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Static friction of normal and reversed metal–polymer sliding pairs Cover

Static friction of normal and reversed metal–polymer sliding pairs

Materials Science-Poland
Volume 40 (2022): Issue 3 (September 2022)
By: Mariusz Opalka  
Open Access
|Mar 2023

Figures & Tables

Fig. 1

Variants of sliding pairs for materials characterised by different deformability [15]: variant I (normal sliding pair) – (1) polymer sample, (2) steel counter body; variant II (reversed sliding pair) – (1) steel sample, (2) polymer counter body
Variants of sliding pairs for materials characterised by different deformability [15]: variant I (normal sliding pair) – (1) polymer sample, (2) steel counter body; variant II (reversed sliding pair) – (1) steel sample, (2) polymer counter body

Fig. 2

Test stand for tribological investigations at reciprocating motion: (A) schematic, (B) photo of the test stand
Test stand for tribological investigations at reciprocating motion: (A) schematic, (B) photo of the test stand

Fig. 3

Average values of static friction coefficient of tested PEUHMW-C45 contact in normal and reversed sliding pair. PE-UHMW, Polyethylene with an ultrahigh molecular weight
Average values of static friction coefficient of tested PEUHMW-C45 contact in normal and reversed sliding pair. PE-UHMW, Polyethylene with an ultrahigh molecular weight

Fig. 4

Average values of static friction coefficient of tested POM-C45 contact in normal and reversed sliding pair. POM, polyoxymethylene
Average values of static friction coefficient of tested POM-C45 contact in normal and reversed sliding pair. POM, polyoxymethylene

Fig. 5

Average values of static friction coefficient of tested PTFE-C45 contact in normal and reversed sliding pair. PTFE, polytetrafluoroethylene
Average values of static friction coefficient of tested PTFE-C45 contact in normal and reversed sliding pair. PTFE, polytetrafluoroethylene

Fig. 6

Microscopic images of polymer samples' surface after friction tests. Red circles mark smeared (macrode-formed) material on the surface. SEM, magnification: ×400, topography BSD, 15 kV. PE-UHMW, Polyethylene with an ultrahigh molecular weight; POM, polyoxymethylene; PTFE, polytetrafluoroethylene
Microscopic images of polymer samples' surface after friction tests. Red circles mark smeared (macrode-formed) material on the surface. SEM, magnification: ×400, topography BSD, 15 kV. PE-UHMW, Polyethylene with an ultrahigh molecular weight; POM, polyoxymethylene; PTFE, polytetrafluoroethylene

Fig. 7

A phenomenon which takes place in friction pair's contact area: increase in contact surface due to material creep at rest under load over time ts, contributing to an increase in static friction force [20]
A phenomenon which takes place in friction pair's contact area: increase in contact surface due to material creep at rest under load over time ts, contributing to an increase in static friction force [20]

The static friction coefficient of tested polymer–steel friction pairs as a function of unit pressure p_ Normal sliding pairs

Sample materialUnit pressure p [MPa]
0.51.02.0
PE-UHMW0.10 ± 0.0020.09 ± 0.0010.08 ± 0.001
POM0.09 ± 0.0010.08 ± 0.0010.07 ± 0.001
PTFE0.05 ± 0.0010.06 ± 0.0010.05 ± 0.001

Percentage changes in static friction coefficient values for normal sliding pair in comparison with reversed pair

Unit pressure p [MPa]
0.512Average
PE-UHMW (%)−16.7−18.2−27.3−20.7
POM (%)−43.7−42.8−41.7−42.7
PTFE (%)−44.4−25.0−16.7−28.7

The static friction coefficient of tested steel-polymer friction pairs as a function of unit pressure p_ Reversed sliding pairs

Counterbody materialUnit pressure p [MPa]
0.51.02.0
PE-UHMW0.12 ± 0.0010.11 ± 0.0010.11 ± 0.001
POM0.16 ± 0.0020.14 ± 0.0020.12 ± 0.002
PTFE0.09 ± 0.0020.08 ± 0.0010.06 ± 0.001

Mechanical parameters of polymers selected for tests [18]

Density [g/cm3]E-modulus [MPa]Glass transition temperature [°C]Melting point [°C]Softening point [°C]
PE-UHMW0.93730−10013580
POM1.412400−240 to 180167150
PTFE2.6750−97327-
DOI: https://doi.org/10.2478/msp-2022-0040 | Journal eISSN: 2083-134X | Journal ISSN: 2083-1331
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Language: English
Page range: 152 - 159
Submitted on: Nov 4, 2022
Accepted on: Jan 9, 2023
Published on: Mar 3, 2023
Published by: Wroclaw University of Science and Technology
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
polymers,
reversed friction pair,
static friction,
PTFE,
POM,
PE-UHMW
Related subjects:
Materials sciences,
Materials sciences, other,
Nanomaterials,
Functional and smart materials,
Materials characterization and properties

© 2023 Mariusz Opalka, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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