The Difficulty of Measuring Low Friction: Uncertainty Analysis for Friction Coefficient Measurements

2005 ◽  
Vol 127 (3) ◽  
pp. 673-678 ◽  
Author(s):  
Tony L. Schmitz, ◽  
Jason E. Action, ◽  
John C. Ziegert, and ◽  
W. Gregory Sawyer
Keyword(s):  
Friction Coefficient ◽  
Uncertainty Analysis ◽  
Cell Voltage ◽  
Load Cell ◽  
International Standards ◽  
Voltage Measurement ◽  
Low Friction ◽  
Laboratory Procedure ◽  
Friction Measurements ◽  
Pin On Disk

The experimental evaluation of friction coefficient is a common laboratory procedure; however, the corresponding measurement uncertainty is not widely discussed. This manuscript examines the experimental uncertainty associated with friction measurements by following the guidelines prescribed in international standards. The uncertainty contributors identified in this analysis include load cell calibration, load cell voltage measurement, and instrument geometry. A series of 20 tests, carried out under nominally identical conditions, was performed using a reciprocating pin-on-disk tribometer. A comparison between the experimental standard deviation and uncertainty analysis results is provided.

The study of friction layer and tribological property of PI–matrix composites

2017 ◽  
Vol 69 (2) ◽  
pp. 267-275 ◽  
Author(s):  
Xiulin Xu ◽  
Xing Lu ◽  
Zuoxiang Qin ◽  
Dalong Yang
Keyword(s):  
Friction Coefficient ◽  
Tribological Property ◽  
Wear Debris ◽  
Friction Pair ◽  
Matrix Composites ◽  
Low Friction ◽  
Friction Layer ◽  
Content Type ◽  
Compact Zone ◽  
Pin On Disk

Purpose This paper aims to study the friction layer and tribological property of polyimide (PI)–matrix composites under different friction speeds. Design/methodology/approach Friction tests were conducted under friction speeds ranging from 20-120 km/h and pressure of 0.57 MPa by a pin-on-disk tribometer. Findings The results indicate that the friction coefficient decreases with the increasing of the friction speed. Under different friction speeds, the structure of the friction layer and debris are different, which affects the actual tribological performance of the composites. At low friction speed, the morphology of the friction layer is mainly particulate. The higher level of clenching action between the friction pair leads to a high friction coefficient, and the morphology of the particles in the particulate zone and the wear debris are mostly equiaxial particles. At high friction speed, the morphology of the friction layer is mainly a compact zone. The reduction of the surface roughness leads to a low friction coefficient. The debris collected on the counter surface at high friction speeds are mostly big sheets, and the morphology of the particles in the particulate zone is mostly rod-like. Controlling the conditions of the disk and the pin can reveal the influence of friction speed on the friction layer. The wear mechanisms at different friction speeds are also discussed. Originality/value By controlling the conditions of the disk and the pin to reveal the influence of friction speed on the friction layer, and the evolutions of the friction layer, wear debris were carefully inspected with the aim of demonstrating the relationship between friction speed and wear mechanism of PI–matrix composites.

Boundary Lubricated Friction Experiments With Coarse Surface Texture

2005 ◽  
Author(s):  
Jorn Larsen-Basse ◽  
Lewis Ives ◽  
Stephen M. Hsu
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Contact Area ◽  
Surface Texture ◽  
304 Stainless Steel ◽  
Low Friction ◽  
Partial Removal ◽  
Coarse Texture ◽  
Coarse Surface ◽  
Pin On Disk

Low-speed friction experiments were conducted under boundary lubrication in a pin-on-disk tester. The 304 stainless steel disk had smooth areas alternating with areas of coarse surface texture consisting of indents or macroscopic grooves, 0.3–0.4 mm in size and in area fractions varying between 25 and 70%. The 3.2 mm flat pin was also SS304. The coarse texture has detrimental effects. For each pattern the friction coefficient is greater than for the smooth areas. It becomes independent of load as boundary conditions set in. In comparing various patterns it is noted that this friction coefficient increases with pressure or with the amount of area removed to form the texture. It is suggested that partial removal of surface area to form the texture reduces the number of trapped liquid patches, which otherwise can provide low-friction load support. The coarse texture may also conduct lubricant away from the contact area.

A Computational Chemistry Approach for Investigation of Low Friction Mechanisms Based on FEP Film with Functionalized SiO2 Nanoparticles

2015 ◽  
Vol 1119 ◽  
pp. 142-150
Author(s):  
Yusuke Morita ◽  
Marleen de Weser ◽  
Gerhard Schottner
Keyword(s):  
Friction Coefficient ◽  
Internal Combustion Engines ◽  
Fuel Efficiency ◽  
Friction Reduction ◽  
Dynamics Simulation ◽  
Chemical Calculation ◽  
Combustion Engines ◽  
Low Friction ◽  
Reduction Mechanisms ◽  
Friction Measurements

To improve the fuel efficiency of automobile internal combustion engines, we investigated the fundamental mechanism of friction reduction within engine moving parts. A new coating was designed by introducing SiO2nanoparticles in FEP film. The SiO2nanoparticles were functionalized with hydrophobic fluoroalkyl units on their surface to create additional low friction property. Universal Surface Tester friction measurements revealed a significant reduction of the friction coefficient with increasing number of hydrophobic fluoroalkyl units for SiO2surface functionalization. To clarify the friction reduction mechanisms by the functionalization of SiO2nanoparticles, a quantum chemical calculation was carried out. The result indicates that an attractive force occurs between nanoparticle Si atoms and polymer F atoms, while by adding fluoroalkyl units on the SiO2nanoparticle surface, this force changes to repulsive. By performing a molecular dynamics simulation of a shear model between FEP film and SiO2nanoparticles, we observed a decrease of friction force with increasing fluoroalkyl units which lead smooth rolling motion of nanoparticles, thus confirming the repulsive effect of nanoparticle functionalization. We conclude that fluoroalkyl units on the SiO2surface play an important role in creating a repulsive force between nanoparticle and FEP film which lead to low friction coefficient.

Friction and wear of argon-implanted silicon crystals

1994 ◽  
Vol 9 (1) ◽  
pp. 91-95 ◽  
Author(s):  
J. Lekki ◽  
Z. Stachura ◽  
N. Preikschas ◽  
B. Cleff ◽  
M. Cholewa ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Single Crystals ◽  
Friction And Wear ◽  
Strong Influence ◽  
X Ray Diffraction ◽  
Low Friction ◽  
X Ray ◽  
Silicon Crystals ◽  
Xrd Techniques ◽  
Pin On Disk

Silicon 〈111〉 single crystals were implanted with 70 keV Ar ions to the dose of 1017 ions/cm2. Next, the friction coefficient between a Si crystal and a hard steel ball was measured using a pin-on-disk setup in air and in vacuum. The wear tracks were measured using a surface profilometer. For measurements performed in vacuum, a strong influence of implantation on friction force and wear tracks was found. The microstructure of the samples was subsequently investigated using RBS, ERD, and x-ray diffraction (XRD) techniques. Micro-RBS measurements showed that Ar had been removed from the wear tracks, despite their continued exhibition of low friction.

Mechanical and bio-lubricated friction performance of PA6G for gear applications

MRS Advances ◽  
2020 ◽  
Vol 5 (59-60) ◽  
pp. 3055-3064
Author(s):  
María T. Hernández-Sierra ◽  
Juan E. Marta ◽  
Luis D. Aguilera-Camacho ◽  
J.S. García-Miranda ◽  
José E. Báez-García ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Mechanical Performance ◽  
Low Friction ◽  
Mechanical And Tribological Properties ◽  
Hardness Tests ◽  
Friction Performance ◽  
Canola Oils ◽  
Pin On Disk ◽  
Chemical Groups ◽  
Potential Use

AbstractThe PA6G blue is a polymeric material for great versatility of engineering applications that required good mechanical and tribological properties such as gears. The focus of this study was to investigate the mechanical properties as well as the friction and wear resistance of a commercial PA6G blue under biodegradable external lubrication, to evaluate its potential use for gear applications. Firstly, the PA6G blue was characterized by FTIR analysis in order to identify the characteristic chemical groups of this polymer. The mechanical characterization was performed by tension and hardness tests according to the standards ASTM D638 and ASTM E10, respectively. Subsequently, friction tests were carried out on a tribometer with pin-on-disk configuration based on the ASTM G99 standard, in dry and lubricated conditions. Natural castor and canola oils were employed as bio-lubricants, as well as their mixture at 50% by volume. The results exhibited that the PA6G blue exhibit good mechanical performance as that required by gear fabrications. Besides, the friction performance showed a low friction coefficient of 0.11 in the dry condition that decreased about 50% in lubricated tests, obtaining a friction coefficient value of 0.054.

Microstructure and Friction of Ion Beam Induced Amorphous Ti-Pd Alloys

1985 ◽  
Vol 55 ◽  
Author(s):  
J-P. Hirvonen ◽  
M. Nastasi ◽  
J. R. Phillips ◽  
J. W. Mayer
Keyword(s):  
Solid Solution ◽  
Friction Coefficient ◽  
Composition Range ◽  
Ion Beam ◽  
Amorphous Region ◽  
Transmission Electron ◽  
Solid Solution Region ◽  
Friction Measurements ◽  
Solution Region ◽  
High Equilibrium

ABSTRACTMultilayered samples of Ti-Pd with linearly varying compositions were irradiated by Xe ions at 600 keV. The induced microstructures were studied by using transmission electron microscopy and Rutherford backscattering. Mixing was found to be complete over the entire composition range, resulting in amorphous or amorphous plus crystalline structures except at the palladium-rich end, where a crystalline Pd-Ti solid solution was obtained. This is consistent with the high equilibrium solubility of Ti in Pd. In addition, significant coarsening of the microstructure caused by irradiation was found in this solid solution region.Friction measurements were carried out in air and water by using a polytetrafluoroethylene pin as a counterpart. In air the friction coefficient was independent of composition and microstructure after about 2000 passes. In water, however, after 600 passes the friction coefficient reached a steady-state value with a pronounced minimum over the amorphous region. This property was unchanged throughout the remaining 10000 passes.

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