MULTILAYER COATINGS AND THEIR USE ON MACHINING TOOLS

摘要

Multilayer protective coatings that are applied over a substrate are disclosed that comprise a plurality of superimposed multilayer units. Each multilayer unit contains two or more superimposed thin layers in which at least two layers are compositionally different. The properties of the resulting coating are a combination of the properties of the individual layers. One layer of a multilayer unit may provide hardness or wear resistance and another layer may provide lubricity, for example. The thickness of the individual layers can be related to the microscopic surface relief of the substrate to which the protective coating is applied. One disclosed multilayer unit comprises three layers: an oxidation resistant layer; a nitride layer; and a layer of disordered boron and carbon material.