ENHANCING CORROSION-RESISTANCE OF PVD-COATED TOOLS

It is known that conventional PVD coatings like TiN and CrN offer a li mited corrosion resistance due to their intrinsic porosity, that local ly exposes the substrate. In the manufacturing of cutting, forming and plastic molding tools this fact restricts, in some cases, the option of steels that present a high hardness after heat treatment, but have a low corrosion resistance: for example, cold work tool steels and hig h speed steels. In the present work two ways to overcome this problem were studied: using an electroless NiP interlayer with a PVD CrN topla yer and using a doublelayer of PVD CrN. Both solutions presented a sat isfactory adhesion and improved the corrosion resistance when compared to single PVD CrN coatings. (C) 1998 Elsevier Science S.A. All rights reserved.