Friction Coefficient Tables in Air and Vacuum

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Tribology Wikipedia > Friction Coefficient Tables in Air and Vacuum

Friction coefficient table of solid lubricants, metals, plastics and anti-friction materials

Friction coefficient table for various material pairs in atmosphere and vacuum (see the definition of friction coefficient) is shown below. The data was collected from various sources [1,2,3].

Material Combination Friction coefficient in air Friction coefficient in vacuum
Fe-Fe 0.3 1.9
Fe-Mg 1 0.6
Fe-Cd 1.5 0.4
Fe-Pb 0.9 0.4
Stainless Steel -Stainless Steel 0.5 2.9
Stainless Steel – Cu 0.3
Stainless Steel-Al 0.4 0.3
Stainless Steel-Mo 0.8
Stainless Steel-Ni 0.8
Stainless Steel-Teflon 0.2
Stainless Steel-Si 0.2
Stainless Steel-Ge 0.2
Stainless Steel-Glass 0.5
Chromium Steel – Chromium Steel 0.5 0.5
Cu-Cu 0.5-1.0 4.8-21.0
Cu-Ni 0.6 1.5-2.0
Al-Al 0.8 1.6-2.2
Al-Ni 2.4
Al-Cu 1.5
Al-Ag 2.2
Brass-Brass 0.4 0.7
Ni-Ni 4.9
Ag-Ag 3.9
Cr-Cr 0.6 3
Au-Au 0.6 4.5
Zn-Zn 1 3
Zr-Zr 1.5
Chromium Steel – MoS2 (vacuum deposition) 0.06
Chromium Steel – MoS2 (friction deposition) 0.06
Cu-MoS2 0.2 0.07
Brass-Steel 0.35
Tire – Asphalt 0.72
Tire – Grass 0.35
Diamond – Diamond 0.1
Glass – Glass 0.9-1.0
Graphite – Steel 0.1
Graphite – Graphite 0.1 0.5-0.8
Ice – Ice 0.02-0.09
Ice – Steel 0.03
Wood – Wood >0.2
Polytetrafluoroethylene – Polytetrafluoroethylene 0.04

Steel friction coefficient table

Materials Static friction coefficient
SteelAluminium Bros0.45
SteelBrass0.35
Steel(Mild)Brass0.51
SteelCast Iron0.4
SteelCopper Lead Alloy0.22
Steel (Hard)Graphite0.21
SteelGraphite0.1
Steel (Mild)Lead0.95
SteelPhos Bros0.35
Steel(Hard)Polythened0.2
Steel(Hard)Polystyrene0.3-0.35
Steel (Mild)Steel (Mild)0.74
Steel(Hard)Steel (Hard)0.78
SteelZinc (Plated on steel)0.5
SteelTungsten Carbide0.4 - 0.6
SteelTeflon0.04
SteelPolythene0.2
SteelPolystyrene0.3-0.35
SteelPlexiglas0.4 - 0.5
SteelHard Carbon0.14
SteelGraphite0.1
SteelCopper-Lead Alloy0.22
Steel (Mild)Copper0.53
Steel (Mild)Aluminum0.61

Friction Coefficient of Wood, Leather, and Stone

Material PairStatic COFDynamic COF
Hardwood on hardwood0.129
Oak on oak, parallel to the grain0.620.48
Oak on oak, perpendicular to the grain0.540.32
Cast iron on oak0.49
Brick on wood0.6
Clean wood on metals0.2–0.6
Leather on iron0.25
Leather on oak, parallel to the grain0.610.52
Leather on cast iron0.56
Leather on metal0.6
Sandstone on sandstone0.364
Granite on granite0.303

Sliding Friction Coefficient Table for Selected Ceramic Materials (Room Temperature in Air)

CeramicCounterfaceμ
Al2O3Al2O30.33–0.50
Al2O3Al2O30.20–0.9
α-Al2O3α-Al2O30.38–0.42
Al2O3Al2O3–SiC composite0.53
Al2O3–SiC compositeAl2O3–SiC composite0.64–0.84
B4CB4C0.53
SiCSiC0.52
SiCSi3N40.53–0.71
WCWC0.34
Si3N4Si3N40.42–0.82

Ice friction coefficient

Depending on pressure, temperature, and the conditions of formation, ice can take on any of at least eight allotropic forms, the largest number for any known substance. These changes impact the friction coefficient behavior, as shown in the figure below.

ice friction coefficient
Friction coeffi cient for stainless steel and ice on polycrystalline ice as a function
of temperature, [3].
Materialμs (0°C)μs (-5°C) μs (-10°C)
Ski lacquer (pigmented nitrocellulose plasticized with phthalate)0.050.110.43
Paraffi n wax0.040.270.37
Norwegian wax (sulfur-free, bituminous wax)0.0450.10.2
Swiss wax (highly refi ned, bituminous, hydrocarbon wax with 1.5% Al powder)0.050.10.2
Polytetrafl uoroethylene (PTFE)0.040.050.55

Friction coefficient table for materials in fretting regime

In fretting, friction coefficients are different for the same pairs of materials due to changes in friction mechanisms. These tables include some data for commonly used materials.

Ball MaterialFlat Materialμinitialμsteady-state
CuCu1.20.6
CuGlass1.20.65
FeFe0.70.65
FeGlass0.80.85
SteelSteel0.60.55
SteelGlass1.30.62
CuOCuO0.70.65
Cu2OCu2O0.650.62
Fe2O3Fe2O30.620.6
Fe3O4Fe3O40.3No

Friction coefficient table in fretting regime as a function of humidity

Metal μsteady-state     
0–2% RH10–12% RH49–50% RH
Fe0.450.40.25
Ni0.420.19
Ti0.350.40.28
Cr0.250.22

[1]. Mechanics and Physics of Precise Vacuum Mechanisms, E.A. Deulin, V.P. Mikhailov, Yu.V. Panfilov, R.A. Nevshupa.

[2]. http://www.engineeringtoolbox.com/friction-coefficients-d_778.html.

[3]. Friction Science and Technology: From Concepts to Applications, Peter J. Blau, 2005

 

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