A MACHINE FOR FRETTING WEAR TESTING OF PLASMA SURFACE-MODIFIED MATERIALS

Microscopic damage caused by fretting wear is of significant concern in many engineering applications. We report the design and performance of a versatile fretting wear testing machine that uses an electromagnetic actuator under closed-loop control to provide a constant slip amplitude over a wide frequency range. The machine is equipped with a mechanism that allows for gradual sample contact and precise relocation of the stylus. An innovative method for monitoring frictional forces during the course of a test is incorporated. The machine has been successfully applied to materials treated by three types of plasma surface modification: nitrogen ion implantation, thin film alloy deposition and diamond-like carbon film deposition.