Surface textured polyimide composites for improving conversion efficiency of ultrasonic motor.

Two ways to enhance conversion efficiency of the ultrasonic motor (USM) were developed. According to mechanical and tribological properties, an advanced polyimide (PI) friction material was fabricated. In comparison to conventional polytetraflfluoroethylene (PTFE) friction material, the novel PI friction material enhanced efficiency from 29% to 44%, an improvement of 51.7%. The results indicated high friction coefficient and high elastic modulus were essential for improving efficiency. Inspired by the unique topography, the micro-dimples were introduced into PI friction material which improved the efficiency from 44% to 53%, an increment of 20.5%. The optimum parameter was diameter of 200 μm and area density of 7%. The effect of surface texture on tribological behavior and output characteristic of the USM was comprehensively explored. • The advanced PI friction material and the surface texture enhance efficiency from 29% to 53%, an increase of 82.8%. • High friction coefficient and high elastic modulus are the main reason for improving the conversion efficiency of the USM. • The surface texture enhance the efficiency of the USM because of increased tangential frictional force. [ABSTRACT FROM AUTHOR]