アルミナ/チタン酸ジルコン酸鉛による環状振動子を用いた進行波型超音波モータを開発したWu (OB) の論文が Smart Materials and Structures に掲載されました。
J. Wu, Y. Mizuno, and K. Nakamura, “A traveling-wave ultrasonic motor utilizing a ring-shaped alumina/PZT vibrator,” Smart Mater. Struct., vol. 28, no. 12, 125017 (2019).
Considering that high Young’s moduli and low ultrasonic attenuation of fine ceramics may enhance driving force and reduce energy dissipation, in this study, we exploit the usage of fine ceramics as vibrating bodies of ultrasonic motors (USMs). Several alumina vibrating bodies were fabricated and bonded to annular lead-zirconate-titanate (PZT) disks to form ring-shaped vibrators, where traveling waves with the 3rd bending modes were excited to frictionally drive the rotor. First, we explored the fundamental vibration properties. As predicted, the alumina/PZT vibrators provided relatively high force factors, high electromechanical coupling factors, and low damping compared to the stainless-steel/PZT one with similar structure. Subsequently, through experimental assessment on load characteristics, we found that the rotation speed of the alumina/PZT motor at 20 V was larger than that of the stainless-steel/PZT motor at 250 V, and meanwhile, it exhibited superior maximal-torque-to-voltage and maximal-output-power-to-voltage ratios; these results imply that satisfactory performance is achievable with our motor. Besides, alumina’s chemical resistance and electrical resistance make our motor potentially applicable to the acid/alkaline atmosphere and the intensively alternating-current magnetic field.