require operative fixation. Hook plates are widely used, particularly when the distal fragment is small or comminuted, because they provide strong vertical stability. However, hook plates are associated with subacromial irritation, acromial wear, and the need for routine implant removal. Distal locking plates with supplementary cerclage augmentation can achieve fixation without subacromial impingement and may reduce implant-related complications. This study aimed to compare clinical and radiologic outcomes of hook plates versus locking plates with or without cerclage augmentation for Neer type II distal clavicle fractures. Materials and Methods: In this single-center retrospective cohort, adult patients with Neer type II distal clavicle fractures who underwent open reduction and internal fixation between March 2021 and August 2022, with ≥6 months of follow-up, were reviewed. Patients were allocated into two groups according to implant: hook plate (Group 1, n = 16) and distal locking plate with or without cerclage augmentation (Group 2, n = 26). Primary outcomes were complication rate, radiographic union, and shoulder range of motion (ROM). Secondary outcomes included pain (PVAS) and functional scores (SANE, ASES, Constant, UCLA). Results: Forty-two patients were analyzed (locking n = 26, hook n = 16). Groups were comparable in age (51.3 ± 16.0 vs. 54.4 ± 17.1 years), follow-up (7.0 ± 4.0 vs. 8.4 ± 4.3 months), sex distribution, smoking status, and mechanism of injury. Radiographic union was achieved in 24/26 (92.3%) patients in the locking group and 14/16 (87.5%) in the hook group; two cases of nonunion or reduction failure occurred in each group (p = 0.612). Final patient-reported outcomes and ROM were similar between groups (e.g., ASES 68.2 ± 15.5 vs. 64.4 ± 18.3, Constant 57.3 ± 9.5 vs. 44.9 ± 20.5; all p > 0.05). Forward flexion tended to be higher in the locking group (138.9 ± 28.0° vs. 113.3 ± 36.7°, p = 0.182), although without statistical significance. No deep infection, peri-implant fracture, or hardware failure requiring unplanned revision was observed. Subacromial wear was identified in four patients (25%) in the hook plate group, whereas no such change was observed in the locking group. Conclusions: Both hook plates and distal locking plates (±cerclage) provided high union rates and satisfactory functional outcomes for Neer type II distal clavicle fractures. However, hook plates were associated with subacromial wear, whereas locking plate constructs avoided subacromial complications. When distal fragment purchase is feasible—or can be supplemented with cerclage augmentation—locking plate fixation represents a reliable first-line option, with hook plates reserved for cases with minimal distal bone stock or complex comminution. Full article

Additive manufacturing is increasingly integrated into dental technology, yet the mechanical performance of 3D-printed denture base resins remains strongly influenced by printing orientation and post-curing duration. This study evaluated the combined effect of three printing orientations (0°, 45°, 90°) and three post-curing times (30, 45, 60 min) on the flexural strength and surface microhardness of a denture base resin. Specimens designed in Blender and fabricated using NextDent Denture 3D+ resin were subjected to three-point bending tests (n = 5 per group) and Vickers microhardness measurements (n = 10 per group). One-way ANOVA assessed main and interaction effects. Printing orientation had a significant influence on flexural strength, with horizontally printed specimens exhibiting the highest values, whereas vertically printed specimens were consistently weaker. Post-curing time did not significantly affect flexural strength within any orientation. In contrast, microhardness increased progressively with longer post-curing durations, regardless of orientation, indicating continued surface polymerisation. Because flexural strength and hardness responded differently to curing duration, no single post-curing time was universally optimal; however, 0° printing consistently produced the strongest specimens for this resin–printer system. This trade-off is clinically relevant, because dentures require high flexural strength to resist fracture and sufficient hardness to minimise wear. Full article

This paper reviews tab-to-busbar interconnections in lithium-ion battery packs, focusing on resistance welding (RW), laser beam welding (LBW), and ultrasonic welding (USW). The functional roles of tabs and busbars and typical material choices (Al-, Cu-, and Ni-plated Cu) are outlined. Subsequently, the processes are compared in terms of heat input, interfacial metallurgy, electrical resistance, mechanical robustness, and manufacturability. USW, as a solid-state method, suppresses porosity and limits Al-Cu intermetallic growth, but is sensitive to thickness, stack geometry, and tool wear. LBW enables high-speed, automated production with precise energy delivery, yet requires careful control to mitigate spatter, porosity, and brittle IMCs in dissimilar joints. RW remains cost-effective and flexible but can suffer from electrode wear and variability with highly conductive stacks. This review also summarizes the effect of the busbar material (Al versus Cu) and thickness on the connection resistance and temperature increase under a high current. No single process is universally superior, and the selection should match the stack-up, reliability targets, and production constraints. This paper aims to provide an overview of recent and conventional research trends for each welding method and to introduce selected non-traditional approaches, thereby presenting a range of viable options for future applications. Full article

The pitting corrosion resistance and the tribological behaviour of a ferritic stainless steel with high Mo content (AISI 436) and a commonly employed austenitic stainless steel (AISI 304) are compared. Special attention was paid to the role of Mo in improving corrosion resistance of ferritic stainless steels. Since the surface condition is an important parameter related to the onset of pitting corrosion in the presence of chlorides, three different surface finishes were tested for both steels. Two commercial finishing grades and laboratory polishing down to 1 µm were compared. Moreover, the influence of surface condition on the tribological properties for both steels was also evaluated. The study demonstrates that surface finishing plays a decisive role in both the electrochemical and mechanical response of stainless steels. A comprehensive microstructural and tribological analysis reveals not only how commercial finishing treatments modify passive film behaviour, but also how they affect friction stability and wear mechanisms. Special emphasis is placed on the synergistic effect between molybdenum content, passive film integrity and manufacturing processes. The obtained results provide valuable insight for industrial applications where durability against chloride exposure and abrasion is critical. Full article