Fretting fatigue behaviors and surface integrity of Ag-TiN soft solid lubricating films on titanium alloy

Abstract

Abstract Titanium alloys are widely used in industrial fields because of their superior characteristics, but they also have disadvantages leading to fretting fatigue (FF) damage. The silver-based composite films were deposited on a Ti6Al4V alloy substrate using ion-assisted magnetron sputtering for improving the fretting fatigue (FF) resistance of a Ti6Al4V alloy. The surface morphology was characterized by atomic force microscopy (AFM), and micro-structure was characterized by X-ray photoelectron spectroscopy measurements (XPS), X-ray diffractometry (XRD), and transmission electron microscopy (TEM), respectively. The bonding strength and toughness of films were analyzed using a repeated press–press test system that was manufactured in-house. The FF resistance of titanium alloy with the silver-based composite films was investigated using home-made FF devices. The results showed that the FF resistance of the titanium alloy was improved by the Ag-TiN composite films, which were fabricated with an Ag solid lubricating film doped with a hard TiN phase (60–80 at.% Ag). This is attributed to the fact that the composite films had better comprehensive strength-toughness behavior, friction lubrication property, and high bonding strength. However, when the atomic fraction of Ag in the composite film was larger than 90%, it became difficult to form the TiN phase, and it failed to improve the comprehensive strength-toughness behavior of the composite film.