Search Results (5,228)

Marine deck coatings suffer from premature failures such as wear thinning, flaking, and brittle cracking under repeated rolling, abrupt stopping/steering, and high shear loads of heavy equipment due to the imbalance of hardness, strength, toughness, and wear resistance. To address this issue, a rolling load-resistant coating system with an epoxy–amine/epoxy–thiol dual-crosslinked network was constructed using liquid polysulfide rubber (Lp-3) as the key crosslinking modifier, and the effect of Lp-3 content (0–2 wt%) on the comprehensive performance of the coating was systematically investigated. The results showed that the coating achieved the optimal synergy of properties at 1 wt% Lp-3 loading: Shore hardness reached 88.7 HD with the pencil hardness maintained at 8H, adhesion strength increased to 7.2 MPa, Taber abrasion loss significantly decreased to 14.8 mg, tensile strength rose from 5.5 MPa to 12.4 MPa, elongation at break nearly doubled, shear strength reached 10.2 MPa, and the failure mode transformed from brittle cleavage to ductile shear. Mechanistic analysis revealed that the terminal thiol groups of Lp-3 underwent a click reaction with epoxy groups, covalently embedding flexible polysulfide segments into the rigid epoxy network and forming Fe–S interfacial chemical bonds to enhance adhesion. The microphase separation, chain relaxation, and energy dissipation mechanisms effectively blunted crack propagation and alleviated stress concentration, while maintaining sufficient surface hardness and the continuity of the load-bearing skeleton. This work realizes the synergistic optimization of high strength, high toughness, strong adhesion, and excellent wear resistance for marine deck coatings and provides a new strategy and critical technical parameters for the design of functional coatings under heavy-duty dynamic service environments. Full article

Ti6Al4V alloy is widely used in biomedical and engineering applications; however, its limited wear resistance and lack of intrinsic antibacterial activity restrict its long-term performance. Although multi-element nitride coatings prepared by cathodic arc evaporation (CAE) have shown considerable potential, the influence of substrate bias voltage on their microstructural evolution and multifunctional performance remains insufficiently understood. In this study, (TiCrCuZrAlAg)N multi-element nitride coatings were deposited on Ti6Al4V substrates by CAE under substrate bias voltages of 50, 100, and 150 V. The effects of bias voltage on coating composition, crystal structure, hardness, wear behavior, and antibacterial performance were systematically investigated. Increasing the bias voltage enhanced ion bombardment, leading to reduced coating thickness, lower Cu/Ag incorporation, and degraded crystallinity, which consequently affected coating performance. Among the investigated conditions, the coating deposited at 50 V exhibited the highest hardness (1628.4 HV), the lowest wear rate (0.08 × 10⁻⁷ g/m), and the highest antibacterial efficiency (99.2%). This study establishes a correlation between substrate bias voltage, microstructural evolution, and multifunctional performance in CAE-deposited (TiCrCuZrAlAg)N coatings, providing practical guidance for the design of multifunctional protective coatings. Full article

Background: In the field of minimally invasive restorative dentistry, ultrathin (<0.5 mm thickness) ceramic occlusal veneers are increasing being used as alternatives to full-coverage crowns, particularly for mild occlusal wear and not deep caries. However, only limited research attention has been given to how marked reduction in the thickness of a veneer restoration affects its mechanical performance. The purpose of the present in vitro study was to compare the performance of restorations that comprised a 0.3 mm thick zirconia veneer to the case when a lithium disilicate veneer was used, under quasi-static compressive loading. Methods: Forty extracted human molars, without caries, cracks or fractures and with intact coronal structure, were randomly assigned to two groups: lithium disilicate occlusal veneers (n = 20) and zirconia occlusal veneers (n = 20). The teeth were embedded in acrylic resin up to the cementoenamel junction. Digital scans were used to record the original anatomy and guide restoration design. Standardized occlusal preparations were performed using a 0.3 mm reduction protocol and verified with silicone guides to support a biomimetic, tooth-preserving approach. After preparation, the teeth were rescanned, and restorations were designed and fabricated using CAD/CAM technology. Lithium disilicate restorations were milled from Ivoclar Porcelain System [IPS], esthetic maximized [e.max] computer-aided design [CAD] blocks, whereas zirconia restorations were milled from Prettau 3 zirconia discs. Restorations were adhesively cemented with dual-cure resin cement following material-specific surface treatment protocols. Fracture resistance was tested using a universal testing machine under compressive loading until failure. Results: The fracture loads with lithium disilicate and zirconia occlusal veneers were 481.45 ± 68.23 N and 720.93 ± 95.44 N, respectively. Fracture was catastrophic in lithium disilicate occlusal veneers whereas it was not so when zirconia veneer was used. Conclusion: Quasi-static compressive fracture load when a lithium disilicate veneer was used was significantly lower than when a zirconia veneer was used. Full article

This study evaluated the effect of sports and energy drinks on the surface roughness of three commonly used restorative dental materials: resin-based composites (RBCs), resin-modified glass ionomer cements (RMGICs), and conventional glass ionomer cements (GICs). Sixty-three A2-shade specimens of each material were fabricated, stored in distilled water for 24 h, and then immersed in six commercially available beverages or distilled water (control) for 6, 30, or 60 h. Surface roughness was assessed after each immersion period using contact profilometry, and the effects of material type, immersion medium, and exposure time were compared. Surface roughness increased with longer immersion times for all materials, although the magnitude of change varied significantly among material types. RBCs showed the greatest resistance to surface degradation, whereas RMGICs and particularly GICs exhibited progressively higher roughness values over time. Beverages generally produced greater surface roughness than distilled water, with sugar-containing formulations showing higher roughness values than their sugar-free counterparts. Prolonged exposure to sports and energy drinks may adversely affect the surface integrity of restorative materials. Resin-based composites demonstrated the highest resistance to roughness changes, whereas glass ionomer cements were the most susceptible. Increased surface roughness may contribute to plaque accumulation, staining, and material wear, potentially compromising the long-term clinical performance of restorations. Full article

This study proposes an integrated finite element methodology for evaluating and redesigning three critical subsystems of an XCMG XC740K skid-steer loader: the excavation attachment, the arm–bucket charging system, and the ROPS/FOPS operator protection cab. The components were reconstructed by reverse engineering and 3D scanning, modeled in CAD, and simulated in ANSYS Workbench/Mechanical under load cases derived from hydraulic parameters, soil–tool interaction, and international safety standards. The novelty of the work lies in applying a single FEM-based workflow to three interacting subsystems of the same compact machine, rather than optimizing isolated components independently. The original configuration showed critical effort concentrations in the cab and charging system. Localized geometric reinforcements and the use of high-strength and wear-resistant steels improved stiffness and safety margins in the excavation bucket, loading bucket, and ROPS/FOPS cab. However, the arm–quick coupler region remained the controlling weak point of the loading assembly, indicating the need for further redesign. The proposed approach provides a transferable computational framework for identifying structural vulnerabilities and prioritizing redesign actions in compact earthmoving machinery. Because the study is numerical, future experimental validation is required before certification or field implementation. Full article

Sapphire crystal, owing to its high hardness, chemical inertness, thermal stability, optical transparency, and superior dielectric strength, as well as resistance to scratching, abrasion, friction, and wear, is widely utilized in a broad range of engineering applications. Slicing is the most critical step in sapphire industry processing, as it largely dictates the final surface quality and morphology. Conventional wire sawing methods often lead to undesirable surface defects, while ultrasonic-assisted diamond wire sawing (UADWS) offers potential advantages through enhanced abrasive self-sharpening, micro-hammering, and improved lubricant penetration. However, its influence on sapphire slicing remains insufficiently studied. This study investigates the effects of UADWS parameters—ultrasonic amplitude, horn application position, feed speed, and wire speed—on the surface quality of sapphire crystals. Both single-factor and orthogonal five-level experiments were designed, taking wire and feed speed within industrial parameter ranges. Surface roughness (Ra) and waviness peak–valley (PV) difference were used as evaluation indices, and range and variance analyses were performed. In addition, power regression models were developed to predict Ra and PV under varying conditions. The surface morphology results from single-factor experiments reveal that increasing feed speed and wire speed reduces the effectiveness of ultrasonic assistance, while application horn position exerts only a minor influence. Overall, orthogonal analysis confirmed that the relative influence of process parameters on surface quality follows the order: feed speed > wire speed > amplitude > application horn position. These findings establish a foundation for optimizing the sawing and ultrasonic parameters of UADWS to enhance sapphire surface quality, reduce downstream processing requirements, and clarify the importance of controlling feed speed and wire speed. Full article

The giant panda (Ailuropoda melanoleuca) relies on bamboo as its principal food source, exposing its enamel to sustained indentation, shearing, and abrasive loading. Mature enamel is highly mineralized but retains a small residual organic phase, whose contribution to wear resistance remains insufficiently defined. A gradient deproteinization model of mature giant panda enamel was established using KOH treatment. Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to verify organic-phase removal and mineral-framework preservation. Nanoindentation, indentation creep, nanoscratch testing, atomic force microscopy (AFM), and SEM were then used to evaluate mechanical response, scratch resistance, and surface morphological evolution. The mass loss within 200–450 °C decreased with increasing KOH exposure and reached a plateau after 9 days. FTIR showed reduced organic-related or surface-sensitive bands, whereas phosphate bands were retained. XPS revealed decreased C and N contents; increased O, Ca, and P contents; and a higher Ca/P ratio. Deproteinization decreased the elastic modulus, shifted load–displacement curves toward greater indentation depth, and reduced the relative creep index. The critical load in nanoscratch testing decreased from 12.53 ± 0.35 mN to 6.07 ± 0.77 mN, while scratch depth, width, and residual depth increased. AFM showed a rightward shift in aggregate-size distribution and increased roughness. SEM revealed a transition from shallow plowing grooves to complex damage involving cracks, debris accumulation, and local spallation. Therefore, KOH treatment for 9 days provided an effective deproteinization endpoint for mature giant panda enamel. These findings suggest that the residual organic phase may contribute to surface interfacial continuity, local deformation accommodation, scratch-damage resistance, and reduced permanent damage accumulation. This material role may contribute to the adaptation of giant panda enamel to the mechanical demands of a bamboo-based, high-wear diet. Full article

H13 tool steel is widely used in precision injection molds; however, severe wear in confined regions, such as ejector pin holes, limits its service life, while conventional strengthening techniques remain difficult to apply in these areas. In this study, a combined plasma nitriding and oblique laser shock peening (OLSP) treatment was proposed, and the effects of laser incidence angle on microstructure, mechanical properties, and wear behavior were systematically investigated through electron backscatter diffraction (EBSD), X-ray diffraction (XRD) residual stress analysis, and ball-on-disk (BOD) wear tests. The results demonstrate that OLSP promotes grain refinement, dislocation accumulation, and the introduction of high-magnitude compressive residual stress. The NLSP1 sample exhibited the optimum strengthening effect, with a maximum compressive residual stress of −1033 MPa. It also achieved the lowest wear depth, wear volume, and specific wear rate, with a specific wear rate of 1.64 × 10⁻⁶ mm³/(N·m), representing a 54.3% reduction compared with the untreated sample. The enhanced wear resistance was attributed to the synergistic effects of hardness improvement, microstructural refinement, and compressive residual stress. These findings demonstrate that optimizing the laser incidence angle can improve strengthening efficiency and provide an effective strategy for surface modification of critical regions in complex molds. Full article

Conventional roadheader cutting tools are subjected to substantial forces, intense impacts, and friction during rock excavation, resulting in excessive energy consumption and accelerated tool wear. To address these challenges, undercutting technology has emerged as a promising alternative for integrating disc cutters into roadheaders. In this study, a comprehensive mechanical investigation is conducted on an Oscillating Disc Cutter (ODC) based on the undercutting principle to enhance fragmentation efficiency and minimize energy requirements. A high-fidelity numerical framework, coupling the Finite Element Method (FEM) and Smoothed Particle Hydrodynamics (SPH), is established to simulate the dynamic ODC cutting process. This model is rigorously validated against both theoretical analyses and experimental data. Results demonstrate that the ODC can reduce the minimum specific energy by 78% compared to conventional non-eccentric cutters and attenuates the average rolling, side, and normal forces by 70.9%, 59.4%, and 67.9%, respectively. Furthermore, parametric analysis reveals a strong sensitivity of cutting performance to oscillation frequency and feed rate. These findings confirm that the ODC mechanism effectively mitigates cutting resistance and optimizes rock fragmentation, providing essential theoretical and practical guidance for the development of high-efficiency underground excavation equipment. Full article

Against the background of severe wear failure of Rotary Tillage blades restricting agricultural tillage efficiency, this study aimed to explore wear resistance differences, reveal wear mechanisms and locate critical failure zones to support blade material selection, structural optimization and localized strengthening. Five commercial IT195 Rotary Tillage blades made of 65Mn and 60Si2Mn steels were tested via a soil-bin rotary wear test rig. Microstructure, hardness and wear morphology were characterized by metallographic microscopy, Vickers hardness test and SEM, while 3D scanning and stress simulation were adopted to analyze full-cycle wear behavior of the optimal blade. The results showed that the E-type blade with 60Si2Mn possessed the best wear resistance, with minimum mass and dimensional wear loss and the gentlest wear rate, attributed to its single-phase acicular martensite and high hardness of 627.73 HV, forming uniform shallow grooves and suppressing micro-cutting and spalling. Full-cycle wear analysis demonstrated highly uneven wear distribution, with the bend transition zone linking tangential and side cutting regions identified as the critical failure zone featuring the largest wear depth and fastest material loss, verified by stress concentration from simulation. This work provides theoretical support and targeted references for material optimization, structural design and surface strengthening of key regions of Rotary Tillage blades. Full article

Tantalum (Ta) is an excellent alternative for structural orthopedic implants because of its high biocompatibility and chemical stability, but its melting point of 3020 °C severely complicates conventional casting. To address this, the study evaluates spark plasma sintering (SPS) to consolidate pure Ta powders at 1450 °C and 50 MPa and analyzes the impact of heating rates (50–200 °C/min) on microstructural, mechanical, wear, and corrosion properties. Results indicate that heating rate dictates final densification: a 50 °C/min rate achieved 98.59% relative density, whereas 200 °C/min yielded only 82.28% due to reduced thermal exposure. Sintering involved dislocation creep and viscous flow mechanisms, with X-ray diffraction confirming a stable α-Ta matrix across all samples. Mechanically, the 50 °C/min samples achieved a maximum microhardness of 285 HV, whereas higher porosity at 200 °C/min reduced hardness by 27.8%. Wear testing showed a two-stage friction evolution: an initial Ta₂O₅ solid-lubricating effect, followed by predominant abrasion and adhesion, with stable wear rates (3.2 to 3.6 × 10⁻³ mm³/N·m) for dense specimens. Finally, tests in simulated body fluid confirmed spontaneous self-passivation. However, the corrosion rate increased with heating rates, indicating that the resulting porosity adversely affects the material’s surface response. Full article

The use of aluminium alloys in internal combustion engines is an effective strategy for increasing energy efficiency, reducing component mass, and lowering harmful gas emissions. This paper analyses different types of Al–Si alloys (hypoeutectic, eutectic, and hypereutectic) in the context of their use in the production of engine blocks, pistons, and cylinder liners. Special attention is given to the tribological challenges of using aluminium, such as increased wear and lower strength compared to traditional materials such as cast iron. Modern methods for improving wear resistance are discussed, including alloying, the application of solid lubricants and protective coatings (Ni–SiC, Al₂O₃, MoS₂, etc.), and advanced surface engineering technologies such as PTWA, HVOF, and laser alloying techniques. This paper also presents practical examples of industrial applications, highlighting their essential role in the development of lightweight, high–performance internal combustion engines. This review highlights that the combination of optimized alloy composition and advanced surface engineering technologies represents the most effective approach for enhancing the durability and tribological performance of lightweight engine components. Full article

In recent years, the quest for advanced materials has intensified, driving the exploration of innovative coating systems to enhance material properties. Polymeric materials, renowned for their adaptability, have found extensive use across various industries. However, their inherent limitations in mechanical strength, wear resistance, and thermal stability have prompted researchers to seek enhancement avenues. Hybrid polymeric–metallic coatings have emerged as a promising solution, employing thermal spray techniques to metalize polymeric substrates. This amalgamation utilizes the versatility of thermal spraying methods, ranging from cold spraying, flame spraying, arc spraying, to plasma spraying, to achieve robust adhesion between metal and polymer layers. These techniques yield durable composite structures, fortifying surfaces against corrosion and wear while enabling dimensional restoration. Cold spraying, in particular, stands out among thermal spray methods due to its effectiveness in metalizing various materials. This comprehensive review delves into recent advancements in hybrid polymeric–metallic coatings via thermal spray processes. Emphasis is placed on analyzing critical factors influencing coating properties, including various thermal spray parameters. Furthermore, the paper scrutinizes the challenges and future potentials inherent in thermal spray techniques, with a focused exploration of cold spray technology. Understanding these methodologies is pivotal for optimizing the design and durability of structural materials made of polymers or composites. Full article

Electroless coatings mark a significant improvement in surface engineering by providing superior uniformity, precision, and functional properties compared with traditional plating processes. Electroless Ni-P-Al₂O₃ composite coatings were successfully deposited on Ti-6Al-4V, forming a Ni-Ti intermediate (~14–16 µm) that ensured strong interfacial bonding. Al₂O₃ concentration (0.2–1.4 g/L) strongly influenced microstructure and performance, with 0.4 g/L yielding the most refined coating. AFM revealed a dense, uniform surface with the lowest roughness (~23.4 nm). This composition achieved the highest hardness (464.6 HV_0.1), ~157% higher than the substrate and ~53% higher than Ni-P. It also showed superior tribological behavior, reducing wear volume to ~4.46 × 10⁻⁷ mm³ and friction coefficient to ~0.32 (~85% and ~50% reductions vs. substrate). Corrosion resistance was maximized at 0.4 g/L, with the lowest corrosion current (2.45 × 10⁻⁶ A/cm²) and rate (0.0053 mpy), outperforming both Ni-P and uncoated Ti-6Al-4V due to the compact composite matrix and stable passive film. Full article

High-wear-resistant iron-based clad layers demonstrate substantial application potential in aerospace, automotive, and industrial equipment due to their excellent mechanical properties and extended service life. Laser cladding has emerged as a pivotal technology for the additive manufacturing and repair of critical components, characterized by rapid cooling rates, narrow heat-affected zones, and dense microstructures. However, fabricating high-wear-resistant Fe-based clad layers remains challenging, particularly in achieving a trade-off among hardness, wear resistance, and toughness. Excessively high hardness often compromises toughness, increasing susceptibility to cracking and reducing service reliability, whereas insufficient hardness undermines functional performance and shortens service life. This review synthesizes recent advances in microstructural design, control, and optimization of high-wear-resistant Fe-based clad layers, focusing on powder alloying design, process parameter optimization, and post-cladding strengthening treatments. The strengthening mechanisms and performance characteristics of key alloying elements, specifically Cr, B, Nb, Mo, and Ti, are summarized, and the effects of laser power, scanning speed, and powder feeding rate on the microstructure and properties are systematically discussed. Furthermore, the influence of post-treatment processes, including turning, grinding, ultrasonic rolling, and heat treatment, on wear resistance enhancement is also addressed. Finally, future development directions for laser cladding of high-wear-resistant Fe-based clad layers are proposed. Full article