scholarly journals Mathematical regularities of the sliding friction process of a porous material based on iron impregnated with lubricating oil with dispersed particles of fluorinated graphene

2021 ◽  
Vol 22 (1) ◽  
pp. 378-389
Author(s):  
Alexander Dzhalyulyevich Breki ◽  
Sergey Georgievich Chulkin ◽  
Nikolay Mikhaylovich Dobrovolsky ◽  
Olga Vladimirovna Kuzovleva ◽  
Alexandr Evgenyevich Gvozdev ◽  
...  
Keyword(s):  
Porous Material ◽  
Sliding Friction ◽  
Lubricating Oil ◽  
Friction Process ◽  
Dispersed Particles ◽  
Fluorinated Graphene

scholarly journals Study on Tribological Properties and Mechanisms of Different Morphology WS2 as Lubricant Additives

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1522 ◽  
Author(s):  
Ningning Hu ◽  
Xiuheng Zhang ◽  
Xianghui Wang ◽  
Na Wu ◽  
Songquan Wang
Keyword(s):  
Wear Resistance ◽  
Optimum Condition ◽  
Lubricating Oil ◽  
Stribeck Curve ◽  
Extreme Pressure ◽  
Friction Process ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Better Than

In the present work, the relationship curve of the coefficient of friction (COF) with varying loads of different morphology WS2 lubricating additives in the friction process at various sliding speeds was studied. On this basis, wear marks and elements on the wear surfaces after friction were analyzed, and then the anti-wear and mechanism effects of WS2 of different forms in the lubrication process were discussed. Meanwhile, the Stribeck curve was used to study the lubrication state of the lubricating oil in the friction process. It was revealed that the COF of lubricating oil containing lamellar WS2 decreased by 29.35% at optimum condition and the minimum COF was concentrated at around 100 N. The COF of lubricating oil containing spherical WS2 decreased by 30.24% and the minimum coefficient was concentrated at 120 N. The extreme pressure property of spherical WS2 was better than that of lamellar WS2, and the wear resistance of spherical WS2 was more stable when the load was over 80 N. The different morphology of WS2 additives can play anti-wear and anti-friction roles within a wide range of sliding speeds.

Molecular Dynamics Simulations of Sliding Friction of Rigid Sphere with Single Crystal Copper Surface

2013 ◽  
Vol 345 ◽  
pp. 167-171 ◽  
Author(s):  
Xiao Jing Yang ◽  
Xiao Jiang Yang
Keyword(s):  
Single Crystal ◽  
Sliding Friction ◽  
Normal Force ◽  
Three Dimensional ◽  
Copper Surface ◽  
Friction Model ◽  
Rigid Sphere ◽  
Stick Slip ◽  
Friction Process ◽  
Single Crystal Copper

Using LAMMPS to establish the three-dimensional sliding friction model of the nanoscale diamond hemisphere with the single-crystal copper surface. Simulation and solving the process of sliding friction, research the micro-contact area atomic states change in sliding friction process, and study the friction characteristics change when the rigid sphere sliding on rough surface of the single crystal copper with minute projections. The results indicate that, in the sliding friction process, the lattice of substrate atoms are damaged under the forces of the extrusion which also cause corresponding dislocation and deformation. In the direction of the hemisphere movement, generate the pileup and side stream phenomena, and produce furrows. Friction and normal force rapidly increase with the depth of contact, and then enter into a stable sliding phase. For the thermal motion of atoms, formation of dislocations and the stick-slip effect, the curves of friction and normal force present waves of sawtooth. Small defect on surface of the substrate almost have no effect on the process of sliding friction.

Simulations on Sliding Process between Si-DLC and DLC Films on a Water-Lubricated Condition

2010 ◽  
Vol 29-32 ◽  
pp. 1408-1413 ◽  
Author(s):  
Hui Qing Lan ◽  
Can Liu ◽  
Takahisa Kato
Keyword(s):  
Sliding Friction ◽  
Md Simulations ◽  
Low Friction ◽  
Wear Performance ◽  
Friction Process ◽  
The Past ◽  
Significant Interest ◽  
Lubrication Layer ◽  
Higher Temperature ◽  
Silicon Doped

Diamond like carbon (DLC) films have been extensively studied over the past decades due to their unique combination of properties, in particular, silicon-doped DLC (Si-DLC) films are of significant interest for tribological effects, they had a very low friction coefficient and possess the potential to improve wear performance in humid atmospheres and at higher temperature. But many experimental results of the Si-DLC films showed that their tribological properties changed greatly on different silicon contents. In the paper, molecular dynamics (MD) simulations were used to study a sliding friction process between Si-DLC and DLC films on an un-lubricated and a water-lubricated condition respectively. The results have been shown that a transfer film between the Si-DLC and DLC films was formed on the un-lubricated condition. In contrast, a boundary lubrication layer was found on the water-lubricated condition. Moreover, the friction force on the un-lubricated condition was larger than those on the water-lubricated condition.

The Influence of Temperature and Shear Rate on the Viscosity of Selected Motor Oils

2013 ◽  
Vol 199 ◽  
pp. 188-193 ◽  
Author(s):  
Adam Czaban
Keyword(s):  
Diesel Engine ◽  
Shear Rate ◽  
Sliding Friction ◽  
Full Range ◽  
Lubricating Oil ◽  
Initial Structure ◽  
Oil Viscosity ◽  
Lubricating Oils ◽  
Shear Rates ◽  
Motor Oils

One of the most important physical quantities which has an influence on bearings and micro-bearings functioning is the viscosity of a lubricant. The data about a viscosity value dependence on temperature and shear rate are essential for designing sliding friction pairs. In design calculations usually there is assumed that a lubricant is a Newtonian fluid, therefore viscosity is constant over the full range of shear rates. During operation of friction pairs the contamination particles get into a lubricant and this causes that the lubricant becomes a non-Newtonian pseudoplastic or viscoelastic fluid. A similar effect on lubricating oil properties have combustion products or special performance additives. Furthermore, a lubricating oil ages and wears out, i.e. during its operating the initial structure of a particles is destroyed which can cause the change of the oil viscosity and lubricity values. The aim of this work is to determine the dynamic viscosity values in dependence on temperature and shear rate for selected new and used lubricating oils. In this research motor oils for passenger vehicles and tractors were investigated. This paper presents the results of measurements of the viscosity changes, in dependence on shear rate and temperature, made for the new and used oils. One of the investigated oils is Superol CC-40, which was used in four-stroke 4562 cm3 diesel engine for twenty months, which corresponds to 250 hours of operating. The second of investigated oils is Shell Helix Ultra AV-L which was used in four-stroke 2000 cm3 diesel engine for ten months at a distance of 15 000 kilometers. The viscosity measurements for the new and used lubricating oils were made with the Thermo Scientific Haake Mars III rheometer, in the range of temperatures from 10°C to 120°C and of shear rates to 51000 1/s. Moreover, the analysis of wear products, contaminants and additives in the investigated new and used lubricating oils was made with the rotating disc electrode atomic emission spectrometer Spectro Incorporated Spectroil Q100, which gives possibility to determine 22 most common elements which occur in motor, turbine and gear oils. The obtained information will be used in future studies related to hydrodynamic lubrication of slide bearings and micro-bearings. It also may be useful for designing bearings and sliding friction pairs.

scholarly journals Adequate Force Characteristics of a Friction System

2013 ◽  
Vol 13 ◽  
pp. 20-36
Author(s):  
Zdzisław Pluta ◽  
Tadeusz Hryniewicz
Keyword(s):  
Sliding Friction ◽  
Static Friction ◽  
The Body ◽  
Friction Process ◽  
New Knowledge ◽  
Mechanical Behaviours ◽  
Adequate Definition ◽  
Definition Of ◽  
Inertia Forces ◽  
Force Characteristics

In the paper, at first some remarks concerning friction are presented by the definition of the friction itself, as well as its essential force characteristics. An adequate definition of friction is introduced, and moreover a correct its characteristics. Next the statics, dynamics, and kinematics of the friction system is given, forming the force characteristics of this system for each of the mechanical behaviours, taking into account real inertia forces of the body under friction. Three types of coefficients of sliding friction have been separated, namely: coefficient of static friction, dynamic friction, and kinematic friction. Then the comparative analysis of existent and new knowledge on the force characteristics of friction process has been presented. The consideration on how to determine the coefficient of static friction has also been carried out. Reflections on the possibilities to form further force characteristics of the friction process are presented to develop this work with some final remarks directing the attention on the conditions of development of science on friction.

scholarly journals DESCRIPTIVE MODEL OF SLIDING FRICTION PROCESSES

2015 ◽  
Vol 2 ◽  
pp. 227
Author(s):  
Andris Martinovs ◽  
Vladimir Gonca
Keyword(s):  
Friction Coefficient ◽  
Surface Area ◽  
Contact Surface ◽  
Sliding Friction ◽  
Friction Model ◽  
Friction Process ◽  
Contact Surface Area ◽  
Optimal Surface ◽  
Sliding Friction Coefficient ◽  
The Mathematical Model

Paper analyses the sliding friction coefficient of rubber on concrete, timber and ceramic tile surfaces depending on the weight of the sliding object and contact surface area. It has been established that increase in the weight of the object makes sliding friction coefficient to grow. In the case of increase in size of contact area, sliding friction coefficient between rubber and concrete also increases, but it decreases between rubber- timber and rubber- tile. The mathematical model for description of sliding friction process has been developed which can be used to determine optimal surface area and a pattern as well as optimal weight of the sliding object in order to provide sufficient sliding friction. Model has five independent constants. It includes the contact surface area, the weight and the velocity of the sliding object, sliding friction coefficient, temperature and time.

scholarly journals Dry Sliding Friction of Tool Steels and Their Comparison of Wear in Contact with ZrO2 and X46Cr13

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2359
Author(s):  
Michal Krbata ◽  
Maros Eckert ◽  
Lenka Bartosova ◽  
Igor Barenyi ◽  
Jozef Majerik ◽  
...  
Keyword(s):  
Sliding Friction ◽  
Process Analysis ◽  
Cutting Tools ◽  
High Strength Steels ◽  
High Strength ◽  
Sample Surface ◽  
Tool Steels ◽  
Friction Process ◽  
Working Cycle ◽  
The Impact

Tool steels are used in stamping, shearing processes, and as cutting tools due to their good mechanical properties. During their working cycle, steels are subject to aggressive conditions such as heat stress, fatigue, and wear. In this paper, three tool steels, namely X153CrMoV12, X37CrMoV5-1, and X45NiCrMo4 were selected against two types of bearing balls, ZrO2 and X46Cr1. All measurements were performed on a UMT TriboLab universal tribometric instrument under dry conditions. The main objective of the experiment was to analyze and compare tool steel wear in contact with two kinds of bearing balls with a diameter of 4.76 mm. This evaluation is focused on the hardness, surface roughness, and microstructure of all samples and on the impact of the input parameters on the resulting wear. All three types of tool steels were measured in the basic annealed state and, subsequently, in the state after hardening and tempering. Experimental results show that tool steels, belonging to high strength steels, can successfully represent wear resistant steels. The content of carbide elements, their size, and shape in the microstructure play an important role in the friction process and subsequent wear. Three types of loads were used and compared in the experiments 30, 60, and 90 N. Increasing the load results in significant degradation of the material on the sample surface. Lastly, the impact of hardness and roughness of materials on wear has also been proven. If abrasive wear occurs in the friction process, there is a greater degree of wear than that of adhesive wear. This is due to less abrasive particles, which behave like a cutting wedge and are subject to subsequent deformation strengthening due to the load increase, which adversely affects the further friction process. Analysis of the results showed that the ZrO2 ceramic ball showed significantly better wear values when compared to the X46Cr13 stainless steel ball. It also improves the values of the coefficient of friction with respect to the type of wear that occurs when the experimental materials and counterparts are in contact.

A Review of the Research on the Influencing Factors of Lubrication Performance for Sliding Bearings

2021 ◽  
Vol 16 ◽  
Author(s):  
Xiaodong Yu ◽  
Shiwei Zhan ◽  
Dianbin Huang ◽  
Fan Sun ◽  
Fakun Wang ◽  
...  
Keyword(s):  
Influencing Factors ◽  
High Speed ◽  
Sliding Friction ◽  
Working Environment ◽  
Research Progress ◽  
Lubricating Oil ◽  
Stable Operation ◽  
Sliding Bearings ◽  
Sliding Bearing ◽  
Lubrication Performance

Background: Sliding bearing is a kind of bearing that works under sliding friction, which has the characteristics of stable operation, safety and reliability and noiseless. With the technological progress of the machinery industry, modern machinery and equipment is developing in the direction of high speed and heavy load, its power is getting higher and higher, and the working environment is getting worse, so plain bearings are more and more widely used. Objective: In order to improve the lubricating performance of sliding bearings, the influencing factors of lubricating performance of sliding bearings are summarized and commented. Methods: The research progress and achievements at home and abroad are summarized from three aspects: influencing factors of lubrication performance of radial sliding bearings, thrust sliding bearings and influencing factors of lubricating oil on lubrication performance of sliding bearings, which provides reference for the future development of sliding bearings. Results: The study discusses the experimental method, simulation process and experimental results of the factors affecting the lubrication performance of sliding bearing. Conclusion: The texture, deformation, surface morphology of oil cavity, eccentric load and flow state of sliding bearings all affect the lubricating performance of sliding bearings, and lubricating oil also affects the lubricating performance of sliding bearings.

Online infrared spectra detection of lubricating oil during friction process at high temperature

2018 ◽  
Vol 70 (7) ◽  
pp. 1294-1302 ◽  
Author(s):  
Yongliang Jin ◽  
Haitao Duan ◽  
Lei Wei ◽  
Song Chen ◽  
Xuzheng Qian ◽  
...  
Keyword(s):  
High Temperature ◽  
Friction Coefficient ◽  
Infrared Spectra ◽  
Isothermal Holding ◽  
Lubricating Oil ◽  
Critical Transition ◽  
Friction Process ◽  
Content Type ◽  
Low Speed ◽  
Infrared Spectrometer

Purpose This paper aims to investigate the tribological behavior and online infrared spectra of three types of lubricating oils containing dinonyl diphenylamine (DNDA) antioxidant, which are mineral oil (MO), poly alpha olefin (PAO) and trimethylolpropane trioleate (TMPTO), during the friction process at high temperature (temperature rising at first and isothermal holding afterwards). Design/methodology/approach A platform of low speed four-ball tribometer equipped with a temperature controller combined with infrared spectrometer was established. MO, PAO and TMPTO base oils were mixed with 1.0 Wt.% DNDA antioxidant, coded as MOa, PAOa and TMPTOa in sequence. The friction coefficient and online infrared spectra of the oils were tested during the friction process of temperature rising at first and isothermal holding afterwards, and the wear tracks of the upper balls were measured using a confocal scanning optical microscope. Findings The results indicated that the DNDA antioxidant was depleted to reduce the generation of alcohols and carbonyl products, and the depletion rate of DNDA followed the sequence of MOa > PAOa > TMPTOa. In the temperature rising friction process, the critical transition of friction coefficient was confirmed. The addition of DNDA antioxidant reduced the temperature of the oils at the critical transition of friction coefficient, and the temperature followed the sequence of TMPTOa > PAOa > MOa. After the critical transition, the friction coefficient was first increased and then declined to a steady value; the friction coefficient of MOa increased and declined first, followed by PAOa and TMPTOa. In the steady stage of friction, there was no obvious effect of DNDA on the friction coefficient of the oils. Moreover, DNDA enhanced the wear properties of MOa and PAOa; no obvious improvement was revealed for the wear property of TMPTOa. Originality/value The established platform of low speed four-ball tribometer combined with infrared spectrometer successfully realized online testing of the structure changes of lubricating oil during high temperature friction, which can give some reference on the oxidation and friction researches of lubricating oil.

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