RESIDUAL-STRESS IN CEMENTED CARBIDE FOLLOWING A COATING PROCESS AND AFTER AN ION-IMPLANTATION POSTTREATMENT OF THE COATING

The residual stress in cemented carbide, specifically in the WC phase, following PVD and CVD coating processes is studied together with the effects of ion implantation post-treatment of the CVD-coated material. Over the depth range studied, the compressive stress in the WC is una ffected by the PVD coating process, but is changed to tensile after a CVD TiN coating process. In contrast, a dual alumina/Ti(C,N) CVD coati ng treatment produces a higher compressive stress in the WC. An ion im plantation post-treatment has a beneficial effect on the tensile stres s under CVD TiN by reducing it to near-zero or to a compressive stress where the magnitude of the effect depends on ion implanted, coating t hickness, and acceleration energy. The post-implantation has no effect on the compressive stress in the alumina coating or its Ti(C,N) inter layer. (C) 1998 Elsevier Science S.A. All rights reserved.