FrictionPub Date : 2024-08-14DOI: 10.1007/s40544-024-0916-1
Stefan Hofmann, Thomas Lohner, Karsten Stahl
{"title":"Influence of water evaporation on elastohydrodynamic lubrication with water-containing polyalkylene glycols","authors":"Stefan Hofmann, Thomas Lohner, Karsten Stahl","doi":"10.1007/s40544-024-0916-1","DOIUrl":"https://doi.org/10.1007/s40544-024-0916-1","url":null,"abstract":"<p>The reduction of frictional power losses in power transmitting gears takes a crucial role in the design of energy- and resource-efficient drivetrains. Water-containing lubricants like glycerol and polyalkylene glycols have shown great potential in achieving friction within the superlubricity regime with coefficients of friction lower than 0.01 under elastohydrodynamic lubrication. Additionally, a bio-based production of the base stocks can lead to the development of green lubricants. However, one challenge associated with the application of water-containing lubricants to gearboxes is the evaporation of water and its impact on the lubricant properties. In this study, the influence of water evaporation on elastohydrodynamic friction and film thickness was investigated for three water-containing polyalkylene glycols. Two nominal water contents of 20 wt% and 40 wt% and two viscosities were considered. The results show that the friction increases continuously with higher evaporated water content, while the overall friction level remains low in nearly water-free states. A similar trend is observed for film thickness, where the strong increase in viscosity results in a notable increase in film thickness. Nevertheless, the sensitivity of friction and film thickness to water evaporation is low for small amounts of evaporated water. This allows generous thresholds for permissible variations in water content.\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"36 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-08-14DOI: 10.1007/s40544-024-0888-1
Zhuocheng Li, Enhui Zhang, Weimin Li, Haichao Liu
{"title":"Tribological study of two ammonium chloride-decanoic acid deep eutectic solvents (DESs) as high-performance lubricants","authors":"Zhuocheng Li, Enhui Zhang, Weimin Li, Haichao Liu","doi":"10.1007/s40544-024-0888-1","DOIUrl":"https://doi.org/10.1007/s40544-024-0888-1","url":null,"abstract":"<p>Deep eutectic solvents (DESs) are acknowledged as a novel class of functional liquid. DESs share similar physical properties with ionic liquids (ILs) and have the potential to be a novel class of lubricants. In this study, two DESs, namely tetrabutylammonium chloride-decanoic acid DES (C4-DES) and methyl tricaprylmethylammonium chloride-decanoic acid DES (C8-DES), were synthesized, and their physico-chemical properties and tribological performances were evaluated. Post-analysis of the rubbing surfaces used multiple techniques to gain insights into the lubrication mechanisms. Results show that the coefficient of friction (COF) and wear were reduced by approximately 29% and 91% for the C4-DES, and 36% and 94% for the C8-DES, compared to an ester base oil. The friction reduction behavior of the DESs is attributed to the monolayer adsorption of the polar group in the decanoic acid (DEAC), whose effectiveness is affected by the component of the ammonium salts in the DESs and the operating temperatures. In addition to the adsorbed film, worn surface analysis revealed that an ultra-thin tribochemical film with a thickness of 3–7 nm was formed on the surfaces lubricated with the C8-DES. The composition of the film was studied, and the lubrication mechanisms of the two DESs were discussed.</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"14 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-08-06DOI: 10.1007/s40544-024-0896-1
Runliang Wang, Jianhua Liu, Bo Liu, Duo Jia, Xiaoyu Ding
{"title":"Experimental investigation of junction growth of rough contacts using X-ray computed tomography","authors":"Runliang Wang, Jianhua Liu, Bo Liu, Duo Jia, Xiaoyu Ding","doi":"10.1007/s40544-024-0896-1","DOIUrl":"https://doi.org/10.1007/s40544-024-0896-1","url":null,"abstract":"<p>The real contact area (RCA) of randomly rough contacts has received a great deal of attention because it correlates strongly with friction, lubrication, sealing, and conductivity. Simulations have revealed that the RCA associated with deterministic normal squeezing loads increases when tangential loads are also applied, in a phenomenon called junction growth. However, experimental investigations of the junction growth of randomly rough contacts are rare. Here, we used X-ray computed tomography (CT) to measure junction growth when two aluminum alloy surfaces were in contact. A high-resolution experimental setup was used to apply loads and observe contact behaviors at a resolution of 4 µm. The RCA and average contact gaps were computed using a three-dimensional (3D) geometric model constructed from gray CT images using the Otsu thresholding method. The results showed that the RCA increased as the normal load increased. The RCA increased by 22.67% after a tangential load was applied (junction growth), and the average gap decreased by 14.01% after a tangential load was applied. Thus, X-ray CT accurately measured the junction growth as a novel quantitative method.</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"11 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141895469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-08-05DOI: 10.1007/s40544-024-0910-7
Lv Wang, Qian Tang, Tao Liang, Chenxu Liu, Deen Sun, Shu Wang, Jingchuan Li, Sam Zhang, Yonggang Meng, Yuehua Huang
{"title":"Lubrication performance of graphene in the sliding electrical contact interface","authors":"Lv Wang, Qian Tang, Tao Liang, Chenxu Liu, Deen Sun, Shu Wang, Jingchuan Li, Sam Zhang, Yonggang Meng, Yuehua Huang","doi":"10.1007/s40544-024-0910-7","DOIUrl":"https://doi.org/10.1007/s40544-024-0910-7","url":null,"abstract":"<p>Electrical contact materials are increasingly widely used, but the existing electric contact lubricants still have lots of room for improvement, such as anti-wear performance and lubrication life. Due to the excellent electrical and lubrication properties, graphene shows great potential in lubricating the sliding electrical contact interface, but there is a lack of relevant research. Some researchers have studied the lubrication performance of graphene between the gold-coated/TiN-coated friction pair at an ultra-low current. However, the lubrication performance of graphene on more widely used electrical contact materials such as copper and its alloys under larger and more commonly used current or voltage conditions has not been reported. In this paper, we study the lubrication performance of graphene in the copper and its alloys sliding electrical contact interface under usual parameters, which is explored through four aspects: different substrates—copper and brass, different test methods—constant voltage and constant current, different normal loads and durability test. The experiments demonstrate that graphene can significantly reduce the friction and wear on brass and copper under the above test methods and parameters, with low contact resistance at the same time. Our work is expected to provide a new lubricant for electrical contact materials and contribute to enriching the tribological theory of graphene.\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"55 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-08-05DOI: 10.1007/s40544-024-0909-0
Jian Pu, Zupei Zhang, Yali Zhang, Xiaogang Zhang, Xinlu Yuan, Xiaoyu Zhang, Guoxian Zhang, Wen Cui, Shu Yang, Zhongmin Jin
{"title":"Fretting-corrosion mechanisms of Ti6Al4V against CoCrMo in simulated body fluid under various fretting states","authors":"Jian Pu, Zupei Zhang, Yali Zhang, Xiaogang Zhang, Xinlu Yuan, Xiaoyu Zhang, Guoxian Zhang, Wen Cui, Shu Yang, Zhongmin Jin","doi":"10.1007/s40544-024-0909-0","DOIUrl":"https://doi.org/10.1007/s40544-024-0909-0","url":null,"abstract":"<p>Ti6Al4V alloy–CoCrMo alloy pair is commonly applied for modular head–neck interfaces for artificial hip joint. Unfortunately, the fretting corrosion damage at this interface seriously restricts its lifespan. This work studied the fretting corrosion of Ti6Al4V–CoCrMo pair in calf serum solution. We established this material pair’s running condition fretting map (RCFM) regarding load and displacement, and revealed the damage mechanism of this material pair in various fretting regimes, namely partial slip regime (PSR), mixed fretting regime (MFR), and gross slip regime (GSR). The damage mechanism of Ti6Al4V alloy was mainly abrasive wear induced by CoCrMo alloy and tribocorrosion. Adhesive wear (material transfer) also existed in MFR. The damage mechanism of CoCrMo alloy was mainly abrasive wear induced by metal oxides and tribocorrosion in GSR and MFR, while no apparent damage in PSR. Furthermore, a dense composite material layer with high hardness was formed in the middle contacting area in GSR, which reduced the corrosion and wear of Ti alloys and exacerbated damage to Co alloys. Finally, the ion concentration maps for Ti and Co ions were constructed, which displayed the transition in the amount of released Ti and Co ions under different displacements and loads.\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"27 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-08-05DOI: 10.1007/s40544-024-0911-6
Jiawei Ji, Wei Sun, Yu Du, Yongqing Zhu, Yuhang Guo, Xiaojun Liu, Yunlong Jiao, Kun Liu
{"title":"Topographic variation and fluid flow characteristics in rough contact interface","authors":"Jiawei Ji, Wei Sun, Yu Du, Yongqing Zhu, Yuhang Guo, Xiaojun Liu, Yunlong Jiao, Kun Liu","doi":"10.1007/s40544-024-0911-6","DOIUrl":"https://doi.org/10.1007/s40544-024-0911-6","url":null,"abstract":"<p>Understanding flow characteristics of fluid near rough contact is important for the design of fluid-based lubrication and basic of tribology physics. In this study, the spreading and seepage processes of anhydrous ethanol in the interface between glass and rough PDMS are observed by a homemade optical <i>in-situ</i> tester. Digital image processing technology and numerical simulation software are adapted to identify and extract the topological properties of interface and thin fluid flow characteristics. Particular attention is paid to the dynamic evolution of the contact interface morphology under different stresses, the distribution of microchannels in the interface, the spreading characteristics of the fluid in contact interface, as well as the mechanical driving mechanism. Original surface morphology and the contact stress have a significant impact on the interface topography and the distribution of interfacial microchannels, which shows that the feature lengths of the microchannels, the spreading area and the spreading rate of the fluid are inversely proportional to the load. And the flow path of the fluid in the interface is mainly divided into three stages: along the wall of the island, generating liquid bridges, and moving from the tip side to the root side in the wedge-shaped channel. The main mechanical mechanism of liquid flow in the interface is the equilibrium between the capillary force that drives the liquid spreading and viscous resistance of solid wall to liquid. In addition, the phenomenon of “trapped air” occurs during the flow process due to the irregular characteristics of the microchannel. This study lays a certain theoretical foundation for the research of microscopic flow behavior of the liquid in the rough contact interface, the friction and lubrication of the mechanical system, and the sealing mechanism.\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"19 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-07-29DOI: 10.1007/s40544-024-0887-2
André Bergmann, Jens Sumpf, Niels Dallinger, Martin Moneke, Markus Golder
{"title":"Semi-analytical calculation model for friction of polymers on the example of POM ∣ PE-UHMW and steel ∣ PE-UHMW","authors":"André Bergmann, Jens Sumpf, Niels Dallinger, Martin Moneke, Markus Golder","doi":"10.1007/s40544-024-0887-2","DOIUrl":"https://doi.org/10.1007/s40544-024-0887-2","url":null,"abstract":"<p>In this paper, a semi-analytical calculation model for the coefficient of friction (COF) of single spherical protrusions is presented. It allows the prediction of the deformative friction part (<i>μ</i><sub>def</sub>) and adhesive friction part (<i>μ</i><sub>adh</sub>) of the friction pairings steel ∣ polyethylene with ultra-high molecular weight (PE-UHMW) and polyoxymethylene (POM) ∣ PE-UHMW. The experimental studies included unlubricated friction tests, which served to determine the total COF (<i>μ</i><sub>tot</sub>), as well as tests being lubricated with silicone oil, from which <i>μ</i><sub>def</sub> is obtained. Based on the verification tests, it could be shown that both states of lubrication result in the same deformation and that the relationship between the rear angle (<i>ω</i>) and <i>μ</i><sub>def</sub> postulated in the calculation model is valid. Therefore, friction tests with segmented spheres were carried out, which allow a specific variation of the <i>ω</i>.</p><p>It can be concluded that for both pairings the <i>μ</i><sub>def</sub> is generally of minor significance (approx. 1/3 <i>μ</i><sub>tot</sub>) and the influence of the <i>μ</i><sub>adh</sub> predominates (approx. 2/3 <i>μ</i><sub>tot</sub>) the friction process. Furthermore the <i>μ</i><sub>tot</sub> decreases with increasing contact pressure especially in the low pressure range and depends on the form of motion (continuous and discontinuous).\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"72 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141791054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-07-24DOI: 10.1007/s40544-024-0933-0
Konstantin Nadein, Alexander Kovalev, Stanislav N. Gorb
{"title":"Tribological properties of the beetle leg joints","authors":"Konstantin Nadein, Alexander Kovalev, Stanislav N. Gorb","doi":"10.1007/s40544-024-0933-0","DOIUrl":"https://doi.org/10.1007/s40544-024-0933-0","url":null,"abstract":"<p>Tribological properties of femoro-tibial leg joints in two beetles, darkling beetle <i>Zophobas morio</i> and Congo rose chafer <i>Pachnoda marginata</i> were studied. Very low friction of 0.004 was revealed by the direct measurements in the joint. It is assumed that semi-solid lubricant functioning as in technical bearings is one of the leading factors of the friction minimization. Dependence of the surface texture and physical chemical properties (hydrophobicity) on the cuticle friction was analysed. Contribution of the surface texture to the tribological properties of contacting surfaces was examined by the measurement in the tribosystem “contacting surface/glass”. It is supposed that coefficient of friction (COF) decreases with decrease of surface roughness. At the same time, no statistically significant correlation was found between the hydrophobicity of the surface and the value of the friction coefficient.\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"16 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141755184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FrictionPub Date : 2024-07-24DOI: 10.1007/s40544-024-0871-x
Tao Yang, Xiaozhen Wang, Huanchen Liu, Qin Zhao, Kuiliang Gong, Weimin Li, Yongmin Liang, Xiaobo Wang
{"title":"An inorganic-organic hybrid CQDs@PVP lubricant additive: Achieving low friction and wear in PEG and water","authors":"Tao Yang, Xiaozhen Wang, Huanchen Liu, Qin Zhao, Kuiliang Gong, Weimin Li, Yongmin Liang, Xiaobo Wang","doi":"10.1007/s40544-024-0871-x","DOIUrl":"https://doi.org/10.1007/s40544-024-0871-x","url":null,"abstract":"<p>High-temperature lubrication has always been a hot topic in the lubricant and grease industry, and is also an essential concern in the high-end equipment sector to be addressed. Carbon quantum dots (CQDs) are an emerging material widely applied in the field of lubrication, owing to their exceptional lubricity and high load-bearing capacity. However, the vulnerability of CQDs to oxidation in air and reduced stability dramatically restrict their high-temperature application capability. In this study, a nanocomposite of amphiphilic polyvinyl pyrrolidone (PVP) homopolymer with excellent lubricating properties and thermal stability, which is hydrogen bonded to CQDs (CQDs@PVP), was designed to achieve low friction and wear of lubricants at high temperatures. The CQDs@PVP are consistently dispersed in both PEG400 and water, and exhibit superior lubricity compared to unmodified CQDs at high temperatures (ranging from 200–150 °C and 90.50 °C). Meanwhile, the dense carbon film on the wear surface and the chemically reactive film of iron compounds directly contribute to the enhanced lubrication performance. These analytical results demonstrate the powerful candidacy of CQDs@PVP as a lubrication additive and promote future high-temperature applications of CQDs in industrial production.</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"3 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Recent developments in functional organic polymer coatings for biomedical applications in implanted devices","authors":"Yinuo Yang, Yiran Jia, Yanran Zhao, Haimang Wang, Hongyu Zhang","doi":"10.1007/s40544-023-0850-7","DOIUrl":"https://doi.org/10.1007/s40544-023-0850-7","url":null,"abstract":"<p>Organic polymer coatings have been commonly used in biomedical field, which play an important role in achieving biological antifouling, drug delivery, and bacteriostasis. With the continuous development of polymer science, organic polymer coatings can be designed with complex and advanced functions, which is conducive to the construction of biomedical materials with different performances. According to different physical and chemical properties of materials, biomedical organic polymer coating materials are classified into zwitterionic polymers, non-ionic polymers, and biomacromolecules. The strategies of combining coatings with substrates include physical adsorption, chemical grafting, and self-adhesion. Though the coating materials and construction methods are different, many biomedical polymer coatings have been developed to achieve excellent performances, i.e., enhanced lubrication, anti-inflammation, antifouling, antibacterial, drug release, anti-encrustation, anti-thrombosis, etc. Consequently, a large number of biomedical polymer coatings have been used in artificial lungs, ureteral stent, vascular flow diverter, and artificial joints. In this review, we summarize different types, properties, construction methods, biological functions, and clinical applications of biomedical organic polymer coatings, and prospect future direction for development of organic polymer coatings in biomedical field. It is anticipated that this review can be useful for the design and synthesis of functional organic polymer coatings with various biomedical purposes.\u0000</p>","PeriodicalId":12442,"journal":{"name":"Friction","volume":"29 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}