Tribological properties of surfaces

The real area of contact between two solid surfaces is only a small portion of the apparent area. Deformation of these areas can result in solid state contact through surface films. For clean solid-to-solid contact strong adhesive bonding occurs across the interface. Under these conditions many properties of the solid such as the metallurgical and chemical nature of metals can influence adhesion, friction and wear behavior. The presence of gases, liquids and solid films on the surface of solids markedly alters the tribological characteristics. These surface films can also considerably change the mechanical effects of solid state contact on bulk material behavior.