Thin films in tribology

This article examines tribology. More emphasis is on the effect of wear on engineering materials as it is an important and costly aspect of engineering industries. Wear degradation is one of the most failure mode incurring millions of funds by maintenance and replacement in modern industries. Apart from lubricants, thin film deposition technologies are well established for the improvement of wear resistance in high friction operations. There have been a widespread of hard coatings such as diamond and diamond-like carbon coatings for tribological applications in the last decades. However, the limitation of such coatings is that plastic deformation of such hard coatings begins from the substrate material. This is because the wear mechanisms of the material will depend on the mechanical properties such as hardness and ductility of the substrate and the coating. In depth knowledge of the macro-mechanical mechanisms dominating the tribological process are discussed. Different wear mechanisms are briefly reviewed with respect to their effect on substrate-film system and hardness. The influence of the thin film deposition method employed and the surface treatment used on the tribological properties of the coated materials are discussed.