Structures and properties of hard and superhard nanocomposite coatings

Various approaches to creating multicomponent nanocomposite coatings of high and superhigh hardness (from similar or equal to 30 to 100-120 GPa) are reviewed with particular emphasis placed on mechanisms underlying the increase in hardness in thin (<= 10 pm) coatings. The deposition technologies considered include magnetron sputtering, ion beam-assisted and vacuum arc depositions. A classification of hard and superhard coatings with high thermal stability is given. Possible applications of such nanostructured coatings are discussed and prospects for the field are outlined.