Tribology Letters最新文献

{"title":"Liquid-Phase Deposition of Carbonaceous Polymeric Films from Cycloalkane Additives on Steel Surfaces","authors":"Zaid A. Al Hassan,&nbsp;Harry Wise,&nbsp;Tobias Martin,&nbsp;Stephen Berkebile,&nbsp;Q. Jane Wang,&nbsp;Yip-Wah Chung","doi":"10.1007/s11249-026-02151-y","DOIUrl":"10.1007/s11249-026-02151-y","url":null,"abstract":"<div><p>This study investigates the liquid-phase deposition (LPD) of carbonaceous tribopolymeric films from cyclopropane-carboxylic acid (CPCa), an additive dissolved in polyalphaolefins, under boundary-lubricated sliding conditions. In this approach, the lubricant acts as a carrier for a reactive chemical precursor, while the sliding contact functions as a tribochemical reactor that drives in-situ film formation. Ball-on-disk sliding experiments were conducted using n-dodecane containing 5 wt.% CPCa on AISI 52100 and D2 steels of identical hardness but different chromium content. The addition of CPCa reduced wear coefficients by approximately an order of magnitude on both steels. Raman spectroscopy confirmed the formation of disordered, sp²-rich carbon tribopolymeric films that were soluble in dichloromethane, distinguishing them from conventional PVD/CVD-deposited amorphous carbon coatings. Confocal profilometry revealed heterogeneous tribofilm thicknesses of ~ 100 nm within the contact. Upon CPCa removal from the lubricant, these tribofilms acted as sacrificial, wear-protective layers, with substantially greater durability on chromium-rich D2 steel than on 52100 steels. These results demonstrate that CPCa-derived tribopolymeric films can be formed rapidly by liquid-phase deposition and provide effective wear protection, highlighting tribocatalysis with appropriate chemical precursors as a promising pathway for replenishable, in-situ carbon coatings.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-026-02151-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147830105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of Grease Rheology at Extremely Large Shear Rates and its Correlation with Tribological Behavior in the Isoviscous-Rigid Regime","authors":"Mohd. Mubashshir,&nbsp;Sagar B. Kale,&nbsp;Asima Shaukat","doi":"10.1007/s11249-026-02146-9","DOIUrl":"10.1007/s11249-026-02146-9","url":null,"abstract":"<div><p>Lubricating greases exhibit far more complex tribological behavior than lubricating oils due to their biphasic composition and non-Newtonian rheology. In the hydrodynamic regime, where a full grease film separates the moving surfaces, the tribological response is governed by the rheological dynamics of grease within the contact zone. However, these dynamics are hard to measure directly since the shear rates inside tribocontacts far exceed those accessible on conventional rheometers. To address this, a rheological superposition technique is employed to extend grease flow curves to such extremely high shear rates. The friction‒speed curves for all the grease samples are generated using a ball-on-disc tribometer operating under the isoviscous-rigid regime (low contact pressure and constant temperature). Simultaneously, the variation of electrical contact resistance with speed is recorded. The effective viscosity of each sample in the hydrodynamic lubrication regime is estimated by superposing the hydrodynamic portion of the friction curve onto a master curve. Remarkably, the effective viscosities agree closely with the infinite shear viscosities determined from the superposition method. At high speeds, however, deviations emerge: the effective viscosity falls below the infinite-shear viscosity, indicating a departure from classical hydrodynamic behavior. To our knowledge, this is the first report of a quantitative correlation between grease hydrodynamic lubrication and high-shear rheology. In the boundary regime, the base oil properties, particularly its molecular structure and physicochemical interactions with the contact surface, as well as the morphology and concentration of the thickener, govern the film formation and friction response. These insights offer guidance for formulating greases with tailored properties to optimize lubrication performance.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147829328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Trace Moisture on the Tribological Behavior of PTFE/PPS Composite in High-Purity Hydrogen Atmosphere","authors":"Yue He,&nbsp;Hironori Shinmori,&nbsp;Takehiro Morita,&nbsp;Kanao Fukuda,&nbsp;Yoshinori Sawae","doi":"10.1007/s11249-026-02148-7","DOIUrl":"10.1007/s11249-026-02148-7","url":null,"abstract":"<div><p>High-purity hydrogen is essential in fuel cell vehicles (FCVs), which require strict control of impurities, including residual moisture content. Therefore, it is imperative to thoroughly investigate the influence of trace moisture on the friction and wear behaviors of tribomaterials. In this study, the friction and wear behaviors of polytetrafluoroethylene (PTFE) composites containing 20% of polyphenylene sulfide (PPS) in a high-purity hydrogen gas environment were investigated under various contact pressures, sliding speeds, and trace-moisture contents at the parts per million (ppm) level. A pin-on-disk tribometer installed in a high-vacuum chamber was used for the tests, and the disk material was SUS440C stainless steel. The results revealed that the trace-moisture content significantly affected the wear rates of the PTFE/PPS composites. At a moisture content of ~ 20 ppm, the wear rate was reduced to one-tenth the wear rate at a low-moisture content of ~ 1 ppm. This reduction is attributed to the effective formation of a PTFE-based transfer film supported by interfacial tribochemical reactions, accompanied by the formation of metal fluorides. Conversely, at a moisture content of 1 ppm, insufficient stabilization of the PTFE transfer film leads to the adhesion of PPS to the counterface, resulting in increased wear. Despite the variations in wear rates, the friction coefficient remained relatively invariant, regardless of the moisture level. These findings highlight that even trace amounts of moisture, often neglected owing to the assumption of hydrogen purity, can critically affect tribological performance. Without understanding this moisture effect, severe wear may occur unexpectedly, which poses a risk for FCV-related hydrogen systems.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Ambient-Degraded MXene on Rheological and Tribological Behaviour of Synthetic Multigrade Oil","authors":"Nowduru Ravikiran,&nbsp;Swati Singh,&nbsp;Phani Chalapaka,&nbsp;Sanjay R. Dhage,&nbsp;P. K. Jain","doi":"10.1007/s11249-026-02140-1","DOIUrl":"10.1007/s11249-026-02140-1","url":null,"abstract":"<div><p>While two-dimensional Ti₃C₂T_<i>x</i> MXenes demonstrate exceptional tribological potential, their susceptibility to ambient oxidation poses a critical barrier to commercial deployment. The current state of the art predominantly focuses on synthesis ing new MXenes and studying their tribological properties; however, the tribological performance of the inevitably degraded Ti₃C₂T_<i>x</i> MXenes, specifically their interaction (synergism/antagonism) with commercial lubricant additives, remains largely unexplored. This study presents the first systematic evaluation of ambiently degraded Ti₃C₂T_<i>x</i> MXene (aged for 8 weeks) as an additive in commercial 10W30 engine oil. The structural evolution was characterised by oxidation-induced sheet fragmentation and lattice collapse (monitored via XRD, Raman, and SEM), followed by rheological and tribological behaviour across variable concentrations (0.01–0.1 wt.%). Tribological assessments revealed a counterintuitive, non-monotonic concentration dependence. At sub-critical loadings (0.01–0.05 wt.%), the degraded Ti₃C₂T_<i>x</i> MXene nanosheets acted as abrasive third-body agents, exacerbating friction and wear. Conversely, a critical concentration of 0.1 wt.% triggered a mechanistic shift, where the accumulation of degraded Ti₃C₂T_<i>x</i> MXene facilitated the formation of a protective tribofilm, significantly reducing the coefficient of friction and wear despite high sedimentation rates. These findings challenge the paradigm that only pristine nanomaterials are effective, highlighting a complex trade-off between dispersion stability and tribofilm formation. This work provides essential guidelines for defining the functional endurance of Ti₃C₂T_<i>x</i> MXene-based lubricants in real-world engineering environments.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An extended Griffith friction model for the transition to slip in the contact of graded-material spheres","authors":"Shi-Wen Chen,&nbsp;Gang-Feng Wang,&nbsp;Michele Ciavarella","doi":"10.1007/s11249-026-02134-z","DOIUrl":"10.1007/s11249-026-02134-z","url":null,"abstract":"<div><p>In the present paper, we study the role of gradient in the material properties of contacting bodies in the difference between static and kinetic friction for a Hertzian geometry, according to the theory of \"Griffith friction\", for which the transition from stick to slip occurs as an elastic instability. We use the term \"Griffith friction\" to suggest an energy balance approach in mode II to derive stable and unstable equilibrium configurations, where in particular macroscopic sliding can occur by a global elastic instability, analogous to a Griffith crack which doesn’t arrest after reaching a critical size. The most important conclusion are that static friction coefficient: (i) is increased with harder surface; (ii) is increased for small normal loads and tends to infinity in the limit of zero load. These conclusions hold both in the case of a constant frictional fracture energy or a pressure-dependent frictional fracture energy at the interface.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-026-02134-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147797105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inlet Pressure and Shear Stress of Elliptical Elastohydrodynamic Contacts","authors":"Wassim Habchi,&nbsp;Scott Bair","doi":"10.1007/s11249-026-02141-0","DOIUrl":"10.1007/s11249-026-02141-0","url":null,"abstract":"<div><p>The inlet pressure in elastohydrodynamic lubrication corresponds to the maximum pressure within the contact inlet, beyond which hydrodynamic effects no longer contribute to film build-up. This quantity is important for properly defining lubricant pressure–viscosity coefficients. The associated inlet shear stress, in turn, is a useful indicator of the validity of the Newtonian assumption. Only recently were inlet pressure and shear stress quantified by the authors for line and circular contacts through numerical simulations, revealing pressures in the range of 50–185 MPa and shear stresses up to 3 MPa, depending on operating conditions. The present work extends this quantification process to wide and slender elliptical contacts. Compared to circular contacts under similar conditions, slender contacts exhibit higher inlet pressures, reaching up to 350 MPa, and shear stresses up to 7 MPa, whereas wide contacts display lower values. The more contact ellipticity deviates from unity (i.e., circular contact), the more pronounced the deviations in both inlet pressure and the corresponding shear stress become, relative to circular contacts. Finally, analytical formulae are provided for evaluating inlet pressure and shear stress as functions of operating conditions, material properties, and contact ellipticity.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Femtosecond Laser-Texturing of a Novel Micro-Texture with Solid Lubricant Additives for Friction Reduction","authors":"Roland Bejjani,&nbsp;Marc Chamoun","doi":"10.1007/s11249-026-02142-z","DOIUrl":"10.1007/s11249-026-02142-z","url":null,"abstract":"<div><p>Femtosecond laser micro-texturing of surfaces has been established as an important technology to reduce frictional losses in lubricated sliding systems. This work differs from previous studies by investigating an optimized micro-texture designed for enhanced hydrodynamic pressure generation combined with graphene and MoS₂ additives to analyze their synergetic friction-reduction mechanism. First, computational fluid dynamics simulations were used to analyze the hydrodynamic pressure build-up and lubricant flow behavior of the micro-texture and film. The simulated lubricant flow pathways also provided insight into the transport of the solid lubricant particles throughout the micro-texture and lubricant film, representing another distinctive aspect of this study. A femtosecond laser was then used to precisely engrave the micro-textures, with optimized process parameters to achieve sharply defined edges, while avoiding thermal damage. Finally, the tribological behavior of the micro-texture was experimentally evaluated using a novel tribometer under different contact pressures, sliding speeds, and solid lubricant additives. When combined with solid lubricant additives, a synergetic friction-reduction effect was observed, attributed to the combined effects of the increase in the film thickness due to hydrodynamic pressure generation, solid lubricant particle retention within the texture and transport throughout the film, forming low-shear tribo-films of solid lubricant additives at the contact interface.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lubrication Performance of Gas–Liquid Two-Phase through Low-Surface-Energy Textures with Bubble Inducing and Stabilizing","authors":"Lixia Xue,&nbsp;Yuanyuan Jiang,&nbsp;Jiujun Xu,&nbsp;Zhijun Yan,&nbsp;Yan Shen","doi":"10.1007/s11249-026-02135-y","DOIUrl":"10.1007/s11249-026-02135-y","url":null,"abstract":"<div><p>Under fluid lubrication conditions, utilizing textures to generate stable gas–liquid two-phase lubrication has emerged as a promising drag reduction approach. A textured surface with both low-surface-energy and bubble induced-stored capability was fabricated by a “one-step” laser method that integrates surface functional layer and texture geometry. By optimizing texture distribution, a stable gas–liquid two-phase layer formed between tribology pairs. Compared with non-texture samples, the texture reduced the maximum friction by up to 61.3%. Furthermore, a dynamic two-phase lubrication model was established through simulation, accounting for oil film thickness variation and clarifying how textures affect fluid pressure distribution and gas entrapment. This work provides fundamental support for the design of friction-reducing morphologies on tribo-pairs, offering an effective solution to mitigate energy dissipation in mechanical friction systems.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Friction Dynamics of Denim Fabrics with Washing or Polishing Treatment","authors":"Rintaro Kawakami,&nbsp;Ken Miyata,&nbsp;Syuji Kobayashi,&nbsp;Mitsumasa Kimata,&nbsp;Yoshimune Nonomura","doi":"10.1007/s11249-026-02143-y","DOIUrl":"10.1007/s11249-026-02143-y","url":null,"abstract":"<div><p>The friction properties between human skin and fabrics are important because they affect the latter’s attractiveness. In this study, we evaluated the friction force on three denim fabrics and cashmere, wool, and cotton fabrics using a sinusoidal motion friction evaluation system that replicates human motion. We analyzed the effects of physical properties (elastic modulus, surface roughness, and thickness) on friction properties. Washing treatment for starch removal reduced the Young’s modulus from 36.6 ± 3.8 kPa to 16.1 ± 0.3 kPa and increased the friction coefficient from 0.28 ± 0.01 to 0.30 ± 0.01. After the fabric was polished, the Young’s modulus decreased to 8.3 ± 1.0 kPa and the friction coefficient increased to 0.33 ± 0.01. The friction coefficients of the denim, cashmere, wool, and cotton fabrics increased as their Young’s modulus decreased. Therefore, washing and polishing treatments soften denim, increase the real contact area between the contact probe and the fibers, and increase friction resistance. These findings are useful for controlling tactile textures and developing more attractive denim fabrics.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polymer Brush-Enhanced Extraction and Spreading of Oil from Lubricating Greases","authors":"Luciana Buonaiuto,&nbsp;Vincent Siekman,&nbsp;Sander Reuvekamp,&nbsp;Piet M. Lugt,&nbsp;Frieder Mugele","doi":"10.1007/s11249-026-02138-9","DOIUrl":"10.1007/s11249-026-02138-9","url":null,"abstract":"<div><p>Grease lubrication is among the oldest and most widely employed strategies for reducing friction in tribological contacts. Nevertheless, important microscopic mechanisms that govern the release and transport of lubricants in, say, rolling bearings remain poorly understood. Here, we show how the release of lubricating oil from grease reservoirs and its subsequent spreading toward the rolling contact can be controlled by different treatments of the underlying surface. We demonstrate that smooth, flat oxide surfaces, where oil films are stabilized exclusively by molecular wetting forces, are unable to extract and spread appreciable amounts of oil. In contrast, functionalizing the surface by topographic roughening and/or by coatings of swelling oleophilic polymer brushes can enhance the oil extraction by over two orders of magnitude. Specifically, polymer brushes with an intrinsic phase transition are shown to enable an adaptive lubrication scheme, where the amount of lubricant provided increases rapidly when the temperature rises beyond the melting temperature of the surface-grafted polymer coating.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"74 2","pages":""},"PeriodicalIF":3.3,"publicationDate":"2026-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-026-02138-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147643111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}