Interface Engineering in a Combined Cathodic Arc / Unbalanced Magnetron System

The aim of this project is to show how functionality (in particular adhesion and corrosion resistance) of a coated system depends on the interface between coating and substrate. Interfaces formed by metal ion etching (to clean the substrate surface) and subsequent coating deposition are under investigation. Cross sectional transmission electron microscopy (TEM) and in plane TEM imaging are used to determine the microstructure of the modified substrate surface and of the coating. The elemental distribution of etching material in or on the substrate surface are studied in collaboration with the Fredrick -Seitz Materials Research Laboratory at the University of Illinois.

The dedicated FEG-STEM allows EDX analysis on the cross section with a lateral resolution better than +/- 3 nm. The first figure demonstrates that the interface structure depends on the etching species and ion energy and the second figure shows how these parameters affect coating adhesion. A correlation between practical adhesion and tool performance in end of life test of milling cutters in dry high speed machining was found. Thus the ion etching procedure prior to coating deposition influences the functionality of the coated tool.