Characteristics of Cr2N/Cu multilayered thin films with different bilayer thickness

Nanostructured Cr2N/Cu multilayer coatings were deposited periodically by a bipolar asymmetric reactive pulsed DC magnetron sputtering system. The crystalline structure of multilayer coatings was determined by a glancing angle X-ray diffractometer. Microstructures of thin films were examined by an atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. A nanoindenter, a micro Vickers hardness tester and pin-on-disk wear tests were used to evaluate the hardness, fracture toughness and tribological properties of the thin films, respectively. Electrochemical tests in 3.5 wt.% NaCl aqueous solution were performed to evaluate the corrosion resistance of multilayered coatings. The bilayer period of the nanostructured multilayer coatings were controlled within the range from 5 to 40 nm. It was found that the hardness increased with decreasing bilayer period and leveled off at small periods around 6–12 nm. The Cr2N/Cu multilayered coatings with bilayer periods of 5 and 6 nm exhibited a combination of high hardness, good tribological and good anticorrosion performance in this study.