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

Microscopic damage caused by fretting wear is of significant concern i n many engineering applications. We report the design and performance of a versatile fretting wear testing machine that uses an electromagne tic actuator under closed-loop control to provide a constant slip ampl itude over a wide frequency range. The machine is equipped with a mech anism that allows for gradual sample contact and precise relocation of the stylus. An innovative method for monitoring frictional forces dur ing the course of a test is incorporated. The machine has been success fully applied to materials treated by three types of plasma surface mo dification: nitrogen ion implantation, thin film alloy deposition and diamond-like carbon film deposition.