The Coefficient of Friction

Materials and Material
Combinations
Coefficient of Friction
Clean Lubricated
Steel 0.74 0.16
Copper-lead alloy 0.22 -
Phosphor-bronze 0.35 -
Aluminum-bronze 0.45 -
Brass 0.35 0.19
Cast iron 0.4 0.21
Bronze - 0.16
Sintered bronze - 0.13
Hard carbon 0.14 0.11-0.14
Graphite 0.1 0.1
Tungsten carbide 0.4-0.6 0.1-0.2
Plexiglas 0.4-0.5 0.4-0.5
Polystyrene 0.3-0.35 0.3-0.35
Polythene 0.2 0.2
Teflon 0.04 0.04
Aluminum-aluminum 1.35 0.3
Cadmium-cadmium 0.5 0.05
Chromium-chromium 0.41 0.34
Copper-copper 1 0.08
Iron-iron 1 0.15-0.20
Magnesium-magnesium 0.6 0.08
Nickel-nickel 0.7 0.28
Platinum-platinum 1.2 0.25
Silver-silver 1.4 0.55
Zinc-zinc 0.6 0.04
Glass-glass 0.9-1.0 0.1-0.6
Glass-metal 0.5-0.7 0.2-0.3
Diamond-diamond 0.1 0.05-0.1
Diamond-metal 0.1-0.15 0.1
Sapphire-sapphire 0.2 0.2
Hard carbon on carbon 0.16 0.12-0.14
Graphite-graphite (in vacuum) 0.5-0.8 -
Graphite-graphite 0.1 0.1
Tungsten carbide-tungsten carbide 0.2-0.25 0.12
Plexiglas-plexiglas 0.8 0.8
Polystyrene-polystyrene 0.5 0.5
Teflon-Teflon 0.04 0.04
Nylon-nylon 0.15-0.25 -
Solids on rubber 1-4 -
Wood on wood (clean) 0.25-0.5 -
Wood on wood (wet) 0.2 -
Wood on metals (clean) 0.2-0.6 -
Wood on metals (wet) 0.2 -
Brick on wood 0.6 -
Leather on wood 0.3-0.4 -
Leather on metal (clean) 0.6 -
Leather on metal (wet) 0.4 -
Leather on metal (greasy) 0.2 -
Brake material on cast iron 0.4 -
Brake material on cast iron (wet) 0.2 -