Improving the properties of titanium nitride by incorporation of silicon

Thin films of Ti-Si-N have been deposited by physical Vapor deposition (PVD) with the intention to improve the wear resistance of TiN coatings. The coatings are prepared by reactive unbalanced magnetron sputtering using two separate Ti and Si targets and a rotating substrate holder. The silicon concentration in the deposited films varies between 0 and 15 at.%. SEM observations and X-ray diffraction analysis (XRD) show that the addition of Si to TiN coatings transforms the [111] oriented columnar structure into a dense finely grained structure. From TEM investigations and XRD analyses, the crystallite sizes of TiN are observed to be below 20 nm. XPS analysis shows the presence of silicon nitride, while electron and X-ray diffraction results do not suggest the presence of crystalline Si3N4. This result clearly indicates that these films have a composite structure consisting of TiN nanocrystallites embedded in amorphous silicon nitride. The hardness of the nc-TiN/a-SiNx coatings reaches 3500 HV0.1. The abrasion resistance measured by ball cratering can be enhanced by a factor of 6 in comparison with TiN deposited under the same conditions. (C) 1998 Elsevier Science S.A. All rights reserved.