INFLUENCE OF STRESS-DISTRIBUTION ON ADHESION STRENGTH OF SPUTTERED HARD COATINGS

Today's research activities in improving the properties of curling too ls are concentrated on optimizing manufacturing technologies and tool geometry, on alloying of special cutting materials and on coating of t ools. As a result of the poor machinability of new cutting tool materi als, the surface properties are influenced by the grinding process use d during tool manufacturing. In spite of optimized coating parameters, deposited PVD-coatings fail because of insufficient surface propertie s of the substrates. In this contribution, influences of residual stre ss distribution in subsurface layers on interface strength of PVD-coat ed cemented carbides were investigated. Considered topics are the infl uence of grinding, micro blasting, and water peening of carbides on su rface topography and surface integrity. Dependencies between stress di stribution in subsurface layers and interface strength of (Ti,(Al)N-co atings as well as effects on wear behavior in dry machining are highli ghted. Surface properties of the tools are characterized by SEM and X- ray residual stress measurements (XRD). The Xray measurement of the de pth profile of the residual stress distribution is done by using diffe rent lattice planes which correspond to different penetration depths. Due to increased interface strength of micro blasted tools a superior wear behavior in dry machining is observed. (C) 1998 Elsevier Science S.A. All rights reserved.