The main functions of surface materials are to modify and reinforce the surface functions instead of reforming the composition of the bulk material. Some examples of surface modifications by coating processes include Physical Vapor Deposition (PVD), electron beam physical vapor Depositions (EB-PVD) Chemical Vapor Deposition (CVD), plasma and thermal spraying, sol-gel, cladding and electroplating. Surface modification processes can be classified as hardening by flame, induction, laser or electron beam, high energy treatments, e.g. ion implantation and plasma immersion ion implantation and diffusion treatments, e.g. carburizing and nitriding