Effect of Ag content on friction and wear properties of Ag and V co-doped CrN coatings at 25–700 °C

Abstract

Since the lubrication and wear resistance of important sliding parts are related to the safe operation of the whole system, it is urgent to improve the friction and wear performance of sliding parts in a wide temperature range. On this basis, Ag and V co-doped CrN coatings with varied amounts of Ag were deposited onto silicon wafers and Inconel 718 sheets by unbalanced magnetron sputtering technology. The morphology and elemental composition of the coatings were measured by Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. And the mechanical properties were assessed utilizing scratch tester and nanoindentation. The increase of silver content reduces the mechanical properties of the coating. Excessive Ag not only reduces the hardness and elastic modulus of the Ag and V co-doped CrN coating but also reduces the adhesion between the coating and the substrate. Furthermore, the friction and wear properties of the coatings against Al2O3 balls in a wide temperature (25 °C–700 °C) range were tested by a high-temperature tribometer. CrVN/Ag-0.5A coatings show the lowest wear volume at all temperatures and the lowest friction coefficient at high temperatures. Post-wear testing Raman spectroscopy measurement showed the tribo-chemical products formed on the surface of the coating effectively reduce the coefficient of friction.