The development of cubic-carbide-free surface layers in cemented carbides without nitrogen

Abstract

In cemented carbides, the surface-region composition can be modified to provide added toughness for coated cutting-tool substrates by developing a cobalt-enriched, cubic-carbide-free surface layer. Typically, such modifications have been prepared by establishing nitrogen gradients in the cemented carbide through the additions of cubic nitrides or nitrification of the cubic carbides during sintering. Recently, methods have been developed for forming cubic-carbide-free surface layers in compositions without the intentional addition of nitrogen. In this study, the kinetics of formation of such layers are compared for compositions with and without nitrogen. The effects of sintering atmosphere and cubic-carbide composition are also discussed.