Microstructure, mechanical and electrochemical properties evaluation of pulsed DC reactive magnetron sputtered nanostructured Cr-Zr-N and Cr-Zr-Si-N thin films

Cr-Zr-Si-N thin films with various Zr contents were deposited by a bipolar asymmetric pulsed DC reactive magnetron sputtering system. In addition, a Cr-Zr-N film without Si addition was fabricated as a reference. The influence of Zr on the constitution, microstructure, mechanical, tribological and electrochemical properties of Cr-Zr-Si-N films was investigated. The microstructure of thin films was determined by a glancing angle X-ray diffractometer (GA-XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. A nanoindenter, a Vickers micro hardness tester and pin-on-disk wear tests were adopted to evaluate the hardness, toughness and tribological properties of thin films, respectively. The electrochemical properties of thin films were also evaluated in 3.5 wt.% NaCl aqueous solution. In case of the Cr-Zr-Si-N films, the Si content was fixed around 6-8 at.% and various Zr contents ranging from 0.5 to 13.6 at.% were achieved by changing the Zr target power density. In comparison to the Cr-Zr-N reference film, the addition of similar to 7.0 at% Si in Cr-Zr-Si-N films resulted in a refined columnar structure and enhanced mechanical and anti-corrosion properties. A lattice constant expansion of these films was observed with increasing Zr content. A nanostructured thin film with around 5-10 nm grain size was obtained in case of a Cr-13.6 at.% Zr-6.8 at.% Si-N film. In general, the hardness, plastic deformation resistance and corrosion resistance increased also with increasing Zr content in the Cr-Zr-Si-N films. The Cr-Zr-Si-N film containing 13.6 at.% Zr exhibited a combination of high hardness, good mechanical properties, adequate tribological performance and excellent corrosion resistance in this study. (C) 2010 Elsevier B.V. All rights reserved.