Friction and wear properties of CrAlN and CrVN films deposited by cathodic arc ion plating method

Chromium nitride (CrN) films are superior to the titanium nitride film in corrosion and wear resistances, and friction behavior. CrN has been widely applied to the molding dies, machine parts and sliding part. In the present paper, additions of aluminum and vanadium into CrN films were performed with an expectation of improvement in tribological properties. CrN, CrAlN and CrVN were deposited by a cathodic arc ion plating. Deposited films were characterized by X-ray diffraction for crystal structure identification and energy-dispersive X-ray spectroscopy for chemical composition analysis. Diffraction peaks that appeared were similar in position and orientation in all films because the crystal structure and the lattice constant for CrN, VN and AlN are close to each other. The composition of the film deposited with Al and V was estimated to be Cr70Al30N and Cr50V50N, respectively. Knoop hardness test showed that CrAlN was harder than CrN and CrVN. Friction and wear tests were carried out by a ball-on-disk tribometer with stainless steel and cemented carbide balls as a counter material, with and without lubricant. Flaking occurred on CrN with stainless steel ball in wear tests without lubrication by ball-on-disk tribometer, but that did not occur on CrAlN and CrVN films. In the case of the wear test with cemented carbide ball, depth of wear track on CrN film reached to the substrate. The friction coefficient was almost the same for CrN and CrAlN films; however, that for CrVN film was lower than other films, in motor oil. V addition into CrN film successfully improved its tribological properties.