Friction and Wear Properties of PTFE-Based Friction Material Used in Ultrasonic Motor during Running-in Stage

In 200 hours,the operating parameters of ultrasonic motor (USM) were monitored and surface roughness,surface morphology,debris characteristics of stator and rotor were observed and analyzed used laser scanning confocal microscope to discuss friction and wear properties of USM. The result show that after running for 80 h,the performance of USM became stable. In the early stage,adhesive wear was the main wear mechanism and there were many large lump debris on the surface of stator. In stable friction stage,there were many corrosive pitting on worn surface of friction material and a small amount of particulate wear debris can be observed on stator surface. Fatigue wear was one of wear mechanisms. Abrasive wear was always the important wear mechanism in this stage. Apparent ploughs can be seen on the stator surface,the wear mechanism was abrasive wear. Due to the ultrasonic vibration,wear debris was removed from the friction surface in stable wear stage and therefore it is hard to observe wear debris on the interface of stator and rotor. The ultrasonic vibrations had an effect of eliminating the debris from the friction surface.