Influence of Al Contents on the Microstructure, Mechanical, and Wear properties of Magnetron Sputtered CrAlN Coatings

CrAlN (0 < x < 0.1) coatings were deposited on SA304 substrate by a reactive magnetron sputtering. The microstructure and composition of the as-deposited coatings were systematically characterized by field emission scanning electron microscopy/EDS and atomic force microscopy, and the phase formation by x-ray diffraction (XRD). The hardness of the coatings was investigated using nanoindentation, while wear properties were investigated using pin-on-disk tribometer. XRD study reveals that the deposited CrAlN coatings crystallized in the cubic B1 NaCl structure. The minimum and maximum hardness of the coatings are found to be 15.28 and 18.81 GPa, respectively. The COF and wear rate are found to be 0.48 and 2.25 × 10^?5 mm³/N · m, which is lower than the CrN coatings deposited and characterized under the same environment (0.63 and 2.25 × 10^?5 mm³/Nm).