Improving output performance of ultrasonic motor by coating MoS2 on the stator

To improve the wear resistance of frictional interface of ultrasonic motors (USM), a new tribological pair was designed. The phosphor bronze stator surface of USM urgently needs modification to match with aluminum alloy rotor surface that was treated by micro-arc oxidation (MAO). The tribological properties of stator coating, MoS2 and WS2, were compared at the material level. The strengthening mechanism of stator coating was interpreted by extracting microscopic information from molecular dynamics (MD) results. The results showed that new tribological pair significantly enhance the output performance and energy conversion efficiency, particularly the MoS2 coating. When the preload was 280 N, input voltage was 500 V, and frequency was 36.2 kHz, the maximum efficiency of MoS2 reached to 46.12%.