Deposition, characterization and machining performance of multilayer PVD coatings on cemented carbide cutting tools

CrN/TiN and TiN/AlTiN multilayer coatings with different periods were deposited on cemented carbide cutting tools in an industrial-size cathodic arc evaporation device. Nanolayer coatings were particularly studied and the influence of the superlattice period on mechanical behaviors have been investigated. Mechanical properties were first correlated to the period of multilayer and nanolayer coatings. Machining performance of coated cutting tools were then evaluated by turning Inconel 718 superalloy. The decrease of layer periodicity leads to higher microhardness for both compositions. Adhesion tests and surface topography analyses indicate better adhesion and lower roughness for CrN/TiN than for TiN/AlTiN coatings. All these coatings, especially TiN/AlTiN nanolayers, favorably influence flank wear and cutting time for machining Inconel 718 in relatively severe cutting conditions. The relationship between physical properties, coatings compositions and wear mechanisms during machining Inconel 718 is discussed.