Electrochemical micromachining of microgroove arrays on phosphor bronze surface for improving the tribological performance

A high friction coefficient and a low wear rate of contacted surfaces are essential elements to friction pairs between the stator and the rotor in ultrasonic motors. It has been shown that surface textures have a significant effect on improving the tribological performance of friction pairs. In this paper, microgroove arrays are introduced to the stator surface for improving the tribological performance of friction pairs between the stator and the rotor in ultrasonic motors. Microgrooves were fabricated on a phosphor bronze surface by through-mask electrochemical micromachining (TMEMM). Parameters, namely, the electrolyte inlet pressure, applied voltage, pulse duty cycle, and frequency, were varied to investigate their influences on the dimensions and morphology of the microgrooves. Results showed that the width and depth of the microgrooves were strongly affected by the applied voltage and frequency, while the morphology of the microgrooves was dependent on the electrolyte inlet pressure and the pulse duty cycle. Compared with a smooth surface, the friction coefficient increased from 0.245 to 0.334 and less abrasion was obtained when a surface was textured with microgrooves of which the width and depth were 185.6 and 57.6 μm, respectively. Microgroove arrays might play an important role in enhancing the performance of ultrasonic motors.