Tribology Letters最新文献

{"title":"Role of Oxygen Content and Humidity on Adhesion and Damage Behavior of Wheel-Rail Interface Under Low Temperature","authors":"Yanwen Lin,&nbsp;Yongjiang Wang,&nbsp;Jiaqiang Li,&nbsp;Jingyi Wang,&nbsp;Chunying Ma,&nbsp;Mingxue Shen","doi":"10.1007/s11249-025-01987-0","DOIUrl":"10.1007/s11249-025-01987-0","url":null,"abstract":"<div><p>The adhesion and damage behavior of the wheel-rail contact is crucial for the safety of railway operations. To investigate the effects of oxygen content and humidity of airflow on the adhesion and damage behavior of the wheel-rail interface, tribological testing of the wheel-rail interface is conducted using a rolling-sliding contact in the laboratory. Results show that the adhesion coefficient of the wheel-rail interface decreases with the increase of relative humidity (RH). The content of Fe²⁺ increases with the increase of humidity of the airflow, which promotes hydration reactions. Specifically, under the condition of RH = 50%, the presence of an appropriate amount of water molecules in the environment, results in a higher degree of oxidation on the worn surface of the wheels and the formation of a large amount of oxides. Furthermore, Fe³⁺ and Fe²⁺ are easily generated on the surface when the oxygen content around the environment is sufficient or insufficient, respectively. In the oxygen enrichment condition, a higher amount of Fe₂O₃ is observed, whereas for the hypoxic condition, the oxide film cannot be quickly formed again after being damaged, resulting in more severe wear on the wheel-rail interface because of the lower oxygen content in the surrounding environment. This work provides critical insights into the friction properties as well as wear mechanism in response to humidity and oxygen content when the wheel-rail interface encounters the humid and warm airflow with different humidity levels in the tunnel, which is crucial for proposing effective measures to improve the adhesion of wheel-rail interface and avoid the occurrence of the low adhesion problems.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143698490","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":"Effect of Metal Composition on Mechanical Properties of Tribofilms","authors":"David C. Roache,&nbsp;Mark Devlin,&nbsp;Xiaodong Li","doi":"10.1007/s11249-025-01979-0","DOIUrl":"10.1007/s11249-025-01979-0","url":null,"abstract":"<div><p>Low-speed pre-ignition (LSPI), where hot spots in the combustion chamber can cause fuel ignition to occur, can result in increased pressure in the combustion chamber, causing damage to the system and negatively affecting emissions. These hot spots have been identified as calcium (Ca) deposits, causing a push to reduce Ca in engine oils. For this study, tribofilms were generated with an amount of Ca so that LSPI did not occur. Zinc dialkyldithiophosphate (ZDDP), Ca, and magnesium (Mg) detergents were kept constant, with the metal in the tribofilm adjusted by varying the surfactants (friction modifiers) in the engine oil, ensuring enough ZDDP and detergent to be able to protect the engines. Energy dispersive x-ray spectroscopy (EDS) and atomic force microscopy (AFM) revealed three distinct tribofilm components: smooth, streaky films, deeper worn steel, and a mixed region of rougher tribofilm growth. Tribofilms with higher Ca had lower bulk friction than those with higher Zn, while AFM friction maps of the different sections showed that the friction in the mixed region was similar in magnitude to macro-scale friction, but film and substrate COF were much lower. Similarly, AFM modulus mapping of the mixed region showed higher Ca contributing to increased modulus when compared to Zn. Nanoindentation across the entire tribofilm revealed that higher modulus in the film and mixed regions contributed to more effective tribofilm coverage. Overall, Ca was shown to be critical to the wear and friction performance of tribofilms and their mechanical properties even when reduced to avoid LSPI.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143667960","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":"Modelling Friction Reduction Based on Molybdenum Disulphide Tribofilm Formation and Removal in Boundary Lubrication","authors":"Dichu Xu,&nbsp;Cayetano Espejo,&nbsp;Chun Wang,&nbsp;Ardian Morina","doi":"10.1007/s11249-025-01981-6","DOIUrl":"10.1007/s11249-025-01981-6","url":null,"abstract":"<div><p>Molybdenum dialkyldithiocarbamate is a highly effective friction modifier lubricant additive in boundary lubrication, owing to the formation of a MoS₂ nanosheet lattice structure that significantly reduces friction. The friction reduction behaviour is linked to the MoS₂ amount and coverage buildup at the contacting interface, however, accurately predicting friction reduction based on a semi-deterministic model incorporating MoS₂ formation and removal remains challenging. In this study, a Raman map collection methodology was developed for accurate quantitative analysis of MoS₂ tribofilms. The growth rate of MoS₂ tribofilms was determined by coupling tribochemical experimental data with sophisticated numerical models. A full numerical procedure was implemented under rubbing of two rough surfaces at different temperatures. The results demonstrated localised MoS₂ tribofilms buildup. The friction coefficients show a close agreement with the measurements. The developed model can be adapted to diverse experimental setups and surface geometries.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-025-01981-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632480","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":"The Corrosion Performance and Post-corrosion Wear Mechanisms of Fully Formulated Lubricants Introduced Varying Hydrogen","authors":"Xinbo Wang,&nbsp;Lili Jin,&nbsp;Hao Zhang,&nbsp;Ruifeng Xu,&nbsp;Yansong Liu,&nbsp;Oleksandr Stelmakh,&nbsp;Baigang Sun","doi":"10.1007/s11249-025-01982-5","DOIUrl":"10.1007/s11249-025-01982-5","url":null,"abstract":"<div><p>Hydrogen internal combustion engines are transitional power devices for cleaner and low-carbon energy in transportation. However, high-temperature engine lubricants are prone to contact with hydrogen and oxygen, flowing through metal components during operation. The corrosive properties of the lubricants containing these gases and their tribological performance after prolonged contact with gases and engine metal parts have yet to be studied. This paper investigates the corrosive properties of fully formulated lubricants contacted with steel and metal coupons with air and varying flow rates of hydrogen introduced, as well as the tribological performance of the post-corrosion lubricants. The results show that as the hydrogen flow rate increases from 0 to 12 lph, the weight loss rates of copper and lead coupons decrease by 74.4% and 79.7%. Energy-dispersive spectroscopy and gas chromatography–mass spectrometry confirmed the reduction in oxygen content on the metal surfaces and the degradation of additives such as diphenylamine by hydrogen during corrosion. Compared to those without hydrogen, the friction coefficients of the lubricants after exposure to metal and steel coupons and 12 lph of hydrogen decreased by 50.4% and 46.6%. This significant improvement in lubrication performance is attributed to the reduced degradation of ZDDP and the formation of more zinc phosphate and zinc sulfide during friction in the hydrogen-introduced post-corrosion lubricants, compared to post-corrosion lubricants without hydrogen exposure. The research of corrosive and tribological performance characteristics can be applied to enhance the design of reliable engine tribo-pairs and improve the lubrication requirements of engine oil in hydrogen environments.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632479","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 Electric Potentials on Surface Damage in Rolling–Sliding Contacts Under Mixed Lubrication","authors":"Ammad Yousuf,&nbsp;Hugh Spikes,&nbsp;Liang Guo,&nbsp;Amir Kadiric","doi":"10.1007/s11249-025-01977-2","DOIUrl":"10.1007/s11249-025-01977-2","url":null,"abstract":"<div><p>Shaft voltages in electric vehicle drivetrains are believed to be capable of causing significant damage to rolling bearing surfaces. While surface damage due to high current discharge in full-film lubrication is relatively well understood, the effects of electric potentials on surface damage and tribofilm formation in thin-film, mixed lubrication are rarely studied and remain poorly understood. This paper investigates the influence of relatively low DC potentials (1 V, 5 V) and currents (&lt;10 mA) on wear and tribofilm growth in rolling–sliding contacts in operating mixed lubrication. A suitably modified ball-on-disc MTM-SLIM rig is used to apply an electric potential across a lubricated ball-on-disc contact. Tests were conducted with bearing steel specimens and three oils: PAO base oil, PAO with antiwear additive ZDDP, and a commercial automatic transmission fluid (ATF). The effect of electric polarity was an integral part of the study. The results reveal that even small electric potentials and currents significantly affect wear. For the oil containing ZDDP, electric potential both suppressed the formation of tribofilm and significantly increased the wear on the anodic surface, be it the ball or the disc. The wear was localised in discrete bands within the rubbing track. ZDDP film was shown to be electrically resistive and it is postulated that the non-uniform nature of the ZDDP film leads to the concentration of current within the thin-film regions and this high current density causes wear in these local areas (wear bands) via electric discharge. In contrast, with the ATF, electric potential promoted tribofilm on the anode but resulted in higher wear on the cathode disc. The study highlights a complex interplay between the electric potential, tribofilm formation, the consequent distribution of electrical resistance within the contact, and the resulting wear evolution.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-025-01977-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612264","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":"Resistance to Oxidation and Tribological Behavior of MoS2 Nanoparticles in Severe Environmental Conditions","authors":"Marina Benmansour,&nbsp;Pavel Afanasiev,&nbsp;Jules Galipaud,&nbsp;Lucile Joly-Pottuz,&nbsp;Fabrice Dassenoy","doi":"10.1007/s11249-025-01980-7","DOIUrl":"10.1007/s11249-025-01980-7","url":null,"abstract":"<div><p>This study investigates the oxidation resistance and tribological performance of MoS₂ nanoparticles under severe environmental conditions. Friction tests were conducted in dry and strictly controlled environments using a reciprocating pin-on-flat tribometer installed in a controlled environment chamber. This system was connected via a transfer chamber to an XPS spectrometer, enabling post-mortem analysis of the rubbed surfaces without air exposure. The friction tests were performed under pressures ranging from 10⁻⁹ to 200 mbar (simulating ambient air) and at two temperatures (25 and 100 °C). The results show that the nanoparticles maintain excellent tribological performance and good chemical stability from ultrahigh vacuum up to 200 mbar of oxygen at 25 °C, and up to 1 mbar of oxygen at 100 °C. The increase in the friction coefficient observed under certain experimental conditions is attributed to particle oxidation.</p></div>","PeriodicalId":806,"journal":{"name":"Tribology Letters","volume":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-025-01980-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602319","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":"High Temperature Induced Brittle-Ductile Transition of Monocrystalline Silicon via In Situ Indentation","authors":"Zerui Zhao,&nbsp;Xianke Li,&nbsp;Xinhang Yang,&nbsp;Hao Wu,&nbsp;Chi Zhang,&nbsp;Shunbo Wang,&nbsp;Hongwei Zhao","doi":"10.1007/s11249-025-01974-5","DOIUrl":"10.1007/s11249-025-01974-5","url":null,"abstract":"<div><p>Monocrystalline silicon is difficult to molding process due to the unknown mechanism of temperature-influenced brittle-plastic transition. Indentation test of monocrystalline silicon from room temperature (RT) to 500 °C was carried out within scanning electron microscope (SEM). Evolution of surface damage mode at elevated temperatures was in situ observed. Cracking and extrusion occurred during indentation of monocrystalline silicon from RT to 200 °C, while shallow scallop-shell lateral peeling was found to be generated by a combination of secondary radial crack and shallow lateral crack. The phenomenon of surface peeling disappeared at 300 °C. The plasticity of the material significantly increased. Dislocation motion coexists but competes with microcrack nucleation-expansion with temperature increasing. The completion of the brittle-plastic transition is evident at 500 °C. Cracks are no longer generated on the surface and pile-up phenomenon is enhanced. This discovery demonstrates the feasibility of plastic molding processing of monocrystalline silicon at high temperatures.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602421","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":"Effects of Asperity Shapes and Normal Loads on Adhesive Wear Mechanisms","authors":"Xiaohu Wu,&nbsp;Fuli Zhang,&nbsp;Huanxiong Xia,&nbsp;Lin Zhang,&nbsp;Jianhua Liu,&nbsp;Xuerui Zhang,&nbsp;Xiaohui Ao,&nbsp;Juncheng Luo","doi":"10.1007/s11249-025-01978-1","DOIUrl":"10.1007/s11249-025-01978-1","url":null,"abstract":"<div><p>How the shape of asperities affects the wear behavior is still an open question in contact mechanics. This work developed adhesive wear models including the deformable spherical and sinusoidal asperities in contact with a rigid flat by introducing the ductile failure criterion. For spherical asperity, fractures propagating at the corner and then forming spherical-like wear particles are observed under high normal loads, indicating a new Archard-like wear mode. For sinusoidal asperity, it is almost flattened under high normal loads, yielding lamellar wear particles; the wear rate rises first and then decreases as the normal load increases, and both the peak wear rate and the corresponding normal load greatly depend on its shape.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533226","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":"Activation Volumes in Tribochemistry; What Do They Mean and How to Calculate Them?","authors":"Nicholas Hopper,&nbsp;Resham Rana,&nbsp;François Sidoroff,&nbsp;Juliette Cayer-Barrioz,&nbsp;Denis Mazuyer,&nbsp;Wilfred T. Tysoe","doi":"10.1007/s11249-025-01975-4","DOIUrl":"10.1007/s11249-025-01975-4","url":null,"abstract":"<div><p>Analyzing the effect of pressures and normal and shear stresses on chemical reaction rates, especially those occurring in a contact, remains the subject of controversy in the scientific community. This review article aims to clarify the principles that underpin the calculation of reaction rates based on transition-state theory (TST) and of activation volumes using a perturbation method of TST proposed by Evans and Polanyi. The goal is to aid researchers to calculate such tribochemical and mechanochemical parameters. In this paper, the fundamental ideas behind the calculation of reaction rates in chemistry are outlined. This article describes how TST is used to account for the large numbers of molecules involved in chemical reactions. The effects of individual stresses, and combination of normal and shear stresses on tribochemical reaction rates can be understood using a thermodynamics analysis. These concepts are illustrated by two examples of normal-stress-modified processes from results in the literature: homogeneous-phase Diels–Alder reactions and the surface decomposition of adsorbed methyl thiolate species on copper. The paper then reviews how to analyze tribochemical processes, which depend on coupled normal and shear stresses, showing that the effective activation volume is composed of multiple elementary-process activation volumes. Compensation effects, in which the pre-exponential factors and the activation volumes are correlated have been found for tribochemical reactions and this arises naturally from the Evans–Polanyi analysis. Finally, the activation volumes themselves depend on the applied stresses due to molecular distortions and a method for gauging the magnitude of these effects is described.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481180","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":"Elastohydrodynamic Lubrication Mechanisms of Aqueous Polyethylene Glycols","authors":"Stefan Hofmann,&nbsp;Jingyu Hou,&nbsp;Thomas Lohner,&nbsp;Karsten Stahl","doi":"10.1007/s11249-025-01962-9","DOIUrl":"10.1007/s11249-025-01962-9","url":null,"abstract":"<div><p>Water-soluble polyalkylene glycols have become a growing subject of research to achieve liquid superlubricity in elastohydrodynamically lubricated contacts. While the influence of various factors, including water content and viscosity, has been extensively studied, the underlying mechanisms responsible for liquid superlubricity under elastohydrodynamic lubrication remain poorly understood. In this study, aqueous polyethylene glycols of varying average chain length with the same viscosity but different water content or average chain length distribution are examined in relation to elastohydrodynamic friction and film thickness. The results indicate, that under fluid film lubrication, the low pressure–viscosity coefficient is the primary factor leading to liquid superlubricity. No running-in period is required, allowing for stable and persistent ultra-low friction level immediately. Additionally, at a constant water content, an optimum average chain length distribution was identified, resulting in reduced friction while the film thickness remained largely unaffected. This enables the targeted design of aqueous lubricants based on polyethylene glycol.</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":"73 2","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11249-025-01962-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481179","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}