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.

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.

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 Green human resource management

2020 ◽  
Vol 41 (7) ◽  
pp. 1041-1060 ◽  
Author(s):  
Azadeh Shafaei ◽  
Mehran Nejati ◽  
Yusmani Mohd Yusoff
Keyword(s):  
Positive Outcome ◽  
Theory And Practice ◽  
Research Model ◽  
Online Questionnaire ◽  
Content Type ◽  
Individual Level ◽  
Study Approach ◽  
The Individual ◽  
Green Human Resource Management ◽  
Organisational Level

PurposeThe study aimed to provide insights on antecedent and outcome of green HRM at the organisational level and the outcome of green HRM at the individual level. It also sought to examine the mechanism through which green HRM would lead to employees’ positive outcome.Design/methodology/approachA quantitative study design using a two-study approach was employed to collect and analyse the data. For study 1, 206 hotels from Malaysia were included in analysis at the organisational level, while in study 2 at the individual level, 508 employees from different sectors provided insights through an online questionnaire. For both studies, partial least squares (PLS–SEM) was used to assess the research model.FindingsAll the proposed hypotheses were supported. Specifically, at the organisational level, organisational environmental culture is positively related to green HRM, and green HRM management positively associates with organisation's environmental performance. At the individual level, green HRM positively influences employees' job satisfaction, and meaningfulness through work is a strong mediator in this relationship.Originality/valueThis study is significant as it contributes to both theory and practice by providing fresh insights on green HRM and its antecedent and outcomes at two levels (organisational and individual) and across two economies (emerging and developed). It also sheds some light on the outcome of green HRM at the employee level which is an area that is still under-researched. By focusing on meaningfulness through work as an important factor, the study contributes to better understanding of green HRM and employees’ positive outcomes.

Effect of Applied DC Voltage to Stainless Steel Pin and CNx Coated Disk in Pin-on-Disk Sliding Test on Tribological Properties

2005 ◽  
Author(s):  
Noritsugu Umehara ◽  
Takahiro Yamamoto ◽  
Yoshio Fuwa
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Friction And Wear ◽  
The Other ◽  
Electric Voltage ◽  
Dc Voltage ◽  
Negative Voltage ◽  
Positive Voltage ◽  
Sliding Test ◽  
Pin On Disk

The effect of applied DC voltage on the friction and wear of CNx sliding against stainless steel pin in air was clarified. Friction coefficient decreased with the increasing negative voltage to apply to the ball and disk in air. On the other hand, positive voltage increased friction coefficient. Friction coefficient of CNx in air decreased from 0.22 to 0.05 by applying electric voltage of DC −200 V. Specific wear rate was decreased with the increasing applied positive and negative voltage. It was considered that the oxidation of CNx was controlled by electric field.

Switchable Friction Coefficient on Shape Memory Photonic Crystals

MRS Advances ◽  
2020 ◽  
Vol 5 (14-15) ◽  
pp. 757-763
Author(s):  
Yifan Zhang ◽  
Xingyi Lyu ◽  
Yongliang Ni ◽  
Diyang Li ◽  
Sin-Yen Leo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Photonic Crystal ◽  
Friction Coefficient ◽  
Photonic Crystals ◽  
Shape Memory ◽  
Intelligent Control ◽  
Surface Friction ◽  
Soft Robotics ◽  
Sliding Test ◽  
Sensor Interfaces

ABSTRACTIntelligent control of friction and adhesion has attracted much attention for use in soft robotics, human-sensor interfaces, and bionics. Here we introduce a shape memory photonic crystal (SMPC) polymer that can be programmed and recovered by solvent to realize switchable surface friction. Micro sliding test show that the friction coefficient on this SMPC in the programmed and recovered state can vary by three times. We also show that the mechanism behind this switchable friction coefficient is the surface roughness related adhesion.

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