Recent advances in the depth-resolved X-ray analysis of residual stresses and stress-free lattice parameters in Ti(C-N)-gradient coatings

摘要

Thin hard coatings are widely employed in order to improve the efficiency of cutting and forging processes through an increased wear and corrosion resistance of the respective tools. Therefore, the coatings are more and more refined. In recent investigations, PVD-gradient coatings of Ti(C-N) on cutting edges of cemented carbide have shown a significantly higher wear resistance than conventional TiC- or TiN coatings. However, the residual stress states in the coatings strongly influence the in-service properties of the coatings and of the entire components. In order to understand the influences of the residual stress states, X-ray residual stress analyses were performed. A special approach was developed which allows the non-destructive depth-resolved determination of the residual stress states and stress-free lattice parameters of the coatings. As a consequence ofthe Ti(C-N)-gradient, the residual stresses and stress-free lattice parameters varied linearely over the thicknessof the coatings.