**4. Wear**

Tribology is the branch of science dealing with contacting surfaces in relative motion. It deals with friction, lubrication and wear of interacting surfaces. Wear is recognised as the phenomenon of undesirable removal of materials from the surface due to interaction with the counter surface. Wear resistance is not the basic property of any material, but depends on environment. It varies even if it is not exposed to the same work environment. Almost all moving parts of machines durability, reliability and life depend upon one main parameter: wear. Therefore, wear property demands its analysis as strong need for advanced and reliable material property for application oriented environment. Wear can be controlled by the selection of right material and proper operating conditions [21]. Wear is a critical factor composing of dynamic parameters, environmental parameters, and material parameters. So wear resistance property is usually analysed for purpose of lubrication, to screen material & its surface treatments, sometime to establish relationship between finishing methods (processing) and its performance. The different type of wear is sliding wear, impact wear and rolling contact wear. Sliding wear is a relative movement between two solid surfaces acting tangential to each other.
