Friction Coefficient Tables in Air and Vacuum

Friction coefficient tables for solid lubricants, metals, plastics and anti-friction materials

Friction coefficient tables for various material pairs in atmosphere and vacuum are provided below. The data was collected from various sources [1,2,3]. See the definition of friction coefficient.

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
Steel	Aluminium Bros	0.45
Steel	Brass	0.35
Steel(Mild)	Brass	0.51
Steel	Cast Iron	0.4
Steel	Copper Lead Alloy	0.22
Steel (Hard)	Graphite	0.21
Steel	Graphite	0.1
Steel (Mild)	Lead	0.95
Steel	Phos Bros	0.35
Steel(Hard)	Polythened	0.2
Steel(Hard)	Polystyrene	0.3-0.35
Steel (Mild)	Steel (Mild)	0.74
Steel(Hard)	Steel (Hard)	0.78
Steel	Zinc (Plated on steel)	0.5
Steel	Tungsten Carbide	0.4 – 0.6
Steel	Teflon	0.04
Steel	Polythene	0.2
Steel	Polystyrene	0.3-0.35
Steel	Plexiglas	0.4 – 0.5
Steel	Hard Carbon	0.14
Steel	Graphite	0.1
Steel	Copper-Lead Alloy	0.22
Steel (Mild)	Copper	0.53
Steel (Mild)	Aluminum	0.61

Friction Coefficient of Wood, Leather, and Stone

Material Pair	Static COF	Dynamic COF
Hardwood on hardwood	—	0.129
Oak on oak, parallel to the grain	0.62	0.48
Oak on oak, perpendicular to the grain	0.54	0.32
Cast iron on oak	—	0.49
Brick on wood	0.6	—
Clean wood on metals	0.2–0.6	—
Leather on iron	—	0.25
Leather on oak, parallel to the grain	0.61	0.52
Leather on cast iron	—	0.56
Leather on metal	0.6	—

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

Ceramic	Counterface	μ
Al2O3	Al2O3	0.33–0.50
Al2O3	Al2O3	0.20–0.9
α-Al2O3	α-Al2O3	0.38–0.42
Al2O3	Al2O3–SiC composite	0.53
Al2O3–SiC composite	Al2O3–SiC composite	0.64–0.84
B4C	B4C	0.53
SiC	SiC	0.52
SiC	Si3N4	0.53–0.71
WC	WC	0.34
Si3N4	Si3N4	0.42–0.82

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 ice friction coefficient behavior, as shown in the figure below.

Material	μs (0°C)	μs (-5°C)	μs (-10°C)
Ski lacquer (pigmented nitrocellulose plasticized with phthalate)	0.05	0.11	0.43
Paraffi n wax	0.04	0.27	0.37
Norwegian wax (sulfur-free, bituminous wax)	0.045	0.1	0.2
Swiss wax (highly refi ned, bituminous, hydrocarbon wax with 1.5% Al powder)	0.05	0.1	0.2
Polytetrafluoroethylene (PTFE)	0.04	0.05	0.55

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 Material	Flat Material	μinitial	μsteady-state
Cu	Cu	1.2	0.6
Cu	Glass	1.2	0.65
Fe	Fe	0.7	0.65
Fe	Glass	0.8	0.85
Steel	Steel	0.6	0.55
Steel	Glass	1.3	0.62
CuO	CuO	0.7	0.65
Cu2O	Cu2O	0.65	0.62
Fe2O3	Fe2O3	0.62	0.6
Fe3O4	Fe3O4	0.3	–

Friction coefficient table in fretting regime as a function of humidity

Metal		μ steady-state
	0–2% RH	10–12% RH	49–50% RH
Fe	0.45	0.4	0.25
Ni	0.42	—	0.19
Ti	0.35	0.4	0.28
Cr	0.25	—	0.22