H. Decho, A. Mehner, J. Kohlscheen, H.-W. Zoch
February 7, 2018
Titanium aluminum nitride (TiAlN) coatings are frequently used for cutting applications because of their high wear resistance and high thermal stability. Doping with additional elements and a multilayered film structure can significantly improve the wear resistance of these hard coatings. For this context, the wear resistant of TiAlN based multilayer film systems was investigated. Films with different contents of chromium, zirconium and silicon were deposited by reactive DC magnetron sputtering on cemented tungsten carbide (WC/Co) milling inserts. Doping content and layer thickness were varied by the target power. Chemical composition, microstructure, adhesion, hardness and tool life time was analyzed by glow discharge optical emission spectroscopy (GDOES), electron microscopy, scratch tests, hardness indentation tests and milling tests. An industrial TiAlN coating was used as reference for the cutting test. Milling inserts coated with TiAlN/Cr X N and TiAlN/ZrN films showed no improved life time in comparison to the TiAlN reference, whereas the lifetime of the TiAlN/Si X N Y coated milling inserts was enhanced significantly for silicon contents up to 1.8 at.-%. A further increase of the silicon content the resulted in a significant decrease of adhesion and cutting performance.