Search Results (2,441)

Nickel–tungsten carbide (Ni/WC) multi-pass fused cladding layers with different cerium (IV) oxide (CeO₂) contents were applied to Cr12MoV cold work tool steel surfaces using the coaxial powder feeding method for laser cladding. Scanning electron microscopy, energy spectrum analysis, X-ray diffraction, and wear experiments were conducted to study how adding CeO₂ to change the properties of WC-reinforced Ni-base composite coatings in turn alters the microstructure and properties of Cr12MoV cold work tool steel. The results show that laser cladding is effective when the process parameters are as follows: a power of 1500 W, a 24 mm defocusing distance, a 6 mm/s scanning speed, a 5 mm spot diameter, and a powder delivery of 0.1 g/s. Laser-fused cladding coatings are mainly composed of dendrites, crystalline cells, strips, and bulk microstructures. The addition of CeO₂ is effective at improving the microstructure and morphology of the coating—the size and distribution of the reinforcing phase change very significantly, and the shape changes from irregular and lumpy to spherical. With a 2% CeO₂ content, the enhanced phase, now spherical and white, is more diffusely distributed in the tissue. The maximum microhardness of the composite-coated specimen after the addition of CeO₂ is about 986 HV, which is approximately 20% higher than the hardness of the composite coating with no CeO₂ added. Full article

Fluoride prophylaxis is a cornerstone in preventing dental caries, a disease for which orthodontic patients are at high risk due to the reduced effectiveness of home oral hygiene and increased plaque accumulation. Recent evidence defines caries as polymicrobial, involving Streptococcus mutans, Lactobacilli, and emerging species such as Selenomonas sputigena. This prospective, randomized, controlled study evaluated professional topical fluoride in the form of gel and varnish in 68 patients aged 8–17 years wearing fixed orthodontic appliances. Participants were divided into three equal groups: two intervention groups and one control group. Clinical parameters (DMFT, salivary pH, PCR%) and microbiological analyses of plaque and saliva (oral Streptococci, S. mutans, S. sputigena, Lactobacilli, total bacterial count) were assessed at baseline (T0) and after 4 months (T1), following professional hygiene and fluoride application for the intervention groups. At T1, salivary pH increased in the gel group, and PCR% decreased significantly in all groups, with the most pronounced decrease observed in the varnish group. PCR analysis showed a higher rate of S. mutans and S. sputigena negativization in intervention groups. Culture-based analyses revealed reductions in oral Streptococci and Lactobacilli in intervention groups, while levels increased in controls. Overall, both clinical and microbiological variables indicated improvements in the fluoride-treated groups compared to controls, highlighting the efficacy of professional fluoride prophylaxis in orthodontic patients. Full article

Abrasive belt wear has an important impact on the dimensional accuracy and surface quality of parts. Accurate quantitative measurement of abrasive belt wear is an important basis for optimizing grinding process parameters, but also a very challenging task for abrasive belts with randomly distributed abrasive particles. In this paper, a quantitative method of determining wear state based on the life cycle surface images of the abrasive belt is proposed to evaluate its material removal ability in the grinding process. For blunted abrasive particles with extremely irregular shapes, TransUNet with a hybrid encoding of a CNN and transformer is adopted to obtain strong representation of complex features and high-precision segmentation boundaries. Three other U-net-based semantic segmentation networks are compared to prove the effectiveness of the trained TransUNet model. The number and area of blunted abrasive particles were calculated by connected domain and statistical methods. The proportion of worn abrasive particles and the wear area ratio when the service life of the abrasive belt is exhausted are about 74.29% and 3.06%, respectively. Full article

The header platform of a combine harvester is subjected to severe abrasive and corrosive wear from rice stalks and environmental factors, which significantly limits its service life and operational efficiency. Accurately predicting the complex distribution of this wear over time and across the platform’s surface, however, remains a significant challenge. This paper, for the first time, systematically establishes a quantitative mapping relationship from “material motion trajectory” to “component wear profile” and introduces a novel method for time-sequence wear validation based on corrosion color gradients, providing a complete research paradigm to address this challenge. To this end, an analytical model based on rigid-body dynamics was first developed to predict the motion trajectory of a single rice stalk. Subsequently, a full-scale Discrete Element (DEM) model of the header platform–flexible rice stalk system was constructed. This model simulated the complex flow process of the rice population with high fidelity and was used to analyze the influence of key operating parameters (spiral auger rotational speed, cutting width) on wear distribution. Finally, real-world wear data were obtained through in situ mapping of a header platform after long-term service (1300 h) and multi-period (0–1600 h) image analysis. Through a three-way quantitative comparison among the theoretical trajectory, simulated trajectory, and the actual wear profile, the results indicate that the simulated and theoretical trajectories are in good agreement in terms of their macroscopic trends (Mean Squared Error, MSE, ranging from 0.4 to 6.2); the simulated and actual wear profiles exhibit an extremely high degree of geometric similarity, with the simulated wear area showing a 95.1% match to the actual measured area (Edit Distance: 0.14; Hamming Distance: 1). This research not only confirms that the flow trajectory of rice is the determining factor for the wear distribution on the header platform but, more importantly, the developed analytical and numerical methods offer a robust theoretical basis and effective predictive tools for optimizing the wear resistance and predicting the service life of the header platform, thereby demonstrating significant engineering value. Full article

The current study focuses on axial ultrasonic vibration-assisted micro-milling as an advanced technique to improve the machining performance of Ti6Al4V, a material whose difficult-to-cut properties present a significant barrier to manufacturing the high-quality micro-components essential for aerospace and biomedical applications. A full factorial design was employed to evaluate the influence of feed-per-tooth (f_z), axial depth-of-cut (a_p), and ultrasonic vibration on cutting forces, surface roughness, burr formation, and tool wear. Experimental results demonstrate that ultrasonic assistance significantly reduces cutting forces by 20.09% and tool wear by promoting periodic tool–workpiece separation and improving chip evacuation. However, it increases surface roughness due to the formation of uniform micro-dimples, which may enhance tribological properties. Burr dimensions were primarily governed by feed-per-tooth, with higher feeds minimizing burr size. The study provides actionable insights into optimizing machining parameters for cutting Ti6Al4V, highlighting the trade-offs between force reduction, surface texture, and burr control. These findings contribute to advancing ultrasonic-assisted micro-milling for industrial applications, namely aerospace and biomedical applications requiring high precision and extended tool life. Full article

Wear inevitably occurs in ball screw assemblies after long-term operation, leading to a decline in transmission performance and machining accuracy. Therefore, the accurate identification of wear states is crucial. In this study, we propose a wear state identification method based on the surface profile of the ball screw. This method effectively overcomes the limitations of traditional experimental approaches that require frequent disassembly of the ball screw or rely on vibration and current signals, which are prone to external interference. Surface profile data covering the entire service life of the screw were obtained through performance degradation experiments. A hybrid feature set was constructed by extracting parameters such as roughness, peak-to-valley height, root mean square, recurrence rate, and fractal characteristics, and classification was performed using a genetic-algorithm-optimized support vector machine (GA-SVM). The experimental results demonstrate that the proposed method can accurately characterize wear evolution, achieving an average identification accuracy of 98.48% while maintaining robustness and effectively avoiding interference from extraneous signals. Full article

A chromium/amorphous carbon (Cr/(Cr/a-C)ml) nanostructured multilayer coating with a chromium sublayer was deposited on 42CrMo4 (1.7225,BDS EN ISO 683-2:2018), 100Cr6 (1.3505, BDS EN ISO 683-17:2024), and HS18-0-1 (1.3355, BDS EN ISO 4957:2018) alloy steels, selected for their use in contact-loaded components subjected to cyclic fatigue and intense wear. The coating was sputter deposited by MF pulsed magnetron sputtering under consistent process parameters. The resulting coating, approximately 1.8 μm thick, can significantly enhance the service life of these components. Adhesion was evaluated via the Daimler–Benz test, while coating homogeneity was confirmed through energy-dispersive spectroscopy, revealing a consistent chemical composition across sample surfaces. Raman spectroscopy indicated a high sp³/sp² ratio, confirming a dominant diamond-like carbon structure. Nanoindentation measurements verified the coating’s hardness, aligning with the observed structural properties. These results validate the process parameters for depositing a Cr/(Cr/a-C)ml coating on these alloy steels, achieving this study’s objectives. Full article

Using femtosecond laser processing technology, various textures with different morphologies were fabricated on titanium alloy surfaces to investigate the impact of texture morphologies and parameters on friction and wear performance. This study provides insights for improving the friction and wear performance of joint interfaces and extending the lifespan of artificial joints. Reciprocating friction and wear experiments were conducted on a UMT-3 multifunctional tribometer under oil-starved lubrication conditions. The effects of surface textures with different morphologies and parameters on friction and wear performance were examined. Under identical experimental conditions, laser micro-textured specimens demonstrated improved tribological performance compared to un-textured specimens. With the same dimple depth and coverage area, the optimal texture parameters varied among different morphologies, providing the best reduction in friction and wear resistance. This study systematically evaluated the effects of three different texture geometries (circular, elliptical, and groove) on tribological properties. The experimental results showed that under the same conditions, the elliptical texture performed the best in reducing the friction coefficient and improving load-bearing capacity. Compared to non-textured surfaces, the wear amount was reduced by 52.94%, the average friction coefficient was lowered by 20.51%, and the wear depth decreased by 75.09%. Laser micro-texturing on the surface can effectively enhance the anti-wear and friction-reducing properties of materials used in artificial joints. Full article

This study investigates the thermoelastic frictional contact and wear behavior during reciprocating sliding of a conductive cylindrical punch on a functionally graded piezoelectric material (FGPM)-coated half-plane. The thermo-electro-elastic properties of the coating vary continuously along the thickness direction according to arbitrary gradient functions, with thermal parameters being temperature-dependence. A theoretical framework for the coupled thermo-electro-elastic frictional contact problem is developed and solved using the finite element method. A sequential coupling approach is employed to integrate thermoelastic frictional contact with piezoelectric effects. Furthermore, wear on the coating surface is modeled using an improved Archard formulation, accounting for its impact on thermal sliding frictional contact characteristics. Numerical simulations examine the influence of wear, cycle number, friction coefficient, gradient index and gradient form on the coupled thermo-electro-elastic response of the FGPM coating structure. The numerical results demonstrate the gradient index and gradient form can effectively mitigate thermo-electrical contact-induced damage and reduce friction and wear in piezoelectric materials. Full article

This study investigates the interfacial behavior of four phosphate ester ionic liquids (ILs) with contrasting cation hydrophobicity under humid environments. Through tribological tests, surface analysis, and molecular dynamics simulations, we reveal how moisture absorption governs lubricant film organization at metal interfaces. Aromatic ILs (imidazolium/pyridinium cations) exhibit significant degradation in lubrication after moisture exposure, with friction coefficients increasing by 0.03–0.05 and wear volumes scaling with humidity. This deterioration arises from competitive water–cation adsorption, where hydrogen bonding disrupts Fe-cation coordination bonds and destabilizes the protective film. In contrast, aliphatic ILs (tetraalkylammonium/phosphonium cations) maintain robust tribological performance. Their alkyl chains spatially confine water to outer adsorption layers (>17 Å from the surface), preserving a stable core lubricating film (~14 Å thick). Molecular dynamics simulations confirm that water co-adsorbs with aromatic cations (RDF peak: 2.5 Å), weakening interfacial interactions, while aliphatic ILs minimize cation–water affinity (RDF peak: 4 Å). These findings establish cation hydrophobicity as a critical design parameter for humidity-resistant lubricants, providing fundamental insights into water-mediated interfacial phenomena in complex fluid systems. Full article

In the cold extrusion forming of thin-walled, specially shaped holes in aviation motor brush boxes, non-uniform metal flow can easily induce local stress concentrations on the punch, thereby accelerating wear. Reducing the punch wear and equivalent stress is therefore critical for ensuring the forming quality of such thin-walled features and extending the service life of the mold. In this study, a slender punch with a specially shaped cross-section was selected as the research object. The Deform-3D Ver 11.0 software, incorporating the Archard wear model, was employed to investigate the effects of five process parameters—extrusion speed, punch cone angle, punch transition filet, friction coefficient, and punch hardness—on the wear depth and equivalent stress of the punch during the compound extrusion process. A total of 25 orthogonal experimental groups were designed, and the simulation results were analyzed using the Taguchi method combined with range analysis to determine the optimal parameter combination. Subsequently, a multi-objective correlation analysis of the signal-to-noise ratios for wear depth and equivalent stress was conducted using the TOPSIS approach. The analysis revealed that the optimal combination of process parameters was an extrusion speed of 12 mm·s⁻¹, a punch cone angle of 50°, a punch transition filet radius of 1.8 mm, a friction coefficient of 0.12, and a punch hardness of 55 HRC. Compared with the initial process conditions, the integrated application of the Taguchi–TOPSIS method reduced the punch wear depth and equivalent stress by 21.68% and 42.58%, respectively. Verification through actual production confirmed that the wear conditions of the primary worn areas were in good agreement with on-site production observations. Full article

In this study, shot blasting was employed to enhance the wear resistance and impact toughness of SCMnH11 high-manganese steel. The steel was first fabricated via vacuum casting, followed by forging and water-toughening treatment. Subsequently, the steel was cut to the required dimensions using wire electrical discharge machining before the final shot blasting was performed. The influence of shot blasting duration on the microstructure and mechanical properties was investigated. Shot blasting introduced compressive residual stress and dislocations, resulting in the formation of numerous low-angle grain boundaries. As the shot blasting time increased, the surface grains were progressively refined. The surface hardness increased rapidly from an initial value of approximately 250 HV, reaching a maximum of 643 HV. After 60 min of shot blasting, the thickness of the surface hardened layer reached 600 µm; however, the surface hardness exhibited a trend of first increasing and then decreasing. In contrast, the wear resistance showed the opposite trend. Additionally, the dominant surface wear mechanism transitioned from adhesive wear in the heat-treated sample to abrasive wear in the shot-blasted samples. Compared to the heat-treated sample, the impact toughness of the samples subjected to 5 min and 60 min shot blasting was significantly enhanced. Correspondingly, the fracture mechanism shifted from predominantly ductile fracture to a mixed mode of ductile and cleavage fracture. In summary, shot blasting can effectively enhance the wear resistance and impact resistance of SCMnH11 steel. However, the selection of shot blasting duration is critical. Appropriate parameters can balance work hardening, compressive stress, and surface microcracks, thereby enabling the material to achieve an optimal combination of wear resistance and impact resistance. Full article

Erosion wear is a primary factor in material failure and is widely observed in hydropower, petroleum, aerospace, and other industrial fields. It is evident from the findings of numerous research studies that both the characteristics of particles and the fluid dynamic parameters are significantly associated with the occurrence of erosion damage. However, there has been a paucity of research into the correlation between the mechanical properties of materials and their erosion wear behaviour. This review methodically summarises the latest understanding of erosion wear mechanisms and influencing factors, with a specific focus on how the mechanical properties of materials regulate erosion processes. Furthermore, it provides a concise overview of erosion mechanisms and fluid dynamic factors, while undertaking a critical evaluation of the discrepancies observed among various erosion wear rate prediction models. The overarching objective of this research is to enhance mechanistic comprehension, facilitate the integration of prediction models with material property databases, and furnish a theoretical foundation for the design of erosion-resistant materials and the development of industrial protection strategies. Full article

The texture of asphalt pavement wears down over time due to traffic polishing, which leads to polished pavement surfaces with lower skid resistance. Three-dimensional (3D) texture parameters can be used to describe the evolution of pavement texture and establish predictive models for skid resistance. In this study, a high-resolution 3D laser scanner and a pendulum friction tester were used to collect 3D texture data and the corresponding friction values of dense-graded asphalt pavement over a period of four years. Fourier transformer and Butterworth filters were applied to decompose the 3D texture data into micro-texture and macro-texture components. Twenty different 3D texture parameters from five categories (height, spatial, hybrid, functional, and feature parameters) were calculated from pavement micro- and macro-textures and optimized using correlation methods to derive an independent set of texture parameters. The performance of a multiple linear regression model and neural network predictive model for predicting skid resistance via selected texture parameters was compared through training and testing. The results indicate that pavement micro-texture contributes more significantly to skid resistance than macro-texture, and neural network models can effectively predict the temporal evolution of skid resistance based on texture data. The neural network model achieves R² values of 0.92 and 0.89 on the training and testing sets, respectively, with RMSE values of 3.37 and 5.45, significantly outperforming the multiple linear regression model (R² = 0.50). Full article

Harsh working environments and excessive usage frequency cause wear, fatigue, and corrosion failure in metallic components in high-end agricultural machinery and equipment. Overall replacements of valuable metallic components could result in high overhaul costs and material waste. Therefore, remanufacturing these local areas is an effective way to put damaged components back into service, thus maximizing the value of the remaining materials. Laser cladding (LC) technology utilizes high-energy, high-density laser beams to create cladding layers with specialized properties such as wear and corrosion resistance on the surfaces of damaged metallic components. This work provides a comprehensive analysis of pre-processing, processing, and post-processing in relation to laser cladding remanufacturing (LCR) of metallic components. The review examines the LC process, including material systems (Fe-, Ni-, and Co-based alloys and composites), process optimization, and path planning. The relationship between material composition, process parameters, microstructure evolution, and resultant properties (wear, corrosion, and fatigue) is emphasized. Finally, challenges and future trends faced in this process are introduced in detail. The discussed topics provide some important insights on high-quality and efficient remanufacturing of metallic components in high-end agricultural machinery and equipment. Full article