scholarly journals Ultralow Boundary Lubrication Friction by Three-Way Synergistic Interactions among Ionic Liquid, Friction Modifier, and Dispersant

2020 ◽  
Vol 12 (14) ◽  
pp. 17077-17090 ◽  
Author(s):  
Weimin Li ◽  
Chanaka Kumara ◽  
Huimin Luo ◽  
Harry M. Meyer ◽  
Xin He ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Boundary Lubrication ◽  
Boundary Lubrication Friction ◽  
Friction Modifier ◽  
Synergistic Interactions

Tribochemical Interactions of Friction Modifier and Antiwear Additives With CrN Coating Under Boundary Lubrication Conditions

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
T. Haque ◽  
A. Morina ◽  
A. Neville ◽  
S. Arrowsmith
Keyword(s):  
Boundary Lubrication ◽  
Photoelectron Spectroscopy ◽  
Antiwear Additives ◽  
Low Friction ◽  
Friction Modifier ◽  
Crn Coating ◽  
Atomic Force ◽  
Surface Analysis Techniques ◽  
Positive Effect ◽  
Lubrication Conditions

In recent years, the optimized use of low friction nonferrous coatings under boundary lubrication conditions has become a challenge to meet the demands of improved fuel economy in automotive applications. This study presents the tribological performance of chromium nitride (CrN) coating using conventional friction modifier (moly dimer) and/or antiwear additive (zinc dialkyl dithiophosphate (ZDDP)) containing lubricants in a pin-on-plate tribometer. Using surface analysis techniques such as the atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), both topographical and chemical analyses of tribofilms were performed. This paper shows that ZDDP and moly dimer both give a positive effect for both low friction and antiwear performance in CrN/cast iron system. Both AFM and XPS analyses give evidence of the formation of ZDDP and moly dimer derived tribofilms on the CrN coating and thus support friction and wear results.

scholarly journals Interfacial Structure and Boundary Lubrication of a Dicationic Ionic Liquid

Langmuir ◽  
2019 ◽  
Vol 35 (48) ◽  
pp. 15444-15450 ◽  
Author(s):  
Carla S. Perez-Martinez ◽  
Susan Perkin
Keyword(s):  
Ionic Liquid ◽  
Boundary Lubrication ◽  
Interfacial Structure ◽  
Dicationic Ionic Liquid

A Boundary Lubrication Friction Model Sensitive to Detailed Engine Oil Formulation in an Automotive Cam/Follower Interface

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Rupesh Roshan ◽  
Martin Priest ◽  
Anne Neville ◽  
Ardian Morina ◽  
Xin Xia ◽  
...  
Keyword(s):  
Boundary Lubrication ◽  
Fuel Efficiency ◽  
Lubricant Additive ◽  
Friction Model ◽  
Operating Conditions ◽  
Valve Train ◽  
Engine Oil ◽  
Contact Friction ◽  
Boundary Lubrication Friction ◽  
Base Oil

Theoretical studies have shown that in severe operating conditions, valve train friction losses are significant and have an adverse effect on fuel efficiency. However, recent studies have shown that existing valve train friction models do not reliably predict friction in boundary and mixed lubrication conditions and are not sensitive to lubricant chemistry. In these conditions, the friction losses depend on the tribological performance of tribofilms formed as a result of surface–lubricant additive interactions. In this study, key tribological parameters were extracted from a direct acting tappet type Ford Zetec SE (Sigma) valve train, and controlled experiments were performed in a block-on-ring tribometer under conditions representative of boundary lubrication in a cam and follower contact. Friction was recorded for the tribofilms formed by molybdenum dithiocarbamate (MoDTC), zinc dialkyldithiophosphate (ZDDP), detergent (calcium sulfonate), and dispersant (polyisobutylene succinimide) additives in an ester-containing synthetic polyalphaolefin (PAO) base oil on AISI E52100 steel components. A multiple linear regression technique was used to obtain a friction model in boundary lubrication from the friction data taken from the block-on-ring tribometer tests. The model was developed empirically as a function of the ZDDP, MoDTC, detergent, and dispersant concentration in the oil and the temperature and sliding speed. The resulting friction model is sensitive to lubricant chemistry in boundary lubrication. The tribofilm friction model showed sensitivity to the ZDDP–MoDTC, MoDTC–dispersant, MoDTC–speed, ZDDP–temperature, detergent–temperature, and detergent–speed interactions. Friction decreases with an increase in the temperature for all ZDDP/MoDTC ratios, and oils containing detergent and dispersant showed high friction due to antagonistic interactions between MoDTC–detergent and MoDTC–dispersant additive combinations.

Boundary Lubrication and Its Stability

2008 ◽  
Author(s):  
Kamaljit Singh ◽  
Saurabh Baghmar ◽  
Jagdish Sharma ◽  
M. V. Khemchandani ◽  
Q. J. Wang
Keyword(s):  
Solid Surface ◽  
Boundary Lubrication ◽  
Surface Forces ◽  
Aluminum Surface ◽  
Boundary Lubrication Friction ◽  
Lennard Jones ◽  
Boundary Lubricant ◽  
Zone Of Influence ◽  
En 31 ◽  
Experimental Values

The interaction between lubricant molecules and the solid surface to be lubricated depends upon the surface forces which can be attractive, and repulsive. It thus forms an interactive zone above the solid surface having a band width and height of surface potential and is considered as ‘Zone of Influence’-(ZOI). Its value will vary with the nature of surface finish, distribution of alloying constituents on surface matrix and its size which play very important role in prediction of stability and failure of boundary lubrication friction including absorption and desorption of lubricant molecules. A theoretical model for the formation of boundary lubrication is proposed by combining Lennard Jones (6–12) potential to incorporate for estimating the critical temperature of boundary lubricant, friction coefficient and variation of ZOI for a given condition. Experimental values using EN 31 Ball sliding against the aluminum surface with 0.4% stearic acid as lubricant data agrees well with theoretical values.

How much mixed/boundary friction is there in an engine — and where is it?

2019 ◽  
Vol 234 (10) ◽  
pp. 1563-1579 ◽  
Author(s):  
RI Taylor ◽  
N Morgan ◽  
R Mainwaring ◽  
T Davenport
Keyword(s):  
Boundary Lubrication ◽  
Mixed Boundary ◽  
Operating Conditions ◽  
Valve Train ◽  
Friction Modifier ◽  
Direct Measurements ◽  
Full Discussion ◽  
Engine Friction ◽  
The Individual ◽  
The Impact

Automotive engines are believed to operate predominantly in the hydrodynamic regime, as evidenced by the (1) the successful strategy of reducing lubricant viscosity to reduce engine friction and improve vehicle fuel consumption, and (2) for most engine operating conditions, direct measurements of engine friction (either motored or fired) find that engine friction increases with increasing engine speed. However, certain components in an engine are known to operate mainly in the mixed/boundary lubrication (e.g. the valve train) and other components (such as the piston rings) operate in the mixed/boundary regime for a portion of the time. In order to quantify the amount of mixed/boundary lubrication in an engine, and in the individual components of the engine, motored and fired friction tests have been carried out for a range of lubricants (of differing viscosity grade, and with/without friction modifier additives). A full discussion of the implications of this work, which includes the impact of fuel dilution and “running-in” is included with insights given into how the work reported here guides the development of future fuel-efficient engine lubricants.

Effect of friction coefficient on the mixed lubrication model of rotary lip seals

2019 ◽  
Vol 234 (11) ◽  
pp. 1746-1754
Author(s):  
Bingqi Jiang ◽  
Xing Huang ◽  
Fei Guo ◽  
Xiaohong Jia ◽  
Yuming Wang
Keyword(s):  
Numerical Calculation ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Dry Friction ◽  
Friction Torque ◽  
Mixed Lubrication ◽  
Test Method ◽  
Boundary Lubrication Friction ◽  
Pumping Rate ◽  
Lip Seals

This study is devoted to the effect of different coefficients on the calculation results of the rotary lip seal mixed lubrication model. It was proved by experiments that the dry friction coefficient used in the previous models was quite different from the boundary lubrication friction coefficient, which was theoretically more accurate. The pumping rate, friction torque, pressure distribution, and oil film thickness were calculated using both the dry friction coefficient and the boundary lubrication coefficient and the results were quite different. A friction coefficient test method under boundary lubrication condition for numerical simulation of rotary lip seals and an improved method for numerical calculation using the boundary lubrication coefficient instead of the dry friction coefficient were proposed. It was verified that the accuracy of numerical calculation can be improved, and the calculation result was closer to the actual working state.

A low-viscosity ionic liquid demonstrating superior lubricating performance from mixed to boundary lubrication

Wear ◽  
2013 ◽  
Vol 301 (1-2) ◽  
pp. 740-746 ◽  
Author(s):  
Gregory Mordukhovich ◽  
Jun Qu ◽  
Jane Y. Howe ◽  
Scott Bair ◽  
Bo Yu ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Boundary Lubrication ◽  
Low Viscosity
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