Abstract
The aim of this work was to investigate effects of film thickness on the single layered zirconium oxynitride (Zr(N,O)) films. These films were deposited on AISI 304 stainless steel substrates, at a constant temperature 450℃, by using hollow cathode discharge ion-plating system (HCD-IP) in an argon-oxygen-nitrogen atmosphere. The grain sizes of less than 15 nm show nanocrystalline structure of the films. Regarding to color variations, the intrinsic colorations of Zr(N,O) films were observed, the films are deposited at 0, 2, and 5 sccm O2 flow rate, and the extrinsic colorations of films were observed for deposited condition of 8 sccm O2 flow. Three phases (ZrN, Zr2ON2 and m-ZrO2) in the films could be identified by a modified method developed in this study from XRD and XPS results. The amount of oxide and/or oxynitride phases changed with the different film thickness for the Zr(N,O) films. The structure of Zr(N,O) films became unstable, peak of X-ray diffraction pattern shifting and amorphization, with the different film thickness for the films deposited at 8 sccm O2 flow rate. The increase of hardness with increasing film thickness was observed. The residual stress of Zr(N,O) films was relieved with increasing oxygen flow rate forming oxide in the film, but no specific trends were correlated with the film thickness. The compressive residual stress of stainless steel substrate increased with increasing the thickness of Zr(N,O) film. As compared with film thickness, the packing density of films plays a significant role in corrosion resistance. In potentiodynamic polarization scan, different surface condition of mirror type AISI 304 stainless steel contributed to the different corrosion potential in 5% NaCl solution.