Pristine and Alkylated MoS2 Nanosheets for Enhancement of Tribological Performance of Paraffin Grease Under Boundary Lubrication Regime

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Sooraj S. Rawat ◽  
A. P. Harsha ◽  
Deepak P. Agarwal ◽  
Sangita Kumari ◽  
Om P. Khatri
Keyword(s):  
Coefficient Of Friction ◽  
Tribological Performance ◽  
Wear Volume ◽  
Mos2 Nanosheets ◽  
Lubricating Grease ◽  
Metal Soap ◽  
Paraffin Oil ◽  
Lubrication Regime ◽  
The Coefficient Of Friction ◽  
Worn Surface

In the present study, lubricating grease was developed with paraffin oil and 12-lithium hydroxy stearate metal soap as a thickening agent. MoS2 nanosheets were synthesized by hydrothermal method and functionalized with 1-octadecanethiol (i.e., MoS2-ODT). The MoS2 and MoS2-ODT nanosheets were dispersed in the grease with different concentrations to evaluate its tribological performance. Tribological results unveiled that the addition of MoS2 nanosheets in grease appreciably reduced the coefficient of friction and mean wear volume of tribo-interfaces as compared with pure grease. Energy dispersive spectroscopy (EDS) spectrum revealed the deposition of MoS2 on the worn surface and confirmed a thin tribo-film which protects steel tribo-pair against wear.

Study of Tribological Properties of Multilayer Ti/TiN Coating Containing Stress Absorbing Layers

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Amod Kashyap ◽  
A. P. Harsha ◽  
Harish C. Barshilia ◽  
Venkataramana Bonu ◽  
Praveen Kumar V. ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Wear Behavior ◽  
Multilayer Coating ◽  
Considerable Change ◽  
Wear Volume ◽  
Significant Drop ◽  
X Ray ◽  
Paraffin Oil ◽  
The Coefficient Of Friction ◽  
Steel Balls

Abstract Titanium (Ti)/titanium nitride (TiN) ultrathin multilayer coating was deposited on 100Cr6 substrates to investigate the friction and wear behavior in the presence of paraffin oil as a lubricant. The coating architecture was designed by adding thick stress absorbing layers (SAL ∼320 nm) in between the ultrathin Ti/TiN (3.5/4 nm) multilayer structure. The SAL reduces the residual stress in the coating. The coating had a NaCl type of structure, and X-ray diffraction (XRD) results showed the preferential crystallographic orientation of TiN along [111] direction. The tribological properties of the nanostructured coating were evaluated under reciprocating sliding conditions at varying loads (2 and 7 N), and temperature (30 and 100 °C) against 100Cr6 steel balls using paraffin oil as a lubricant. There was no considerable change in the coefficient of friction (COF) at different testing parameters. However, there was a significant drop in wear volume at high-temperature testing conditions. The worn tracks were analyzed for their morphology and elemental composition through scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), and Raman spectroscopy.

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.

scholarly journals Fretting wear rate of sulphur deficient MoSx coatings based on dissipated energy

2001 ◽  
Vol 16 (12) ◽  
pp. 3567-3574 ◽  
Author(s):  
Xiaoling Zhang ◽  
W. Lauwerens ◽  
L. Stals ◽  
Jiawen He ◽  
J-P. Celis
Keyword(s):  
Relative Humidity ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Ambient Air ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Wear Volume ◽  
The Coefficient Of Friction ◽  
Crystallographic Orientations

The fretting wear of sulphur-deficient MoSx coatings with different crystallographic orientations has been investigated in ambient air of controlled relative humidity. The coefficient of friction and the wear rate of MoSx coatings sliding against corundum depend not only on fretting parameters like contact stress, fretting frequency, and relative humidity, but also strongly on the crystallographic orientation of the coatings. For randomly oriented MoSx coatings, the coefficient of friction and the wear rate increased significantly with increasing relative humidity. In contrast, basal-oriented MoSx coatings were less sensitive to relative humidity. The coefficient of friction of both types of MoSx coatings decreased on sliding against corundum with increasing contact stress and decreasing fretting frequency. A correlation between dissipated energy and wear volume is proposed. This approach allows detection in a simple way of differences in fretting wear resistance between random- and basal-oriented MoSx coatings tested in ambient air of different relative humidity.

Finite element analysis of fretting wear considering variable coefficient of friction

2018 ◽  
Vol 233 (5) ◽  
pp. 758-768 ◽  
Author(s):  
Ling Li ◽  
Le Kang ◽  
Shiyun Ma ◽  
Zhiqiang Li ◽  
Xiaoguang Ruan ◽  
...  
Keyword(s):  
Finite Element ◽  
Coefficient Of Friction ◽  
Variable Coefficient ◽  
Friction Model ◽  
Slip Condition ◽  
Fretting Wear ◽  
Partial Slip ◽  
Wear Volume ◽  
The Coefficient Of Friction ◽  
Contact Surfaces

Fretting wear is a kind of material damage in contact surfaces caused by microrelative displacement between two bodies. It can change the profile of contact surfaces, resulting in loosening of fasteners or fatigue cracks. Finite element method is an effective method to simulate the evolution of fretting wear process. In most studies of fretting wear, the coefficient of friction was assumed to be constant to simplify model and reduce the difficulty of solving. However, fretting wear test showed that the coefficient of friction was a variable related to the number of fretting cycles. Therefore, this paper introduces the coefficient of friction as a function of the number of fretting cycles in numerical simulation. A wear model considering variable coefficient of friction is established by combining energy consumption model and adaptive grid technique. The nodes of contact surfaces are updated through the UMESHMOTION subroutine. The effects of constant coefficient of friction and variable coefficient of friction on fretting wear are analyzed by comparing the wear amount under different loading conditions. The results show that when compared with coefficient of friction model, fretting wear is obviously affected by variable coefficient of friction and the variable coefficient of friction model has a larger wear volume when the fretting is in partial slip condition and mixed slip condition. In gross slip condition, the difference of wear volume between variable coefficient of friction model and coefficient of friction model decreases with the increase in the displacement amplitudes.

Analysis of the Contribution of Adhesion and Ploughing to Shoe-Floor Lubricated Friction in the Boundary Lubrication Regime

2011 ◽  
Author(s):  
Caitlin Moore ◽  
Kurt Beschorner ◽  
Pradeep L. Menezes ◽  
Michael R. Lovell
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Ambient Conditions ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Material Hardness ◽  
Lubrication Layer ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Pin On Disk

Slip and fall accidents cost billions of dollars each year. Shoe-floor-lubricant friction has been shown to follow the Stribeck effect, operating primarily in the boundary and mixed-lubrication regimes. Two of the most important factors believed to significantly contribute to shoe-floor-lubricant friction in the boundary lubrication regime are adhesion and ploughing. Experiments were conducted using a pin-on-disk tribometer to quantify adhesion and ploughing contributions to shoe-floor friction in dry and lubricated conditions. The coefficient of friction between three shoe materials and two floor materials of different hardness and roughness were considered. Experiments were conducted under six lubricants for a sliding speed of 0.01 m/sec at ambient conditions. It was found that the contribution of adhesion and ploughing to shoe-floor-lubricant friction was significantly affected by material hardness, roughness, and lubricant properties. Material hardness and roughness are known to affect adhesion, with increased hardness or increased roughness typically resulting in decreased adhesion. The smoothest shoe material, while also being the hardest, resulted in the greatest adhesional contribution to friction. The roughest material, while also being the softest, resulted in the lowest adhesional contributions under dry conditions. Canola oil consistently resulted in the lowest percent of full adhesion and water consistently resulted in the highest percent of full adhesion, presumably due to the thickness, of the boundary lubrication layer. Ploughing contribution was dependent upon the hardness of the shoe and floor materials. A positive correlation was found between the shoe and floor hardness ratio and ploughing coefficient of friction.

Cr doped MoS2 films: Tribological Properties, Microstructure and Electronic Structure

2021 ◽  
pp. 1-13
Author(s):  
Jian Liu ◽  
Xudong Sui ◽  
Zhen Yan ◽  
Guosheng Huang ◽  
Junying Hao
Keyword(s):  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Tribological Performance ◽  
Wear Volume ◽  
Chemical Compositions ◽  
Cross Sectional ◽  
X Ray ◽  
Wear Life ◽  
Target Power ◽  
Worn Surface

Abstract Cr doped MoS2 films were deposited by magnetron sputtering. The tribological properties of Cr doped MoS2 films under vacuum (VC) and air (AR) environments were investigated. The results show that Cr doped MoS2 film with Cr target power of 0.2 A (0.2 A Cr:MoS2 film) exhibits low friction coefficient and long wear life under both VC and AR environments. The chemical compositions of the films were analyzed by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). With the increases of Cr target power, the content of Cr increases. The cross-sectional FESEM morphologies show that the structure of the films changed from granular particles to column when the Cr target power increases from 0.2A to 0.4A. The wear mechanism has also been discussed based on the characteristics of worn surface. The 0.4 A Cr:MoS2 film has the lowest wear volume among these films, which can be attributed to the compact microstructure. The bandgap of Cr doped MoS2 films were measured by XPS and the tribological performance of the film is found to be best when there is a modest bandgap. It can be speculated that the tribological performance of Cr doped MoS2 films are closely related to the width of bandgap.

scholarly journals Effect of Micro- and Nano-Sized Carbonous Solid Lubricants as Oil Additives in Nanofluid on Tribological Properties

Lubricants ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 25 ◽  
Author(s):  
Emad Omrani ◽  
Pradeep Menezes ◽  
Pradeep Rohatgi
Keyword(s):  
Coefficient Of Friction ◽  
Canola Oil ◽  
Friction And Wear ◽  
Solid Lubricants ◽  
Lubricating Oil ◽  
Oil Additives ◽  
Load Carrying ◽  
The Coefficient Of Friction ◽  
Pin On Disk ◽  
Worn Surface

The tribological behavior of graphene and graphite as additives in canola oil was investigated with a pin-on-disk tribometer. The wear surfaces of the aluminum pins lubricated with the additive-containing canola oil were analyzed by scanning electron microscopy (SEM). It was found that graphene and graphite as additives in oil show a lower coefficient of friction and wear rate in comparison with neat canola oil. The graphene sheets are more effective than graphite flakes to reduce friction and wear. In addition, there is a proper concentration where the coefficient of friction (COF) and wear are in minimum value. The optimal concentration of the additive in canola oil is about 0.7 wt %. Therefore, the load-carrying capacity and antiwear ability of the lubricating oil are improved. Moreover, the worn surface of aluminum pins is smother in the presence of solid lubricant rather than neat oil.

Influence of Surface Texture on Micro EHL in Boundary Regime Sliding

2012 ◽  
Author(s):  
Robert Erck ◽  
Oyelayo O. Ajayi ◽  
Cinta Lorenzo-Martin ◽  
George R. Fenske
Keyword(s):  
Thin Film ◽  
Coefficient Of Friction ◽  
Elastohydrodynamic Lubrication ◽  
Asperity Contact ◽  
Disc Surface ◽  
Lubrication Regime ◽  
Uncoated Steel ◽  
Constant Friction ◽  
The Coefficient Of Friction ◽  
Hydrogenated Amorphous

A hard steel ball was slid against textured coated and uncoated steel disks that had strongly directionally ground surfaces. The friction coefficient during ball-on-disk rotating low-speed lubricated sliding was continuously measured. The coefficient of friction rose from ≈ 0.12, which is typical for boundary lubrication regime, to as high as 0.45 whenever the ball was sliding parallel to the grinding ridges on the disc surface. The persistence of this “spike” in the friction was observed to be correlated with the hardness of the disc surface and the nature of the coating. We propose that the frictional spike is due to loss of micro-elastohydrodynamic lubrication, combined with side leakage, leading to intimate asperity-asperity contact. As a result, the coefficient of friction is close to that which is obtained there is no or minimal lubrication. This conclusion is supported by enhanced and persistent frictional spikes in tests conducted with discs coated with a very hard nitride thin film, and constant friction for a disk coated with hydrogenated amorphous carbon, which has low coefficient of friction when there is no/minimal lubrication.

Manufacture and Tribological Properties of C/C-SiC Brake Composites Fabricated by Warm Compacted In Situ Reaction

2010 ◽  
Vol 97-101 ◽  
pp. 1665-1668 ◽  
Author(s):  
Xiao Peng ◽  
Li Zhuan ◽  
Xiong Xiang
Keyword(s):  
Silicon Carbide ◽  
Wear Rate ◽  
Carbon Fibre ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Tribological Performance ◽  
Matrix Composites ◽  
The Coefficient Of Friction ◽  
Sic Composites

Carbon fibre reinforced carbon and silicon carbide dual matrix composites (C/C-SiC) were fabricated by warm compacted in-situ reaction. The C/C-SiC composites microstructure and tribological properties at different brake speeds were investigated. The results indicated that the composites were composed of 58 wt% C, 37 wt% SiC and 5 wt% Si. The density and open porosity were 2.0 g•cm-3 and 10%, respectively. The C/C-SiC brake composites show excellent tribological performance, including a good stability of brake, the coefficient of friction between 0.57 and 0.67, and the wear rate less than 2.02 cm3•MJ-1. These results show that the C/C-SiC brake composites are the promising candidates for advanced brake and clutch systems.

High Temperature Tribological Performance of Steel/Copper Friction Pairs Lubricated With a Modified C-WS2-(Fe3O4+TiN) Nanoadditives in Non-Copper Coated Solid Wires

2021 ◽  
Author(s):  
Hong Li ◽  
Jing Zhu ◽  
Yu Zhang ◽  
Zhuoxin Li ◽  
Bo Meng
Keyword(s):  
High Temperature ◽  
Friction And Wear ◽  
Ball Bearing ◽  
Tribological Performance ◽  
Wear Volume ◽  
Test Results ◽  
Nanoparticle Concentration ◽  
Tribological Test ◽  
Average Coefficient ◽  
Worn Surface

Abstract In this study, four kinds of nanoparticles: graphite, WS2, Fe3O4 and TiN were used as lubricating additives for steel/copper friction pairs to solve the problem of welding contact tube wear with non-copper-coated solid wire at high temperature. The single and composite nanoparticles have excellent dispersion stability in absolute ethanol under the action of the compound surfactant NaSTA+OA+PVP. The tribological test results showed that the maximum decrement with reference to the average coefficient of friction and wear volumes were measured with nanoparticle concentration in 1:1:1 ratio at 300℃. Compared with dry friction, the average friction coefficient and wear volume are reduced by 74.3% and 84.8%, respectively, which may be attributed to the formation of a stable tribo-film mainly composed of C-O, Fe2O3, WO3, TiO2, TiNxOy composite on the worn surface. Therefore, it is considered that the combined lubrication effects of the ball-bearing effect, repairing of worn surfaces and the tribo-film resulted in the lowest friction and wear.

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