scholarly journals Tribological evaluation and lubrication mechanisms of nanoparticles enhanced lubricants in cold rolling

2020 ◽  
Vol 21 (1) ◽  
pp. 108
Author(s):  
Liang Hao ◽  
Zheng Wang ◽  
Guoyuan Zhang ◽  
Yangyang Zhao ◽  
Qingjuan Duan ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Friction Reduction ◽  
Base Oils ◽  
Lubrication Performance ◽  
Protective Films ◽  
The Coefficient Of Friction ◽  
20 Nm ◽  
Lubrication Mechanisms

Base oils containing different nanoparticles with varying concentrations are prepared, in which SiO2, TiO2 and ZnO (20 nm) nanoparticles are employed to improve the lubrication performance. Their tribological properties are evaluated on a ball-on-disk tribometer. The results show that the nano-additive lubricants exhibit a good friction reduction and anti-wear ability at the optimal concentration of 1.0 wt.%, in which SiO2 nanoparticles can reduce the coefficient of friction (COF) and the area of wear scar (AWS) by 45.6% and 35%, respectively. The SiO2 nanoparticles exhibit the best potential additive tested. The lubrication mechanisms of the nanoparticles can be attributed to the rolling, mending and the protective films.

The Effect of Nanoparticle Functionalization on Lubrication Performance of Nanofluids Dispersing Silica Nanoparticles in an Ionic Liquid

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Cengiz Yegin ◽  
Wei Lu ◽  
Bassem Kheireddin ◽  
Ming Zhang ◽  
Peng Li ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Coefficient Of Friction ◽  
Shear Thinning ◽  
Antiwear Additives ◽  
Functionalized Silica ◽  
Low Concentrations ◽  
Lubrication Performance ◽  
The Coefficient Of Friction ◽  
High Concentrations ◽  
Newtonian Behavior

Recently, ionic liquids (ILs) have received an increasing attention as lubricants owing to their intriguing properties such as tunable viscosity, high thermal stability, low emissions, nonflammability, and corrosion resistance. In this work, we investigate how the incorporation of octadecyltrichlorosilane (OTS) functionalized silica nanoparticles (NPs) in 1-butyl-3-methylimidazolium (trifluoromethysulfony)imide influences the tribological properties and rheological properties of IL under boundary lubrication and elastohydrodynamic conditions, respectively. It was found that the coefficient of friction was depended on the concentration of NPs in IL with a concave upward functional trend with a minimum at 0.05 wt.% for bare silica NPs and at 0.10 wt.% for OTS-functionalized silica NPs. For steel–steel sliding contact, the presence of functionalized NPs in IL at the optimum concentration decreased the coefficient of friction by 37% compared to IL and 17% compared to IL with bare silica NPs. While IL with bare NPs demonstrated a shear thinning behavior for all concentrations, IL with functionalized NPs showed a Newtonian behavior at low concentrations and shear thinning behavior at high concentrations. Overall, this study provides new insights into the antifriction and antiwear additives for lubrication systems involving ILs.

Paper 16: Friction in Wet Clutches

1967 ◽  
Vol 182 (14) ◽  
pp. 132-138 ◽  
Author(s):  
E. M. Evans ◽  
J. Whittle
Keyword(s):  
Coefficient Of Friction ◽  
Power Transmission ◽  
Sliding Speed ◽  
Friction Materials ◽  
Friction Characteristics ◽  
Sliding Surfaces ◽  
Base Oils ◽  
Wet Friction ◽  
Friction Clutch ◽  
The Coefficient Of Friction

This paper is intended to demonstrate that designers of wet clutches for power transmission can obtain the optimum friction characteristics for specific applications by considering the interaction between friction materials and lubricants. A friction clutch plate rig is described and the friction results obtained are presented. It is shown that a wide variation of coefficients of friction and frictional characteristics in wet friction clutches can be obtained by changing the oils and friction materials. In particular the coefficient of friction is dependent upon (1) the oil, (2) the materials of the sliding surfaces, (3) sliding speed, and (4) temperature. It is also shown that the coefficient of friction is affected by ( a) refining treatment given to the oil, ( b) different base oils, and ( c) additives.

scholarly journals The Effect of Elemental Composition and Nanostructure of Multilayer Composite Coatings on Their Tribological Properties at Elevated Temperatures

2020 ◽  
Author(s):  
Alexey Vereschaka ◽  
Sergey Grigoriev ◽  
Vladimir Tabakov ◽  
Mars Migranov ◽  
Nikolay Sitnikov ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Elevated Temperatures ◽  
Composite Coatings ◽  
Multilayer Composite ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Tribological Parameters ◽  
Adhesion Component

The chapter discusses the tribological properties of samples with multilayer composite nanostructured Ti-TiN-(Ti,Cr,Al,Si)N, Zr-ZrN-(Nb,Zr,Cr,Al)N, and Zr-ZrN-(Zr,Al,Si)N coatings, as well as Ti-TiN-(Ti,Al,Cr)N, with different values of the nanolayer period λ. The relationship between tribological parameters, a temperature varying within a range of 20–1000°C, and λ was investigated. The studies have found that the adhesion component of the coefficient of friction (COF) varies nonlinearly with a pronounced extremum depending on temperature. The value of λ has a noticeable influence on the tribological properties of the coatings, and the nature of the mentioned influence depends on temperature. The tests found that for the coatings with all studied values of λ, an increase in temperature first caused an increase and then a decrease in COF.

Tribological Properties of Polyoxymethylene Composites Against Aluminum

2003 ◽  
Vol 125 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Masaya Kurokawa ◽  
Yoshitaka Uchiyama ◽  
Tomoaki Iwai ◽  
Susumu Nagai
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
High Surface ◽  
Surface Hardness ◽  
Disk Surface ◽  
Optical Microscope ◽  
Transfer Film ◽  
The Other ◽  
The Coefficient Of Friction

Tribological properties of several kinds of polyoxymethylene (POM) composites were evaluated for the purpose of developing a polymeric tribomaterial especially suited for mating with aluminum parts having low surface hardness. POM composites containing small amounts of silicon carbide (SiC), POM/SiC; those containing a small amount of calcium octacosanonoate besides SiC, POM/SiC/Ca-OCA; and the one blended with 24 wt % of polytetrafluoroethylene, POM/PTFE(24); were injection-molded into pin specimens and their tribological properties were tested by means of a pin-on-disk type wear apparatus using an aluminum (A5056) mating disk in comparison with a 303 stainless steel (SUS303) disk. Evaluation was focused on observation of the sliding surfaces of the pin specimens and the mating disks by a scanning electron microscope and an optical microscope together with the measurement of surface roughness. In the case of mating against a SUS303 disk having high surface hardness, all pin specimens did not roughen the disk surfaces even after long time of rubbing. Only POM/PTFE(24) composite obviously made a transfer film on the disk surface, while the other composites made an extremely thin one on it. POM/SiC(0.1)/Ca-OCA(1) composite, containing SiC 0.1 wt. % and Ca-OCA 1 wt. %, was found to show the lowest coefficient of friction and the lowest wear rate forming extremely thin transfer film on the mating disk. On the other hand, against an A5056 disk which has lower surface hardness than that of SUS303 disk, unfilled POM and POM composites except POM/SiC(0.1)/Ca-OCA(1) composite roughened the disk surfaces. However, the sliding surface of the A5056 disk rubbed with POM/SiC(0.1)/Ca-OCA(1) composite was significantly smoother and that of the pin specimen was also quite smooth in comparison with other pin specimens. Further, when each POM composite was rubbed against the A5056 disk, formation of transfer film was not obvious on the disk surfaces. For POM/SiC(0.1)/Ca-OCA(1) composite, the wear rate was the lowest of all POM composites, and the coefficient of friction was as low level as 60 percent of that of unfilled POM, but slightly higher than that of POM/PTFE(24) composite. For POM/SiC(0.1)/Ca-OCA(1) composite, the nucleating effect of SiC and Ca-OCA, which accelerated the crystallization of POM during its injection molding to form a matrix containing fine spherulites, must have resulted in increasing the toughness of the matrix and lowering the wear rate. Also, the lubricant effect of Ca-OCA should have lowered the coefficient of friction of the same matrix for rubbing against aluminum mating disk. POM/SiC(0.1)/Ca-OCA(1) composite was concluded as an excellent tribomaterial for mating with aluminum parts.

Influence of Hydrodynamic Fluid Pressure and Shoe Tread Depth on Available Coefficient of Friction

2012 ◽  
Author(s):  
Gurjeet Singh ◽  
Kurt Beschorner
Keyword(s):  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Fluid Pressure ◽  
Hydrodynamic Pressure ◽  
High Viscosity ◽  
Health Concern ◽  
Fluid Viscosity ◽  
Low Viscosity ◽  
The Coefficient Of Friction ◽  
Lubrication Mechanisms

Slip and fall accidents are a major occupational health concern. Identifying the lubrication mechanisms affecting shoe-floor-contaminant friction under biofidelic (testing conditions that mimic human slipping) conditions is critical to identifying unsafe surfaces and designing a slip-resistant work environment. The purpose of this study is to measure the effects of varying tread design, tread depth and fluid viscosity on underfoot hydrodynamic pressure, the load supported by the fluid (i.e. load carrying capacity), and the coefficient of friction (COF) during a simulated slip. A single vinyl floor material and two shoe types (work shoe and sportswear shoe) with three different tread depths (no tread, half tread and full tread) were tested under two lubrication conditions: 1) 90% glycerol and 10% water (219 cP) and 2) 1.5% Detergent-98.5% (1.8cP) water solutions. Hydrodynamic pressures were measured with a fluid pressure sensor embedded in the floor and a forceplate was used to measure the friction and normal forces used to calculate coefficient of friction. The study showed that hydrodynamic pressure developed when high viscosity fluids were combined with no tread and resulted in a major reduction of COF (0.005). Peak hydrodynamic pressures (and load supported by the fluid) for the no tread-high viscous conditions were 234 kPa (200.5 N) and 87.63 kPa (113.3 N) for the work and sportswear shoe, respectively. Hydrodynamic pressures were negligible when at least half the tread was present or when a low viscosity fluid was used despite the fact that many of these conditions also resulted in dangerously low COF values. The study suggests that hydrodynamic lubrication is only relevant when high viscous fluids are combined with little or no tread and that other lubrication mechanisms besides hydrodynamic effects are relevant to slipping like boundary lubrication.

Some Tribological Properties of an Ionic Liquid

2005 ◽  
Author(s):  
Takashi Nogi
Keyword(s):  
Ionic Liquid ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Friction And Wear ◽  
Wear Performance ◽  
Lubrication Regime ◽  
Pin On Disc ◽  
The Coefficient Of Friction

Some tribological properties of an ionic liquid were investigated by using a pin-on-disc friction and wear tester. Due to running-in, the coefficient of friction of the ionic liquid decreased with time to a very low value of 0.02 which suggests that the lubrication regime was hydrodynamic at the end of the tests. Anti-wear performance of the ionic liquid was substantially comparable to a paraffin-based oil.

THE INFLUENCE OF GLASSY CARBON AND ITS FORMS ON TRIBOLOGICAL PROPERTIES OF ALUMINIUM MATRIX COMPOSITES

Tribologia ◽  
2019 ◽  
Vol 285 (3) ◽  
pp. 79-87 ◽  
Author(s):  
Jerzy MYALSKI ◽  
Andrzej Posmyk ◽  
Bartosz HEKNER ◽  
Marcin GODZIERZ
Keyword(s):  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Glassy Carbon ◽  
Amorphous Structure ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
Entire Volume ◽  
Carbon Particles ◽  
The Matrix ◽  
The Coefficient Of Friction

Carbon with an amorphous structure was used as a component to modify the tribological properties of engineering plastics. Its construction allows the formation of carbon-based wear products during friction, adhesively bonded to the surface of cooperating machine parts, acting as a solid lubricant. The work compares the tribological properties of two groups of composites with an aluminium alloy matrix in which glassy carbon appeared in the form of particles and an open cell foam fulfilling the role of strengthening the matrix. The use of spatial structures of reinforcement provides, in comparison with the strengthening of particles, homogeneity of carbon distribution in the entire volume of the composite. The tests carried out on a pin-disc tester showed that the use of spatial carbon structures in the composite ensures a greater coefficient of friction stability than when reinforcing with particles, and the coefficient of friction with a small proportion of carbon foams (about 1 wt%) is comparable with the coefficient of friction in the contact with composites containing 5-10% carbon particles in granular form.

Development of Antifriction Materials Based on Polytetrafluoroethylene with Carbon Fibers and Tungsten Disulfide

2020 ◽  
Vol 992 ◽  
pp. 745-750
Author(s):  
A.P. Vasilev ◽  
T.S. Struchkova ◽  
A.G. Alekseev
Keyword(s):  
Wear Resistance ◽  
Polymer Composites ◽  
Carbon Fibers ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Relative Elongation ◽  
Tungsten Disulfide ◽  
Degree Of Crystallinity ◽  
Mechanical And Tribological Properties ◽  
The Coefficient Of Friction

This paper presents the results from the investigation of effect the carbon fibers with tungsten disulfide on the mechanical and tribological properties of PTFE. Is carried out a comparison of mechanical and tribological properties of polymer composites PTFE-based with carbon fibers and PTFE with complex filler (carbon fibers with tungsten disulfide). It is shown that at a content of 8 wt.% CF+1 wt.% WS2 in PTFE, wear resistance increases significantly while maintaining the tensile strength, relative elongation at break and low coefficient of friction at the level of initial PTFE. The results of X-ray analysis and investigation of SEM supramolecular structure and friction surfaces of PTFE and polymer composites are presented. It is shown that the degree of crystallinity of polymer composites increases in comparison with the initial PTFE. The images of scanning electron microscope reveal that particles of tungsten disulfide concentrating on the friction surface is likely responsible to a reduction in the coefficient of friction and increase the wear resistance of PTFE-based polymer composites with complex fillers.

Friction Reduction in the Sliding of an Elastic Half-Space Against a Rigid Surface Due to Incident Rectangular Dilatational Waves

1999 ◽  
Vol 122 (1) ◽  
pp. 10-15 ◽  
Author(s):  
George G. Adams
Keyword(s):  
Normal Stress ◽  
Half Space ◽  
Coefficient Of Friction ◽  
Tangential Velocity ◽  
Elastic Half Space ◽  
Body Waves ◽  
Friction Reduction ◽  
Rigid Surface ◽  
Rectangular Wave ◽  
The Coefficient Of Friction

The steady sliding of a flat homogeneous and isotropic elastic half-space against a flat rigid surface, under the influence of incident plane dilatational waves, is investigated. The interfacial coefficient of friction is constant with no distinction between static and kinetic friction. It is shown here that the reflection of a harmonic wave under steady sliding consists of a pair of body waves (a plane dilatational wave and a plane shear wave) radiated from the sliding interface. Each wave propagates at a different angle such that the trace velocities along the interface are equal and supersonic. The angles of wave propagation are determined by the angle of the incident wave, by the Poisson’s ratio, and by the coefficient of friction. The amplitude of the incident waves is subject only to the restriction that the perturbations in interface contact pressure and tangential velocity satisfy the inequality constraints for unilateral sliding contact. It is also found that an incident rectangular wave can allow for relative sliding motion of the two bodies with a ratio of remote shear to normal stress which is less than the coefficient of friction. Thus the apparent coefficient of friction is less than the interface coefficient of friction. This reduction in friction is due to periodic stick zones which propagate supersonically along the interface. The influences of the angle, amplitude, and shape of the incident rectangular wave, the interfacial friction coefficient, the sliding speed, and of the remotely applied normal stress, on friction reduction are determined. Under appropriate conditions, the bodies can move tangentially with respect to each other in the absence of an applied shear stress. [S0742-4787(00)00201-0]

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