Newly synthesized Ionic Liquids as potent lubricants and additives to existing lubricant oils

2021 ◽  
pp. 135065012110601
Author(s):  
Thomas Myrdek ◽  
Michael Stapels ◽  
Werner Kunz
Keyword(s):  
Ionic Liquids ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Alkyl Ether ◽  
Tribological Behaviour ◽  
Low Friction ◽  
Low Performance ◽  
Long Chain ◽  
Anionic Part

Ionic Liquids are promising candidates for next generation green lubricants. We have synthesized 39 Tetraalkylammonium Alkyl Ether Carboxylate Ionic Liquids and tested them for their lubricant capabilities. We measured friction coefficient to assess the transition from the boundary to the hydrodynamic lubrication, the hydrodynamic area and the minimum friction value. Some Ionic Liquids are capable of forming a hydrodynamic layer fully separating two specimens. Compounds with short C-chain of the cationic part show poor tribological behaviour. Similarly, increasing the PO-degree of the anionic part lowers the lubrication power. An increase of the C-chain length improves the tribological behaviour, i.e. the minimum friction value becomes lower. This is due to the formation of a uniform tribolayer of the long-chain carboxylic acids. Higher viscosity of the Ionic Liquids results in low friction coefficients and the development of a hydrodynamic layer. This is due to a strong hydrodynamic pressure, which is formed by the more viscous compound. Addition of small amounts of Ionic Liquids to low performance oils increases their capability to from tribolayers and thus improves their lubricant capability.

Prediction of Wear Rate Dispersion in Mixed Lubrication

2005 ◽  
Author(s):  
F. Robbe-Valloire ◽  
R. Progri ◽  
B. Paffoni ◽  
R. Gras
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Boundary Lubrication ◽  
Mixed Lubrication ◽  
Tribological Behaviour ◽  
Low Friction ◽  
Local Boundary ◽  
Physico Chemical ◽  
Lubricant Films ◽  
Second Category

Mixed lubrication is usually related to the partition of contacts, and these latter may be divided into two categories. The first includes all asperities working in thin lubricated film (physico-chemical film) conditions. This situation corresponds to local boundary lubrication and is characterised by a local friction coefficient around 0.1. The second category contains all other asperity types. Due to the existence of a thick lubricant films asperities belonging to the second category exhibit a low friction coefficient. The global tribological behaviour for a given contact, however, is function of both categories, since it involves asperities from both categories.

Tribological behaviour of graphene oxide sheets as lubricating additives in bio-oil

2018 ◽  
Vol 70 (8) ◽  
pp. 1396-1401 ◽  
Author(s):  
Daoyi Wu ◽  
Yufu Xu ◽  
Lulu Yao ◽  
Tao You ◽  
Xianguo Hu
Keyword(s):  
Graphene Oxide ◽  
Friction Coefficient ◽  
Wear Loss ◽  
Tribological Behaviour ◽  
Low Friction ◽  
Content Type ◽  
Base Oil ◽  
Lubricating Film ◽  
Bio Oil ◽  
Practical Implications

Purpose This paper aims to study the upgradation of the lubricating performance of the renewable base oil , and to study the tribological behavior of graphene oxide (GO) sheets used as lubricating additives in bio-oil for iron/steel contact. Design/methodology/approach A multifunctional end-face tribometer was used to characterize the friction coefficient and wear loss of the tribosystem under different lubricants. Findings The experimental results show that GO sheets with small size benefit lubricating effects and the optimal concentration of GO sheets in bio-oil is 0.4-0.6 per cent, which can form a complete lubricating film on the frictional interfaces and obtain a low friction coefficient and wear loss. Higher concentration of GO sheets can result in a significant aggregation of the sheets, reducing the content of the lubricating components in the bio-oil, which results in the increase in friction and wear; at this stage, the main wear pattern was ascribed to adhesive wear. Practical implications These results show a promising prospect of improving the tribological performance of renewable base oil with the introduction of GO sheets as additives. Originality/value No literature has covered the tribological behaviour of GO sheets in bio-oil. This study contributes to accelerating the application of bio-oil.

Improvement of Tribological Behaviors by Optimizing Concave Texture Shape Under Reciprocating Sliding Motion

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Hui Zhang ◽  
Guang-neng Dong ◽  
Meng Hua ◽  
Kwai-Sang Chin
Keyword(s):  
Friction Coefficient ◽  
Hydrodynamic Pressure ◽  
Low Friction ◽  
Reciprocating Sliding ◽  
Contour Maps ◽  
Major Mechanism ◽  
Tribological Behaviors ◽  
Sliding Motion ◽  
Light Load ◽  
Experimental Comparisons

An analytical numerical model to optimize the shape of concave surface texture for the achievement of low friction in reciprocating sliding motion has been developed. The model uses: (i) average Reynolds equation to evaluate friction coefficient and (ii) genetic algorithm (GA) to optimize and obtain several preferable texture shapes. Analysis of distribution contour maps of hydrodynamic pressure gives the possible mechanisms involved. Moreover, experimental comparisons of tribological performances between the optimized and the circular textures were conducted to verify the simulation results. It is shown that surface textures of the elliptical and fusiform shapes can effectively enhance the load bearing capacity and reduce the friction coefficient compared with circular textures. The increase in hydrodynamic pressure for these optimized texture shapes is considered to be the major mechanism responsible for improving their tribological performance. Experimental results confirm that the elliptical-shaped textures have preferable tribological behaviors of low friction coefficient under the operating condition of light load.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

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