Origin Of The Tribofilm From Mos,
2021
State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an 710072, China
Origin Of The Tribofilm From Mos, Hongxing Wu, Liping Wang, Guangneng Dong
Friction
The lubrication effectiveness of MoS2 nanoparticles as an oil additive remains unclear, restricting its application in industry to reduce friction. The goal of this work was to explore the lubrication mechanism of MoS2 nanoparticles as an oil additive. In this study, the oil film thickness behaviors of MoS2 nanoparticles in poly-alpha olefin (PAO4) base oil, PAO4 with 3 wt% dispersant (polyisobutyleneamine succinimide, PIBS), and 0W20 engine oil were investigated using an elastohydrodynamic lubrication (EHL) testing machine. Following the EHL tests, the flow patterns around the contact area and the tribofilm covering rate on contact area were studied …
Is Laser Surface Texturing Good Or Bad For Rolling Element Bearings?,
2021
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Is Laser Surface Texturing Good Or Bad For Rolling Element Bearings?, Yonggang Meng
Friction
A short commentary on the two researcharticles published in Friction in 2021 is presented. Both articles reported experimental results of applications of laser surface texturing technology to the raceway of rolling element bearings. After briefly reviewing the main findings of the articles, the arguable problems and distinctions between the two articles are pointed out.
A Low-To-High Friction Transition In Gradient Nano-Grained Cu And Cu-Ag Alloys,
2021
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;Nano and Heterogeneous Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
A Low-To-High Friction Transition In Gradient Nano-Grained Cu And Cu-Ag Alloys, Xiang Chen, Zhong Han
Friction
A unique low-to-high friction transition is observed during unlubricated sliding in metals with a gradient nano-grained (GNG) surface layer. After persisting in the low-friction state (0.2-0.4) for tens of thousands of cycles, the coefficients of friction in the GNG copper (Cu) and copper-silver (Cu-5Ag) alloy start to increase, eventually reaching a high level (0.6-0.8). By monitoring the worn surface morphology evolution, wear-induced damage accumulation, and worn subsurface structure evolution during sliding, we found that the low-to-high friction transition is strongly correlated with distinct microstructural instabilities induced by vertical plastic deformation and wear-off of the stable nanograins in the subsurface layer. …
Exploring The Role Of --Nh,
2021
Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China
Exploring The Role Of --Nh, Hanqiang Wu, Liang Jiang, Xia Zhong, Jinwei Liu, Na Qin, Linmao Qian
Friction
Ethylenediamine with two -NH2 functional groups was used as a critical complexing agent in chemical mechanical polishing (CMP) slurries for a high carbon chromium GCr15 bearing steel (equivalent to AISI 52100). The polishing performance and corresponding mechanism of -NH2 functional groups were thoroughly investigated as a function of pH. It is revealed that, when polished with ethylenediamine and H2O2-based slurries, the material removal rate (MRR) and surface roughness Ra of GCr15 steel gradually decrease as pH increases. Compared with acidic pH of 4.0, at alkaline pH of 10.0, the surface film of GCr15 …
Enhanced Micro/Nano-Tribological Performance In Partially Crystallized 60niti Film,
2021
Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Xi’an Jiaotong University, Xi’an 710049, China
Enhanced Micro/Nano-Tribological Performance In Partially Crystallized 60niti Film, Wanjun He, Qunfeng Zeng
Friction
The microstructure, mechanical and micro/nano-tribological properties of the 60NiTi film annealed at different temperature were investigated. The results reveal that annealing as-deposited 60NiTi film at 300, 375, and 600 °C for 1 h leads to structural relaxation, partial crystallization and full crystallization, respectively. Compared with the structurally relaxed structure, the partially crystallized structure exhibits increased hardness but decreased elastic modulus. This is because that the elastic modulus is reduced by Voigt model while the hardness is improved by composite effect. Due to the highest hardness and ratio of hardness to elastic modulus (H/E), the partially crystallized 60NiTi film has the …
Graphite-Based Solid Lubricant For High-Temperature Lubrication,
2021
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Graphite-Based Solid Lubricant For High-Temperature Lubrication, Wenjuan Huai, Chenhui Zhang, Shizhu Wen
Friction
High-temperature solid lubricants play a significant role in the hot metal forming process. However, preparing high-temperature solid lubricant is formidably challenging due to the stern working conditions. Here we successfully develop a new type of eco-friendly high-temperature graphite-based solid lubricant by using amorphous silica dioxide, aluminum dihydrogen phosphate, and solid lubricant graphite. The solid lubricating coating exhibits excellent tribological properties with a very low friction coefficient and good wear protection for workpiece at high temperature under the air atmosphere. An array of analytical techniques reveals the existence of solid lubricant graphite in the lubricating coating after the high-temperature friction test. …
Adhesion And Friction In Hard And Soft Contacts: Theory And Experiment,
2021
Technische Universität Berlin, Berlin 10623, Germany;National Research Tomsk State University, Tomsk 634050, Russia
Adhesion And Friction In Hard And Soft Contacts: Theory And Experiment, Valentin L. Popov, Qiang Li, Iakov A. Lyashenko, Roman Pohrt
Friction
This paper is devoted to an analytical, numerical, and experimental analysis of adhesive contacts subjected to tangential motion. In particular, it addresses the phenomenon of instable, jerky movement of the boundary of the adhesive contact zone and its dependence on the surface roughness. We argue that the "adhesion instabilities" with instable movements of the contact boundary cause energy dissipation similarly to the elastic instabilities mechanism. This leads to different effective works of adhesion when the contact area expands and contracts. This effect is interpreted in terms of "friction" to the movement of the contact boundary. We consider two main contributions …
Asperity-Based Modification On Theory Of Contact Mechanics And Rubber Friction For Self-Affine Fractal Surfaces,
2021
Texas State University, 601 University Drive, San Marcos, Texas 78666, USA
Asperity-Based Modification On Theory Of Contact Mechanics And Rubber Friction For Self-Affine Fractal Surfaces, Anahita Emami, Seyedmeysam Khaleghian, Saied Taheri
Friction
Modeling the real contact area plays a key role in every tribological process, such as friction, adhesion, and wear. Contact between two solids does not necessarily occur everywhere within the apparent contact area. Considering the multiscale nature of roughness, Persson proposed a theory of contact mechanics for a soft and smooth solid in contact with a rigid rough surface. In this theory, he assumed that the vertical displacement on the soft surface could be approximated by the height profile of the substrate surface. Although this assumption gives an accurate pressure distribution at the interface for complete contact, when no gap …
Does Laser Surface Texturing Really Have A Negative Impact On The Fatigue Lifetime Of Mechanical Components?,
2021
Institute for Engineering Design and Product Development, TU Wien, Lehárgasse 6, Campus Getreidemarkt, Vienna 1060, Austria;Chair of Functional Materials, Saarland University, Campus D3.3, Saarbrücken 66123, Germany;AC2T Research GmbH, Viktor-Kaplan-Straße 2/C, Wiener Neustadt 2700, Austria
Does Laser Surface Texturing Really Have A Negative Impact On The Fatigue Lifetime Of Mechanical Components?, Chia-Jui Hsu, Andreas Stratmann, Simon Medina, Georg Jacobs, Frank Mücklich, Carsten Gachot
Friction
Laser surface texturing (LST) has been proven to improve the tribological performance of machine elements. The micro-scale patterns manufactured by LST may act as lubricant reservoirs, thus supplying oil when encountering insufficient lubrication. However, not many studies have investigated the use of LST in the boundary lubrication regime, likely due to concerns of higher contact stresses that can occur with the increasing surface roughness. This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication. A series of periodic patterns were produced on the thrust rolling bearings, using two geometrically different …
Artificial Intelligence-Based Predictive Model Of Nanoscale Friction Using Experimental Data,
2021
University of Rijeka, Faculty of Engineering, 51000Rijeka, Croatia;University of Rijeka, Centre for Micro- and Nanosciences and Technologies & Center for Artificial Intelligence and Cybersecurity, 51000Rijeka, Croatia
Artificial Intelligence-Based Predictive Model Of Nanoscale Friction Using Experimental Data, Marko Perčić, Saša Zelenika, Igor Mezić
Friction
A recent systematic experimental characterisation of technological thin films, based on elaborated design of experiments as well as probe calibration and correction procedures, allowed for the first time the determination of nanoscale friction under the concurrent influence of several process parameters, comprising normal forces, sliding velocities, and temperature, thus providing an indication of the intricate correlations induced by their interactions and mutual effects. This created the preconditions to undertake in this work an effort to model friction in the nanometric domain with the goal of overcoming the limitations of currently available models in ascertaining the effects of the physicochemical processes …
Black Phosphorus Quantum Dots: A New-Type Of Water-Based High-Efficiency Lubricant Additive,
2021
School of Biological and Chemical Engineering, Panzhihua University, Panzhihua 617000, China
Black Phosphorus Quantum Dots: A New-Type Of Water-Based High-Efficiency Lubricant Additive, Weiwei Tang, Zhiqiang Jiang, Baogang Wang, Yufeng Li
Friction
Black phosphorus quantum dots (BPQDs), obtained via a typical solution-based top-down method, were used as water-based lubricant additives. BPQDs exhibited remarkable friction reduction and anti-wear properties even at the ultra-low concentration of 0.005 wt%, which reduced the friction coefficient and wear volume of the base liquid by 32.3% and 56.4%, respectively. In addition, the load-supporting capacity of the base liquid increased from 120 N to over 300 N. BPQDs-based additives exhibited a relatively long lifetime at a relatively high load of 80 N. The performance of BPQDs considerably exceeded that of the BP; this may be attributed to their small …
Stability Analysis Of Long Hydrodynamic Journal Bearings Based On The Journal Center Trajectory,
2021
State Key Lab of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Stability Analysis Of Long Hydrodynamic Journal Bearings Based On The Journal Center Trajectory, Yu Huang, Haiyin Cao, Zhuxin Tian
Friction
In this study, we observe that there are two threshold speeds (stability threshold speed and second threshold speed) for the long journal bearing, which is different for the short bearing. When the rotating speed is below the stability threshold speed, the stability boundary nearly coincides with the clearance circle, and the journal center gradually returns to the equilibrium point after being released at an initial point. If the rotating speed is between the stability threshold speed and the second threshold speed, after being released at an initial point, the journal center converges to a contour containing the equilibrium point. In …
Interdependence Of Friction, Wear, And Noise: A Review,
2021
Cranfield University, MK43 0AL, UK
Interdependence Of Friction, Wear, And Noise: A Review, Kevin Lontin, Muhammad Khan
Friction
Phenomena of friction, wear, and noise in mechanical contacts are particularly important in the field of tribomechanics but equally complex if one wants to represent their exact relationship with mathematical models. Efforts have been made to describe these phenomena with different approaches in past. These efforts have been compiled in different reviews but most of them treated friction, wear mechanics, and acoustic noise separately. However, an in-depth review that provides a critical analysis on their interdependencies is still missing. In this review paper, the interdependencies of friction, wear, and noise are analysed in the mechanical contacts at asperitical level. The …
New Strategy For Reducing The Ehl Friction In Steel Contacts Using Additive-Formed Oleophobic Boundary Films,
2021
Laboratory for Tribology and Interface Nanotechnology, Faculty of Mechanical Engineering, University of Ljubljana, Bogišićeva 8, 1000Ljubljana, Slovenia
New Strategy For Reducing The Ehl Friction In Steel Contacts Using Additive-Formed Oleophobic Boundary Films, Mitjan Kalin, Maja Kus
Friction
In this study we present a mechanism for the elastohydrodynamic (EHD) friction reduction in steel/steel contacts, which occurs due to the formation of oleophobic surface boundary layers from common boundary-lubrication additives. Several simple organic additives (amine, alcohol, amide, and fatty acid) with different molecular structures were employed as the model additives. It was found that the stronger chemisorption at 100 ℃, rather than the physisorption at 25 ℃, is more effective in friction reduction, which reaches 22%. What is more, EHD friction reduction was obtained in steel/steel contacts without use of the diamond-like carbon (DLC) coatings with their wetting or …
Improvement Of The Lubrication Properties Of Grease With Mn,
2021
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
Improvement Of The Lubrication Properties Of Grease With Mn, Bao Jin, Guangyan Chen, Jun Zhao, Yongyong He, Yiyao Huang, Jianbin Luo
Friction
Although grease can effectively lubricate machines, lubrication failure may occur under high speed and heavy load conditions. In this study, Mn3O4/graphene nanocomposites (Mn3O4#G) were synthetized using a hydrothermal method as lubricant additives. The lubrication properties of compound grease with Mn3O4#G nanocomposite additive under heavy contact loads of 600-900 N (3.95-4.59 GPa) were investigated. First, the nanocomposites were dispersed into L-XBCEA 0 lithium grease via successive electromagnetic stirring, ultrasound vibration, and three-roll milling. Compound grease with additives of commercial graphene (Com#G) was also investigated for comparison. Tribological test results …
Effect Of Interaction Between Cementite And Pearlite On Two-Body Abrasive Wear Behaviors In White Cast Iron,
2021
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou 510632, China
Effect Of Interaction Between Cementite And Pearlite On Two-Body Abrasive Wear Behaviors In White Cast Iron, Baochao Zheng, Wei Li, Xiaohui Tu, Jiandong Xing, Suocheng Song
Friction
The wear interaction of cementite and pearlite in the white cast iron (WCI) was investigated using the two-body abrasive wear test under contact loads of 20, 35, and 50 N. The wear behavior, wear surface morphology, sub-surface structure, and wear resistance were evaluated using X-ray diffraction, microhardness testing, and nano-indentation. The results indicated that when the Cr content was increased from 0 to 4 wt%, there was a significant increase in the microhardness (H) and elasticity modulus (E) of the cementite. This yielded a 15.91%- and 23.6%-reduction in the degree of wear resistance and surface roughness, respectively. Moreover, no spalling …
Penetration And Lubrication Evaluation Of Vegetable Oil With Nanographite Particles For Broaching Process,
2021
School of Mechanical Engineering, Hangzhou Dianzi University, Hangzhou 310018, China
Penetration And Lubrication Evaluation Of Vegetable Oil With Nanographite Particles For Broaching Process, Ming Xu, Xin Yu, Jing Ni
Friction
With increasing environmental concerns, the substitution of mineral oil-based cutting fluid has become an urgent issue. Using vegetable soybean oil as base fluid, nanofluid cutting fluids (NFCFs) were prepared by adding different weight concentrations of nanographite particles (NGPs), and their penetration and lubrication performances were studied. A novel simulated tool-chip slit with micrometer-sized geometry was manufactured to evaluate and quantify the penetration rate of the NFCFs by image analysis approach. Moreover, a large number of comparative experiments on the closed-type broaching machine were carried out to compare the performance of the proposed NFCFs and a commercial cutting fluid in terms …
Effect Of Temperature And Mating Pair On Tribological Properties Of Dlc And Glc Coatings Under High Pressure Lubricated By Modtc And Zddp,
2021
School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China
Effect Of Temperature And Mating Pair On Tribological Properties Of Dlc And Glc Coatings Under High Pressure Lubricated By Modtc And Zddp, Kang Liu, Jia-Jie Kang, Guang-An Zhang, Zhi-Bin Lu, Wen Yue
Friction
Diamond-like carbon (DLC) and graphite-like carbon (GLC) coatings have good prospects for improving the surface properties of engine parts. However, further understanding is needed on the effect of working conditions on tribological behaviors. In this study, GLC and two types of DLC coatings were deposited on GCr15 substrate for investigation. The friction and wear properties of self-mated and steel-mated pairs were evaluated. Two temperatures (25 and 90 ℃), three lubrication conditions (base oil, molybdenum dithiocarbamate (MoDTC)-containing oil, MoDTC+zinc dialkyldithiophosphate (ZDDP)-containing oil), and high Hertz contact stress (2.41 GPa) were applied in the experiments. The results showed that high temperature promoted …
A Calculation Method For Friction Coefficient And Meshing Efficiency Of Plastic Line Gear Pair Under Dry Friction Conditions,
2021
School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China
A Calculation Method For Friction Coefficient And Meshing Efficiency Of Plastic Line Gear Pair Under Dry Friction Conditions, Yangzhi Chen, Yifan Lin
Friction
A calculation method for the friction coefficient and meshing efficiency of plastic line gear (LG) pair under dry friction conditions was studied theoretically and experimentally, taking a polyoxymethylene parallel line gear pair (POM PLGP) as an example. Firstly, the geometric and mechanical models of PLGP were built by considering the effects of misalignment and loaded deformation under the actual operating condition. Then, the friction coefficient of POM specimens was obtained via the ball-on-disk experiment, of which the value varies between 0.35 and 0.45 under the experimental conditions. The calculation formula for the friction coefficient of POM LG pair was obtained …
An Efficient Three-Dimensional Foil Structure Model For Bump-Type Gas Foil Bearings Considering Friction,
2021
School of Aerospace Engineering, Tsinghua University, Beijing 100084, China
An Efficient Three-Dimensional Foil Structure Model For Bump-Type Gas Foil Bearings Considering Friction, Yongpeng Gu, Xudong Lan, Gexue Ren, Ming Zhou
Friction
This paper presents an efficient three-dimensional (3D) structural model for bump-type gas foil bearings (GFBs) developed by considering friction. The foil structures are modeled with a 3D shell finite element model. Using the bump foil mechanical characteristics, the Guyan reduction and component mode synthesis methods are adopted to improve computational efficiency while guaranteeing accurate static responses. A contact model that includes friction and separation behaviors is presented to model the interactions of the bump foil with the top foil and bearing sleeve. The proposed structural model was validated with published analytical and experimental results. The coupled elastohydrodynamics model of GFBs …
