The effect of density and surface topography on the coefficient of friction of polytetrafluoroethylene films

MRS Advances ◽  
2020 ◽  
Vol 5 (54-55) ◽  
pp. 2753-2762
Author(s):  
Mathew Brownell ◽  
Arun K. Nair
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Film Surface ◽  
Coarse Grained ◽  
Dynamics Model ◽  
Ptfe Film ◽  
Mesh Structure ◽  
Particle Spacing ◽  
The Coefficient Of Friction ◽  
Chain Lengths

AbstractPolytetrafluoroethylene (PTFE) film is observed to increase surface roughness during annealing. Longer annealing times leads to greater surface roughness. The coefficient of friction of PTFE film is affected by the shape of microscale sized particles on the film surface. In this study, we investigate the coefficient of friction of PTFE films using a coarse-grained molecular dynamics model based on experimental observations. We observe how the variation in PTFE chain length and film density affect the topography of PTFE films. We also investigate how these properties of PTFE, and the indenter radius affect the coefficient of friction observed during surface scratch. We find that short PTFE chain lengths create a dense film with greater particle spacing, but longer chains form a mesh structure which reduces the density and creates overlapping portions of particles in the film. We develop a convolutional neural network to classify PTFE film surface and predict the coefficient of friction of a modeled film based solely on the equilibrated film topography. The accuracy of the network was seen to increase when the density and images of internal fiber orientation were added as input features. These results indicate that the coefficient of friction of PTFE films in part is governed by the internal structure of the film.

scholarly journals Experimental analysis of the surface roughness in the coefficient of friction test

2019 ◽  
Vol 41 ◽  
pp. 153-160
Author(s):  
Roque Calvo ◽  
Roberto D’Amato ◽  
Emilio Gómez ◽  
Alessandro Ruggiero
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Experimental Analysis ◽  
Friction Test ◽  
The Coefficient Of Friction

SURFACE MODIFICATION OF TPR SOLE: AN APPROACH TO IMPROVE SLIP RESISTANCE ON QUARRY AND CERAMIC TILES

2015 ◽  
Vol 88 (1) ◽  
pp. 163-175 ◽  
Author(s):  
R. Mohan ◽  
S. Raja ◽  
G. Saraswathy ◽  
B. N. Das
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Modification ◽  
Surface Treatment ◽  
Coefficient Of Friction ◽  
Chemical Surface ◽  
Resistance Property ◽  
Slip Resistance ◽  
The Coefficient Of Friction ◽  
Trichloroisocyanuric Acid

ABSTRACT Human slip on smooth surfaces is a common accident, even though the footwear soling materials are designed with cleats and treads to provide more friction with the floor. About 20% of footwear is made with thermoplastic rubber (TPR; styrene-butadiene-styrene) soles. The slip resistance property under wet-flooring conditions of this kind of sole is poor because of the nonionic nature of the polymer. Chemical surface modification can be exploited to improve the slip-resistance property of TPR soles. The surface is chemically modified with trichloroisocyanuric acid in a methyl ethyl ketone medium (TCI/MEK; at 1, 2, and 3%) to introduce chlorinated and oxidized moieties to the rubber surface. The extent of surface modification produced in TPR with this change can be tested using attenuated total reflectance–Fourier transform infrared spectroscopy, scanning electron microscopy, and contact angle and surface roughness measurements. The improvement in slip resistance can be evaluated by measuring the coefficient of friction using a dynamic slip-resistance tester. The extent of the change in the functional physical properties, such as surface roughness, contact angle, work adhesion, in slip resistance can be improved by optimizing the concentration of trichloroisocyanuric acid. Physicomechanical properties of unmodified and modified soles that are essential for wear performance can be tested and compared. Quantitative changes on the surface of modified rubber soles increases surface roughness, reduces contact angles, and increases work energy, so there is a considerable increase in the coefficient of friction, especially under wet floor conditions. The chemical surface treatment tends to reduce the bulk mechanical properties, such as tensile strength, elongation at break, and abrasion resistance, because cyanuric acid attacks the sole. The coefficient of friction produces a positive trend at 1 and 2% TCI/MEK treatments, but the trend is negative at a 3% concentration. The optimum surface treatment level for surface modification to enhance the slip resistance of TPR is 2% TCI/MEK.

The Influence of Surface Roughness on the Mechanism of Friction

1970 ◽  
Vol 92 (2) ◽  
pp. 264-272 ◽  
Author(s):  
T. Tsukizoe ◽  
T. Hisakado
Keyword(s):  
Surface Roughness ◽  
Metal Surface ◽  
Coefficient Of Friction ◽  
Dry Friction ◽  
Metal Surfaces ◽  
Roughness Effects ◽  
Real Area Of Contact ◽  
The Coefficient Of Friction ◽  
Tangential Forces ◽  
Soft Metal

A study was made of surface roughness effects on dry friction between two metals, assuming that the asperities are cones of the slopes which depend on the surface roughness. The theoretical explanations were offered for coefficients of friction of the hard cones and spheres ploughing along the soft metal surface. A comparison of calculated values based on these with experimental data shows good agreement. Moreover, theoretical discussion was carried out of surface roughness effects on dry friction between two metal surfaces on the basis of the analyses of the frictional mechanism for a hard slider on the metal surface. The theoretical estimation of the coefficient of friction between two metal surfaces can be carried out by using the relations between the surface roughness and the slopes of the asperities, and the coefficient of friction due to the adhesion at the interface. The experiments also showed that when two metal surfaces are first loaded normally and then subjected to gradually increasing tangential forces, real area of contact between them increases and the maximum tangential microslip of them increases with the increase of the surface roughness.

Influence of Surface Roughness on Friction and Contact Resistance in Sliding Electrical Contacts

2007 ◽  
Author(s):  
Dinesh G. Bansal ◽  
Jeffrey L. Streator
Keyword(s):  
Surface Roughness ◽  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Electrical Contact ◽  
Electrical Current ◽  
Electrical Contacts ◽  
Sliding Electrical Contacts ◽  
The Coefficient Of Friction ◽  
Current Densities

An experiment is conducted to investigate the role of surface roughness on the coefficient of friction and contact resistance of sliding electrical contacts. A hemispherical pin is sliding along both smooth and rough 2-meter rail surface. Tests are performed at both low and moderate sliding speed and for a range of electrical current densities, ranging from 0 to about 12 GA/m2. It was found that surface roughness had a significant influence on the coefficient of friction, with the smoother surfaces exhibiting higher coefficients of friction. Contact resistance, on the other hand, did not show as strong an effect of surface roughness, except for a few parameter combinations. At the higher current densities studied (>10 GA/m2), it was found that the contact resistance values tended to be on the order of 1 mΩ, independent of load, speed and roughness. This convergence may be due to presence of liquid metal film at the interface, which established ideal electrical contact.

Predicting the Coefficient of Friction in Sliding-Rolling Contacts

1989 ◽  
Vol 111 (2) ◽  
pp. 386-390 ◽  
Author(s):  
Yufeng Li ◽  
Ali Seireg
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Thermal Regime ◽  
Surface Coating ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Published Data ◽  
Excellent Correlation ◽  
Rolling Contacts ◽  
The Coefficient Of Friction

This paper deals with the development of a dimensionless empirical formula for calculating the coefficient of friction in sliding-rolling steel on steel contacts under different operating conditions in the thermal regime. The effect of lubrication, surface roughness, and surface coating on friction are considered. The formula shows excellent correlation with the experimental tests conducted by many investigators and provides a unified relationship for all the published data.

The Surface Roughness of a Rubber Soling Material Determines the Coefficient of Friction on Water-Lubricated Surfaces

1998 ◽  
Vol 29 (4) ◽  
pp. 275-283 ◽  
Author(s):  
Derek P Manning ◽  
Carla Jones ◽  
Frederick James Rowland ◽  
Martin Roff
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
The Coefficient Of Friction

Brush Dynamics: Models and Characteristics

2006 ◽  
Author(s):  
Libardo V. Vanegas Useche ◽  
Magd M. Abdel Wahab ◽  
Graham A. Parker
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Rotational Speed ◽  
Surface Finishing ◽  
Stick Slip ◽  
Street Sweeping ◽  
The Coefficient Of Friction ◽  
Dynamics Models ◽  
Frictional Behaviour ◽  
Duct Cleaning

This paper reviews investigations into the dynamics and modelling of brushes. They include brushes for surface finishing operations, removal of fouling, post-CMP brushing processes, air duct cleaning, and street sweeping. The methods that have been proposed to model brush dynamics are described, and the results of the research into brush mechanics are presented and discussed. Some conclusions of the paper are as follows: brush dynamics is very complex, as it depends on the interaction among many phenomena and variables. The bristle oscillations that occur in some brushes constitute a complexity for modelling brush behaviour and are not normally addressed. Additionally, the literature reveals that the coefficient of friction is not a constant value that depends only on the materials and surface roughness of the two contacting bodies. Frictional behaviour strongly depends on many variables, such as brush setup angles and rotational speed, which play a part in the development of stick-slip friction cycles. Finally, it is concluded that brush behaviour and the phenomena involved in brushing have not been fully studied or understood and more research into this field is needed.

The Use of Tertiary-Butyl-Hydroquinone (TBHQ) in Minimizing Oxidation Effects on Palm Oil Based Lubricant Using Four Ball Tribotester

2016 ◽  
Vol 819 ◽  
pp. 484-488 ◽  
Author(s):  
Samion Syahrullail ◽  
Paiman Zulhanafi
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Palm Oil ◽  
Mineral Oil ◽  
Wear Scar ◽  
Wear Scar Diameter ◽  
Tertiary Butyl ◽  
Oil Resources ◽  
The Coefficient Of Friction ◽  
Anti Oxidant

The extended uses of mineral oil based lubricant have continuously troubling the global environment issues. The remaining mineral oil resources also being the most debated issues in renewable energy conferences. Vegetable oils are still offering the highest possibility in replacing the mineral oil resources. This research is concerning on how to eliminate one of the disabilities found in palm oil based lubricant which is oxidation. Palm oil possessed unsaturated double bond in which susceptible to oxidation process. The simplest approach is to blend the palm oil based with anti – oxidant agent homogenously. This research was conducted using double fractionated palm oil (SPL) as lubricant and Tertiary-Butyl-Hydroquinone (TBHQ) as anti – oxidant agent to determine the tribology behavior including the coefficient of friction, wear scar diameter and the surface roughness profile. The experiment was also conducted using four-ball tribotester by following ASTM D4172B standard. Superior Mineral Engine Oil (EO) was used as comparison. The results found that SPL+TBHQ was able to reduce the coefficient of friction and provided lower surface roughness value. However it was unable to minimize the mean wear scar diameter compared to EO. The physical appearances of wear worn are also being observed in this research.

Influence of Material Internal Stresses to the Coefficient of Friction

2014 ◽  
Vol 604 ◽  
pp. 79-82
Author(s):  
Didzis Rags ◽  
Andris Kamols ◽  
Oskars Linins ◽  
Irina Boiko
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Internal Stresses ◽  
The Coefficient Of Friction

The aim of this paper is to calculate and compare both tangential and normal internal stresses in contacting area of two spherical bodies in contact. The results of these calculations have a practical use in further research of coefficient of friction in relation to the surface roughness asperities of contacting bodies.

Thermal EHL Analysis of Circular Contacts With Measured Surface Roughness

1996 ◽  
Vol 118 (3) ◽  
pp. 473-482 ◽  
Author(s):  
Gang Xu ◽  
Farshid Sadeghi
Keyword(s):  
Surface Roughness ◽  
Coefficient Of Friction ◽  
Three Dimensional ◽  
Time Dependent ◽  
The Coefficient Of Friction ◽  
Contact Surfaces ◽  
Energy Equations ◽  
Thermal Ehl ◽  
Circular Contact ◽  
Ehl Contact

Time dependent thermal EHL circular contact results with measured surface roughness were obtained to analyze the effects of roughness on pressure, film thickness, temperature, and coefficient of friction. Both contact surfaces are considered to be rough. Multilevel multigrid techniques (with multigrid integration) were used to solve the system of two dimensional Reynolds, elasticity and three dimensional energy equations simultaneously. The effects of surface roughness under various loads, speeds, and slip conditions have been studied. Surface roughness causes pressure and temperature spikes and increases the coefficient of friction, and surface roughness flattens due to the high pressure in EHL contact. The higher the load, speed and slide to roll ratio, the more significant the effect of the surface roughness. A comparison between rough EHL and smooth EHL results indicates that surface roughness cannot be ignored in EHL analysis.

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