MULTILAYER, MULTICOMPONENT, AND MULTIPHASE PHYSICAL VAPOR-DEPOSITION COATINGS FOR ENHANCED PERFORMANCE

Hard physical vapor deposition (PVD) coatings are widely used today for enhanced performance, and PVD hard coatings have evolved because they can be deposited at temperatures much lower than those commonly needed for the chemical vapor deposition of coatings. Although binary coatings such as TiN are still very popular and are tried in many different applications, new multilayer, multicomponent, or multiphase coatings are finding successful applications. Multicomponent coatings such as TiAlN(x) or Ti(C,N) are better than TiN in certain tooling applications, and Ti0.5Al0.5N makes an excellent diffusion barrier in microelectronic devices. Reactively deposited coatings such as MoN(x), CrN(x), and NbN(x) all form multiple phases, and either individual phases or mixed phases of these materials are now being tested for tribological applications. Many nitride coatings such as beta-Mo2N can extend the rolling contact fatigue life of rolling elements such as bearings by a factor of 5 or more. Multilayer polycrystalline TiN/NbN superlattice films have shown hardness as high as 5200 kgf mm-2, and other new superlattice films such as TiN/Ni are being developed. Although many of these new coatings will be tried on tools, the future for them lies beyond tooling. The ability to deposit these new coatings at low substrate temperatures without damaging die properties of the substrate, which can be done with plasma assisted PVD processes, will open up many new tribological and microelectronic applications.