scholarly journals Tribological Properties of Metal V-Belt Type CVT Lubricant

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Keiichi Narita
Keyword(s):  
Friction Coefficient ◽  
Film Formation ◽  
Antiwear Additives ◽  
Surface Analysis Techniques ◽  
Lubricant Formulation ◽  
Boundary Lubricant ◽  
Wet Clutch ◽  
Torque Capacity ◽  
Lubricant Performance ◽  
Insight Into

The priority for lubricant performance for metal V-belt-type CVT (B-CVTFs) should be the improvement of transmittable torque capacity between the belt and pulley plus excellent antishudder properties for lockup clutch used in B-CVTs. This study intends to investigate the effect of lubricant additives for improving these performances of B-CVTs. In addition, surface analysis techniques were utilized to gain a novel insight into the chemical composites and morphology of the tribofilms. As a result, it is vital for greater torque capacity to give higher boundary friction coefficient between the metal contacting interfaces, and the process of boundary lubricant film formation derived from antiwear additives used in B-CVTFs strongly impacts on the torque capacity. Moreover, it is found that a sort of lubricant formulation gave an excellent antishudder performance for wet clutch with keeping higher friction coefficient between the metals, which would result in improving the performance of B-CVTs.

Friction Characteristics and Topography of Tribofilms From Anti-Wear Additives Applied to Metal V-Belt Type CVT Fluids

2007 ◽  
Author(s):  
K. Narita ◽  
M. Priest
Keyword(s):  
Friction Coefficient ◽  
Film Formation ◽  
Positive Outcome ◽  
Antiwear Additives ◽  
Contact Mode ◽  
Hydrogen Phosphite ◽  
Metal Metal ◽  
Zinc Dithiophosphate ◽  
Sliding Test ◽  
The Individual

This study has investigated the metal-meal friction properties and the topography of tribochemical films derived from antiwear additives for application to metal-V-belt pushing type continuously variable transmission fluids (B-CVTFs). The influence of metal-metal tribological properties of various kinds of anti-wear additives were evaluated using a ball on plate tribometer, enabling lubricant film formation to be monitored during a reciprocating sliding test. In addition, contact mode atomic force microscope (AFM) was used to characterize the nature of the tribofilms at the namometre scale. For zinc-dithiophosphate (ZnDTPs), significant differences were observed in the friction coefficients and the topographic images between secondary and aryl type ZnDTP. The films derived from secondary type exhibit large solid pads, 5–30μm in length elongated in the sliding direction while the aryl type forms films in streaks on the ridges, with 8% higher friction coefficient than the secondary ZnDTP. Notably, the combination of over-based calcium sulphonate and hydrogen phosphite demonstrated a synergism with 8% higher friction coefficient and more stable film formation than the individual cases, providing a positive outcome for a BCVTF. Tribofilm species produced by a chemical reaction between hydrogen phosphite and over-based calcium sulphonate were densely deposited on the rubbing tracks, exhibiting rougher surfaces than those observed in the individual cases, consequently with a higher friction coefficient. These results suggest that the friction properties between metal-metal contacting surfaces strongly depend on the morphology of tribofilms derived from lubricant additives.

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

scholarly journals Comparison Between the Action of Nano-Oxides and Conventional EP Additives in Boundary Lubrication

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 54
Author(s):  
Valdicleide Silva Mello ◽  
Marinalva Ferreira Trajano ◽  
Ana Emilia Diniz Silva Guedes ◽  
Salete Martins Alves
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Friction And Wear ◽  
Film Formation ◽  
Environmental Issues ◽  
Protective Film ◽  
Extreme Pressure ◽  
Extreme Pressure Additives ◽  
Environmental Requirements ◽  
Lubrication Conditions

Additives are essential in lubricant development, improving their performance by the formation of a protective film, thus reducing friction and wear. Some such additives are extreme pressure additives. However, due to environmental issues, their use has been questioned because their composition includes sulfur, chlorine, and phosphorus. Nanoparticles have been demonstrated to be a suitable substitute for those additives. This paper aims to make a comparison of the tribological performance of conventional EP additives and oxides nanoparticles (copper and zinc) under boundary lubrication conditions. The additives (nanoparticles, ZDDP, and sulfur) were added to mineral and synthetic oils. The lubricant tribological properties were analyzed in the tribometer HFRR (high frequency reciprocating rig), and during the test, the friction coefficient and percentual of film formation were measured. The wear was analyzed by scanning electron microscopy. The results showed that the conventional EP additives have a good performance owing to their anti-wear and small friction coefficient in both lubricant bases. The oxides nanoparticles, when used as additives, can reduce the friction more effectively than conventional additives, and displayed similar behavior to the extreme pressure additives. Thus, the oxide nanoparticles are more environmentally suitable, and they can replace EP additives adapting the lubricant to current environmental requirements.

scholarly journals Experimental Study on the Transition between Static and Kinetic Frictions of Steel/Shale Pairs

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qin Lian ◽  
Chunxu Yang ◽  
Jifei Cao
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Critical Distance ◽  
Dynamic Friction ◽  
Stick Slip ◽  
Dynamic Friction Coefficient ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Stick Slip Motion ◽  
Insight Into

The transition between static and kinetic frictions of steel/shale pairs has been studied. It was found that the coefficient of friction decreased exponentially from static to dynamic friction coefficient with increasing sliding displacement. The difference between static and dynamic friction coefficients and the critical distance Dc under the dry friction condition is much larger than that under the lubricated condition. The transition from static to dynamic friction coefficient is greatly affected by the normal load, quiescent time, and sliding velocity, especially the lubricating condition. Maintaining continuous lubrication of the contact area by the lubricant is crucial to reduce or eliminate the stick-slip motion. The results provide an insight into the transition from static to dynamic friction of steel/shale pairs.

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.

Evaluation of Polymers as Lubricants in the Extrusion of Aluminum

1982 ◽  
Vol 104 (4) ◽  
pp. 552-557 ◽  
Author(s):  
S. Suresh ◽  
S. Bahadur
Keyword(s):  
Yield Criterion ◽  
Film Formation ◽  
Normal Pressure ◽  
Velocity Fields ◽  
Powder Particle Size ◽  
Extrusion Force ◽  
Polymer Powder ◽  
Von Mises ◽  
Insight Into

The lubricating behavior of polytetrafluoroethylene, polyvinyl chloride, polychlorotrifluoroethylene, low density polyethylene, and high density polyethylene powders in the extrusion of 1100-0 aluminum has been investigated in terms of the extrusion force requirement and the quality of extrudate surface finish. Extrusion experiments which provided a measure of the extrusion force and friction force with varying ram travel were performed under both ambient and high temperature conditions. From these data the variation of coefficient of friction with ram travel and normal pressure has been calculated using the analysis based on von Mises’ yield criterion and spherical velocity fields. The effect of polymer powder particle size on the extrusion force was investigated. The extrudate surfaces were examined by scanning electron miscroscopy in order to study the film formation capability of polymers and to get an insight into the mechanism of polymer lubrication.

scholarly journals Chemical and physical origins of friction on surfaces with atomic steps

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw0513 ◽  
Author(s):  
Zhe Chen ◽  
Arash Khajeh ◽  
Ashlie Martini ◽  
Seong H. Kim
Keyword(s):  
Friction Coefficient ◽  
Relative Motion ◽  
Single Layer ◽  
Chemical Processes ◽  
Single Layer Graphene ◽  
Atomic Steps ◽  
Layer Graphene ◽  
Lateral Forces ◽  
Physical And Chemical ◽  
Insight Into

Friction occurs through a complex set of processes that act together to resist relative motion. However, despite this complexity, friction is typically described using a simple phenomenological expression that relates normal and lateral forces via a coefficient, the friction coefficient. This one parameter encompasses multiple, sometimes competing, effects. To better understand the origins of friction, here, we study a chemically and topographically well-defined interface between silica and graphite with a single-layer graphene step edge. We identify the separate contributions of physical and chemical processes to friction and show that a single friction coefficient can be separated into two terms corresponding to these effects. The findings provide insight into the chemical and topographic origins of friction and suggest means of tuning surfaces by leveraging competing frictional processes.

Evaluation of the frictional properties of an elastomer with enhanced lipid-adsorbing ability

1997 ◽  
Vol 211 (5) ◽  
pp. 359-368 ◽  
Author(s):  
P F Williams ◽  
Y Iwasaki ◽  
K Ishihara ◽  
G L Powell ◽  
J A Gilbert ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Particle Production ◽  
Film Formation ◽  
Wear Particle ◽  
Load Bearing ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Elastomeric Bearing ◽  
Boundary Lubricant ◽  
Major Factors ◽  
Static Coefficient Of Friction

Wear particle production in load-bearing orthopaedic implants is one of the major factors currently limiting the service life of the implant. Most of the research carried out to date in attempting to solve this problem has used the approach of finding more wear-resistant biocompatible material pairs. In contrast, other researchers have attempted to reduce wear by encouraging elastohydrodynamic film formation through the use of elastomeric bearing surfaces. Unfortunately, these elastomeric bearing surfaces have poor tribological properties when a fluid film is not present. Boundary lubrication of an elastomeric orthopaedic bearing may alleviate some of these difficulties. The purpose of this research was to fabricate and characterize an elastomeric material that had a surface capable of specifically adsorbing a naturally occurring boundary lubricant. Dipalmitoyl phosphatidylcholine (DPPC) has been previously shown to be able to act as a boundary lubricant at stresses that occur in human load-bearing joints such as the hip and knee; therefore, DPPC was chosen for use in this study. It was expected that in an aqueous liposome suspension the static coefficient of friction μs of such a material would be lower, and increase less quickly over time, than a similar material without an ability to adsorb specifically DPPC when articulated against a polished chrome steel ball bearing. The lipid-adsorbing elastomer did not possess the desired tribological properties. This result was attributed to the polymer adsorbing the DPPC in the liposome phase and not in the bilayer phase, and interaction among the polymeric surface, DPPC and water. This approach to lubricating orthopaedic bearings was shown to have some merit, but a great deal of work needs to be done before such an approach can be used on a clinically available material.

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