Multilayer coated hard alloy cutting tool

摘要

The present invention concerns a tungsten carbide base cutting tools formed on sintered hard alloy substrate material. Multiple hard coatings are deposited on the Co-enriched surface layers of the substrate material, and a maximum value of the Co concentration in a layer occurs within a distance of 50 mu m of the external surface of the substrate material, and this surface layer region is referred to as the denuded zone because the surface region is substantially free of carbides, carbonitrides and nitrides of Ti, Ta, and Nb containing W. The multilayer coating consists of a primary coating of TiCN, a secondary coating of Al2O3 and the surface coating consisting of at least one of TiCN and TiN. The interface between the substrate material and the primary coating is provided with a first intermediate coating consisting of TiN. The interface between the primary coating and the secondary coating is provided with a second intermediate coating consisting of at least one layer of TiC, TiCO and TiCNO.