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 ~ 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.