Microstructure, mechanical and tribological properties of Cr–C–N coatings deposited by pulsed closed field unbalanced magnetron sputtering

Abstract

Nanocrystalline Cr–C–N coatings were deposited by pulsed closed field unbalanced magnetron sputtering. The microstructure, chemical composition and elemental chemical state of the coatings were investigated using field-emission scanning electron microscopy, glancing incident angle x-ray diffraction and x-ray photoelectron spectroscopy. Mechanical and tribological properties of the coatings were measured by nanoindentation and ball-on-disk wear tests. The Cr–C–N coatings consist of nanocrystalline Cr 7C 3, CrN embedded in an amorphous carbon and CN matrix. The coatings with a N content of 25.5 at.% possessed a highest hardness of 25.4 GPa and a highest H/E ratio of 0.096. Dependent on the C content, the steady state dry coefficient of friction values for Cr–C–N coatings sliding against a WC-Co ball were found in the range of 0.38–0.56. The wear rates of the coatings are in the low range of 1.28–3.44 × 10 − 6 mm 3 N − 1 m − 1 .