Mechanical properties of ion-plated TiN films on AISI D2 steel

TiN films were deposited on AISI D2 steel substrates without and with a titanium intermediate layer using a hollow cathode discharge (HCD) ion plating technique. The structure of the him was determined by X-ray diffraction (XRD) and the composition was measured by X-ray photoelectron spectroscopy (XPS). The microhardness and adhesive strength of the as-deposited coatings were measured as well. The results of X-ray diffraction and X-say rocking curves showed that the TiN film exhibited a (111) preferred orientation. The hardness of coatings was found to be related to the N/Ti composition ratio and the porosity in the TiN films. The results of scratch test show that the high critical load is a measure of the adhesion of the TiN film, while the low critical load can be used as a qualitative measure of the toughness of the TiN film. The interfacial diffusion depth increased with the average substrate temperature during the ion plating process. From the results of scratch test and the depth profiles of secondary ion mass spectrometry (SIMS), the adhesive strength of the coating/substrate interface increased with increasing interdiffusion depth. Moreover, the results indicated that the Ti interlayer can enhance the adhesion strength of the coatings. (C) 1998 Elsevier Science S.A. All rights reserved.