Relation between Friction and Wear Properties and Delamination Behavior of Amorphous SiC Film Coated by Helicon Sputtering

Abstract

SiC films were deposited on titanium substrate specimens by using a helicon-sputtering apparatus. Wear tests were carried out on the specimens using a pin-on-disk type testing machine, and the delamination behavior of the films during the tests was discussed from a viewpoint of fracture mechanics. Amorphous SiC film is formed by the sputtering, while crystalline SiC film is formed when the substrate is heated. The wear resistance of titanium is greatly enhanced by the amorphous SiC film with lower frictional coefficient and higher interfacial fracture toughness than the crystalline SiC film. The wear depth of the amorphous SiC at delamination is much deeper than that of the crystalline SiC film. In the wear test, parallel cracks are initiated perpendicular to the frictional direction before partial delamination of the film occurs, and the delamination area extends all over the wear scar with a small increase in rotation cycles. The delamination of film starts when the interfacial strain-energy release rate, G12, reaches the interfacial fracture toughness, GC12, which is decreased by the accumulation of fatigue damage during the wear cycles.