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Static friction of normal and reversed metal–polymer sliding pairs

Mariusz Opalka
Mariusz Opalka
   | 03 mar 2023
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Data publikacji: 03 mar 2023
Zakres stron: 152 - 159
Otrzymano: 04 lis 2022
Przyjęty: 09 sty 2023
DOI: https://doi.org/10.2478/msp-2022-0040
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© 2022 Mariusz Opalka, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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 material Unit pressure p [MPa]
0.5 1.0 2.0
PE-UHMW 0.10 ± 0.002 0.09 ± 0.001 0.08 ± 0.001
POM 0.09 ± 0.001 0.08 ± 0.001 0.07 ± 0.001
PTFE 0.05 ± 0.001 0.06 ± 0.001 0.05 ± 0.001

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

Unit pressure p [MPa]
0.5 1 2 Average
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 material Unit pressure p [MPa]
0.5 1.0 2.0
PE-UHMW 0.12 ± 0.001 0.11 ± 0.001 0.11 ± 0.001
POM 0.16 ± 0.002 0.14 ± 0.002 0.12 ± 0.002
PTFE 0.09 ± 0.002 0.08 ± 0.001 0.06 ± 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-UHMW 0.93 730 −100 135 80
POM 1.41 2400 −240 to 180 167 150
PTFE 2.6 750 −97 327 -
eISSN:
2083-134X
Język:
Angielski
Częstotliwość wydawania:
4 razy w roku
Dziedziny czasopisma:
Materials Sciences, other, Nanomaterials, Functional and Smart Materials, Materials Characterization and Properties
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