Search Results (1,141)

To address the practical requirements for in situ equipment restoration, this study investigates a portable and cost-effective approach for the localized repair of SAE 10SAE 1045 components using a 1Cr13 martensitic stainless steel coating prepared via an arc-based additive manufacturing (WAAM) process. The microstructural evolution and tribological response of the layers were analyzed, with a focus on the effects of discrete thermal cycling and controlled solidification inherent to portable arc equipment. The WAAM process produced a refined martensitic matrix with a microhardness of 551.94 HV0.2, which is 2.26 times that of the substrate. Under dry sliding conditions, the 1Cr13 coating exhibited a lower friction coefficient and a reduced wear volume compared to the untreated SAE 1045, primarily through the mitigation of severe plastic deformation. This additive route provides a millimeter-scale reinforcement layer with metallurgical integrity suitable for heavy-duty service, aiming to offer a practical reference for the low-cost, on-site restoration of industrial components. Full article

High-entropy alloy (HEA) coatings are widely recognized for their excellent hardness and wear resistance. Heterogeneous cabled wire welding (HCWW) combined with gas metal arc welding (GMAW) has emerged as an efficient approach for fabricating HEA coatings; however, severe arc instability inherent to HCWW often deteriorates coating quality. In this study, the effects of axial magnetic fields (AMFs) with different orientations on the HCWW–GMAW process were systematically investigated. High-speed imaging revealed that the HCWW arc without magnetic assistance exhibits pronounced instability, characterized by asymmetric morphology and rotational behavior. The application of AMFs significantly altered arc dynamics. An upward axial magnetic field (N-AMF, 2 mT) effectively suppressed arc rotation, resulting in a stable bell-shaped arc and more uniform heat input, whereas a downward axial magnetic field (S-AMF) caused arc contraction and promoted dendrite coarsening. Consequently, the N-AMF condition led to a refined and homogeneous microstructure, yielding a high microhardness of 825 ± 15 HV. Tribological tests demonstrated that the wear rate of the N-AMF-assisted coating was reduced by 55% compared with that produced by conventional GMAW. These results highlight that magnetic-field-induced arc stabilization plays a critical role in achieving high-performance HEA surface coatings. Full article

In order to provide clinically significant evidence on the long-term functional performance of CAD/CAM provisional materials, especially 3D-printed and milled resins, accurate tribologically in vitro wear tests that integrate wear parameters and surface topography analysis are necessary. The goal of the study was to assess the wear resistance of several CAM-obtained dental crown materials and the relationship between wear and the manufacturing process, distinctive postprocessing, microhardness, microroughness, and surface topography. A standardized ball-on-flat tribological protocol was applied to (n = 70) CAD/CAM-fabricated PMMA specimens (four 3D-printed groups with distinct post-processing protocols (Optiprint) and three milled materials (TelioCAD, Shaded PMMA, Copra Temp Symphony)) to quantify wear parameters micro- and nanoroughness (Ra, Rz, Sa, Sy), and Vickers microhardness, followed by comprehensive statistical analysis (t-tests, Pearson correlations) to elucidate material- and process-dependent differences in wear behaviour. Nanoroughness was carried using atomic force microscopy evaluation. Wear testing showed that most materials, particularly the 3D-printed groups, developed limited wear, whereas the milled materials evolved toward groove-dominated wear topographies. Wear statistics showed that the printed resins consistently had an advantage, meaning that the degree and rate of wear are significantly influenced by the manufacturing process. Hardness has a central role in governing the wear performance of interim resin materials, while nanoroughness acts as a secondary factor. Optimised post-processing of printed materials, particularly a prolonged post-curing period, yields a beneficial combination of low wear and specific topography, thereby providing a significant clinical advantage. Full article

Polyether ether ketone (PEEK) is a high-performance thermoplastic with potential applications in aerospace, automotive, and biomedical components, owing to its exceptional specific strength, thermal stability, and biocompatibility. However, its moderate hardness and limited wear resistance in dry sliding severely constrain its use in highly loaded tribological contacts. In this study, PEEK-based reinforced hybrid composites were produced utilizing a powder metallurgy technique, with reinforcement fractions of 10 wt.% graphite (Gr), boron (B), hydroxyapatite (HAp), and zirconium (Zr). The processing sequence included homogeneous wet-mixing, uniaxial cold compaction at pressures of 10–30 MPa, and sintering at 250–300 °C. The composition and microstructures were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Mechanical and tribological performances were assessed by Vickers microhardness, uniaxial compression and dry sliding wear tests. The best-performing Gr-B hybrid composite increased hardness by 240% and compressive strength by 175% compared with unreinforced PEEK. Tribologically, boron-containing PEEK demonstrated up to a 34.7% reduction in the coefficient of friction and approximately a 90% drop in wear-induced mass loss compared with unreinforced PEEK. The resulting Gr-B-reinforced PEEK hybrids are excellent choices for demanding load-bearing and tribological components like aerospace bushings, automotive sliding elements, spinal cages, and orthopedic fixation devices in biomedical applications because of their balanced combination of high hardness, superior wear resistance, and high compressive strength. Full article

Deep-sea gear transmission systems encounter critical lubrication challenges arising from the synergistic coupling of extreme hydrostatic pressure and cryogenic temperatures. These environmental stressors induce exponential viscosity escalation in lubricants, precipitating severe fluidity degradation, elevated startup resistance, and lubrication starvation. Concurrently, seawater intrusion triggers lubricant emulsification, additive deactivation, and electrochemical corrosion at meshing interfaces, collectively escalating the risk of catastrophic lubrication failure and compromising long-term operational reliability. This study systematically elucidates the lubrication degradation mechanisms inherent to deep-sea environments and proposes targeted mitigation strategies. Through comprehensive characterization of deep-sea environmental parameters and their impact on lubricant rheological behavior, we critically evaluate the applicability and inherent limitations of conventional Thermal Elasto-Hydrodynamic Lubrication (TEHL) theory under extreme conditions. Our analysis reveals that established TEHL frameworks necessitate substantial modification to accurately capture pressure-viscosity-temperature coupling phenomena and seawater contamination kinetics. Meshing interface texturing, as an effective anti-friction and wear-mitigation strategy, is investigated to delineate its mechanistic pathways for enhancing lubricant film formation and tribological performance under starved lubrication regimes. Key findings demonstrate that optimized micro-texture architectures can effectively compensate for viscosity-induced fluidity deficits and attenuate the deleterious effects of seawater ingress. Critical knowledge gaps are identified, and future research trajectories are charted: (i) multiphysics coupling models integrating thermo-hydrodynamic, chemo-physical, and mechanical degradation processes; (ii) synergistic texture-coating design paradigms; (iii) high-pressure low-temperature experimental validation protocols; and (iv) engineering implementation frameworks for deep-sea gear transmission systems. This review establishes theoretical foundations and provides technical guidelines for robust lubrication design and long-term operational stability of deep-sea transmission equipment. Full article

Recent innovations with the aid of nanotechnology are more frequently seen in the industrial sectors. Lubricants are a high-end commodity resource used in many manufacturing processes; unfortunately, most of these lubricants are petroleum-based, which come with certain drawbacks, such as environmental aspects, handling issues and high costs. With the incorporation of nanostructures within fluids and lubricants, novel material alternatives are replacing conventional lubrication systems, maintaining the required thermophysical and tribological characteristics. This research provides an analysis of vegetable lubricant, castor oil (CO), and the effects of the incorporation of WS₂ nanofiller at diverse filler fractions. A TEMPOS thermal analyzer device and a four-ball tribotester are used for the analysis of thermal conductivity and tribological assessments, respectively. Results showed the enhancement of thermal conductivity as the filler concentration and the evaluation temperature of the nanolubricants increased. The best thermal conductivity improvement was 27%, at 60 °C with merely 0.20 wt.% of nanofillers. For tribological performance, a decrease of 6% in the coefficient of friction (COF) and 31% in the wear scar diameter (WSD) was observed at 0.10 wt.% and 0.20 wt.%, respectively. Adhesion of the nanostructures to the steel surfaces creates a protective layer, preventing direct contact of the friction pairs. These results are an outcome of applied theoretical concepts such as Brownian motion and nano-layering of the lubricant–nanostructure interface. Full article

Molybdenum disulfide (MoS₂)-based composite systems are widely used as solid lubricating coatings. However, further optimization towards lower friction and higher wear resistance remains necessary to meet the extreme operating conditions and high reliability requirements of next-generation aerospace equipment. This study investigated the tribological performance of MoS₂/epoxy composite coatings by comparing the effects of individual and combined additions of nano nickel (Ni) and magnesium silicate hydroxide (MSH). The coating preparation process adopted in this study is the bonding method. Experimental results showed that, under a load of 2 N and a rotational speed of 500 r/min, the coating containing 0.3 g Ni and 0.1 g MSH (labeled W03Ni01MSH) achieved a 22% reduction in wear scar width compared to the coating with only Ni, demonstrating a distinct synergistic effect. This is attributed to the complementary roles of the two additives: Ni promotes the formation of flaky wear debris, facilitating rapid formation and stabilization of a transfer film, thereby reducing friction; MSH enhances the load carrying capacity of the coating and suppresses wear propagation, thereby improving wear resistance. Furthermore, this composite coating exhibited optimal performance under the conditions of 500 r/min and 2 N. The results of this study significantly improved the friction-reducing and wear-resistant properties of the MoS₂/epoxy composite coating. This provides a new strategy for the formulation design of high-performance solid lubricating coatings. Full article

In view of the potential fretting wear issues of Laser Metal Deposition (LMD) In718 in engineering applications, this paper investigates the fretting wear behavior of LMD In718 alloy subjected to two different heat treatment processes: homogenized Solution-Treated and Aged (STA) and direct-aged only. This was conducted utilizing a newly designed fretting wear apparatus to enable real-time dynamic monitoring of the contact interface and maintain uniform normal force distribution. Furthermore, to provide a more comprehensive understanding of how different heat treatments influence the fretting wear performance of LMD In718, this study systematically evaluates their distinct tribological responses and underlying wear mechanisms. The wear resistance of the material was predicted by analyzing the proportion of the main strengthening phase γ″ in samples with different heat treatments using microstructural characterization methods. Wear resistance tests were conducted under ambient conditions. The results show that the homogenized STA sample has a specific wear rate of 1.375 × 10⁻⁷ mm³/(N∙m), while the direct-aged sample has a wear rate of 1.550 × 10⁻⁷ mm³/(N∙m). The direct-aged sample exhibited severe fatigue spalling accompanied by adhesive and abrasive wear, with numerous subsurface cracks. The homogenized STA sample demonstrated a combined mechanism of oxidative wear and localized abrasive wear. Full article

This study analyses the effect of electrolytic plasma treatment on improving the wear resistance of 30CrMnSi steel used under conditions of high abrasive and impact-abrasive loads. The samples were processed using various technological regimes, namely electrolytic plasma quenching, nitriding, nitrocarburising, and carburising. A range of analytical methods were employed to comprehensively characterise the structure, phase composition, and mechanical properties, including SEM/EDS, XRD, and microhardness testing. The tribological properties of the materials were evaluated using a TRB³ tribometer, and abrasive and impact-abrasive wear tests were performed in accordance with GOST 23.208–79 and GOST 23.207–79 standards. The results show that electrolytic plasma treatment leads to the formation of diffusion layers with a thickness of 50–150 μm, accompanied by the formation of carbide, nitride, and carbonitride phases (Fe₄C, Fe₇C₃, Fe₄N, Fe₂N, Fe₃(CN)). This process results in a significant increase in surface hardness (up to 610–930 HV) and improved wear resistance. The study indicates that electrolytic plasma nitrocarburising provides a favourable combination of hardness and tribological behaviour, leading to a low friction coefficient (0.25–0.35) and enhanced resistance to abrasive and impact-abrasive wear. The obtained results demonstrate the potential of this technology for improving the performance of components made of 30CrMnSi steel operating under severe wear conditions. Full article

The study aims to strengthen cylindrical liners by plasma electrolytic oxidation (PEO) and to determine the optimal processing parameters for forming wear-resistant coatings. The results of laboratory experiments were transferred to practical application for liner strengthening, followed by testing coatings formed directly on real components. PEO was applied to cylindrical sleeves made of eutectic aluminum–silicon alloy EN AC-48000 to form mechanically strong and wear-resistant oxide coatings. The coating had a two-layer structure: a dense inner barrier layer and a porous outer layer. The effect of SiO₂ (~20 nm) and Al₂O₃ (~30 nm) nanoparticles in the electrolyte on the morphology, phase composition, microhardness and tribological characteristics of the coatings was evaluated. The optimal PEO parameters were determined as 325 V, duty cycle 25%, processing time 12 min, average current density 1.4 A·dm⁻², and concentration of Al₂O₃ + SiO₂ (5 + 5 g L⁻¹). Under these conditions, the coating achieved a maximum microhardness of 259 HV, a low coefficient of friction of ~0.50 and a wear rate of 0.81 × 10⁻⁴ mm³·N⁻¹·m⁻¹. X-ray diffraction analysis confirmed the formation of γ-Al₂O₃ without changing the silicon phase. The results provide quantitative data on the effects of nanoparticles and PEO parameters on coating properties, which is important for the development of long-life part surfaces. The increased microhardness and wear resistance are attributed to the formation of the ceramic γ-Al₂O₃ phase and the densification of the porous structure due to the incorporation of Al₂O₃ and SiO₂ nanoparticles, which reduce defect density and limit the adhesive–abrasive wear mechanism. Full article

This study systematically investigates a novel two-step approach to enhance the tribological performance of ultra-high molecular weight polyethylene (UHMWPE) by combining biaxial stretching with a subsequent hot pressing treatment. The significance of this work lies in developing a continuous, high-efficiency process that allows for decoupled control of bulk mechanical properties and surface tribological characteristics. The material’s evolution was comprehensively characterized using Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), tensile testing, and a Taber Abraser. Results show that biaxial stretching significantly enhanced the film’s bulk mechanical strength and thermal stability, creating a wider processing window for subsequent surface treatment. A subsequent hot pressing step was then applied to refine the surface characteristics, yielding an optimal wear rate of 0.002 g/1000 cycles and a kinetic coefficient of friction (µk) of 0.106. Achieving such a concurrent optimization of high wear resistance and low friction is crucial in materials processing. The study demonstrates that the synergistic effect of biaxial orientation and hot pressing-induced crystal perfection provides a powerful and previously unreported pathway to achieving a superior balance of low wear and low friction in UHMWPE. Full article

Conventional tribological materials such as metals, ceramics, and synthetic polymers demand energy-intensive processing and create end-of-life waste. This motivates the search for more sustainable alternatives. Recent research demonstrates that agricultural residues, industrial by-products, post-consumer waste, and recycled polymers can be engineered into tribological systems that provide competitive wear resistance, stable friction, and multifunctional benefits, including thermal dissipation and vibration damping. This review summarizes progress across these material categories, highlighting how fillers like rice husk ash, fly ash, tire-derived carbon black, and reprocessed plastics transition from low-value waste into high-performance tribomaterials. System-level strategies such as interface engineering, hybrid reinforcement, and advanced processing are essential for overcoming material variability and achieving reliable tribological performance. In parallel, optimization approaches, including predictive modeling and smart material design, are increasingly enabling improved consistency, reproducibility, and scalability. Applications in automotive braking systems, recycled carbon black composites, acoustic damping structures, coatings, and reinforced polymers confirm the industrial viability of waste-derived materials. While challenges remain in feedstock variability, standardization, and long-term durability, these developments point to waste-based tribology as a practical pathway toward circular economy solutions that unite sustainability with engineering performance. Full article

Gear systems operate under high mechanical and tribological loads, making their surfaces vulnerable to wear and fatigue. Improving surface durability requires finishing processes that improve near-surface properties and extend service life. Since machine hammer peening (MHP) offers such potential, this study investigates its influence on the performance of case-hardened spur gears and evaluates its suitability as an alternative to shot peening as a conventional finishing method. Analog specimens with simplified geometries were treated using various MHP parameters to identify effective process settings. These optimized settings were then applied to real spur gears to assess performance under practical conditions. The experiments showed that MHP can significantly modify surface integrity, achieving surface roughness reductions of up to 55%, surface hardness increases of up to 30%, and compressive residual stresses exceeding −1400 MPa with stability to depths of 200 µm. These modifications resulted in improved wear and fatigue performance, with increases in load cycle number in the tooth flank up to 99% and an increase in load amplitude in the tooth root of more than 5%. For comparison, specimens were also treated with shot peening. Although MHP induced stronger surface integrity modifications, shot peening achieved higher overall load-carrying capacity because several critical areas could not be fully accessed by MHP, limiting its effectiveness. Overall, MHP shows promise as a finishing process, but its full potential depends on overcoming accessibility limitations in complex gear geometries. Full article

Nickel foam filtration layers used in sand control screens for petroleum extraction often suffer from insufficient mechanical strength and poor corrosion resistance and wear resistance. In this work, a two-stage electroplating strategy using the same metal was employed to construct hierarchical nickel coatings on nickel foam substrates. The effects of key process parameters, including electroplating time, temperature, and pretreatment, on the microstructure, mechanical properties, electrochemical corrosion behavior, and tribological performance of the coatings were systematically investigated. Electroplating time was found to directly regulate grain size and coating uniformity, while electroplating temperature significantly influenced nickel deposition behavior and electrolyte stability. In addition, UV pretreatment markedly improved the brightness and homogeneity of the deposited layers. Under optimized conditions (UV pretreatment for 10 min, electroplating at 60 °C for 8 min), a dense and uniform nickel coating with a well-ordered crystalline structure was obtained, leading to significantly enhanced hardness, wear resistance, and corrosion resistance. This study presents a practical and highly reliable approach for fabricating high-performance nickel-based coatings on nickel foam filter layers. Anticipated for application in the oil extraction industry, this method is set to enhance the performance of foam metal sand control layers. Full article

Carbon Fiber-Reinforced Polymer (CFRP) composites represent a transformative class of structural materials, combining low density, high specific strength, and excellent fatigue resistance. This review provides a comprehensive overview of CFRPs, addressing their structure, manufacturing routes, mechanical performance, and functional behavior, with particular emphasis on damage tolerance, tribological properties, and environmental durability. The discussion begins with the classification and morphology of carbon fibers, highlighting their influence on composite anisotropy and interlaminar behavior. The effects of impact loading, delamination, and environmental conditioning on residual strength and fatigue life are then examined, with reference to established evaluation methods such as ASTM D7136 and compression-after-impact (CAI) testing. From a tribological perspective, the incorporation of nanoscale additives, such as graphite nanoplatelets and TiO₂ nanoparticles, and their contribution to enhancing wear resistance by promoting the formation of stable tribofilms, is explored. Advances in processing techniques, including low-pressure curing and improved resin systems, are also discussed for their roles in enhancing manufacturability and energy efficiency. Overall, the review underscores that optimal CFRP performance is achieved through the synergistic integration of fiber architecture, matrix design, and precise processing control, while future progress in nanomodification, recycling, and sustainable curing technologies is expected to further expand CFRP applications in the aerospace, automotive, and high-performance engineering sectors. Full article