Application Of Alumina-titania Composite Coating On Linear Ultrasonic Motor

This research activity is funded by Aviation Science Foundation Programs (51275242).The principle of an ultrasonic motor is that the high frequencies oscillating movement of twopiezoelectric elements were transferred to driving foot, and then, friction drive system to transfer themovement. Nowadays, aviation and aerospace industry, precise positioning industry and other fields paymore attention to linear ultrasonic motor, the higher performance requirements are proposed. Due to thevast different hardness between alumina ceramic rotor and metal stator, the abrasion of stator is terriblewhen ultrasonic motor is running. Friction material is one of the most important factors, which has greatinfluence upon the performance of linear ultrasonic motors.In this project, composite coatings were prepared by atmospheric plasma spraying. The tribologicalproperties and wear mechanism of the coatings were emphasized. The worn surface morphologies of thecoatings were analyzed by scanning electron microscope (SEM), and X-ray diffraction was used toanalyze the phase transition. Adhesion strength and micro-hardness were tested by universal tensile testmachine and microhardness tester, respectively. Based on the research of Al2O3/TiO2, the effect ofoperating parameter and different TiO2content on the performance of coatings were studied. The resultindicated when the current was600A and the voltage was60V, coatings had minimal porosity andmaximum adhesive strength. The content of TiO2affected the powder degree of melting, which causedvast different performance. Al2O3-16wt%.TiO2coating exhibited the best wear resistance and the longestservice life in ultrasonic motors. Then, the different contents of La2O3were doped in feedpowder.Experimental results showed that coating doped with5wt.%La2O3exhibited great performance. Thewear resistance of the coating with4%Sm2O3and1wt.%La2O3was better than that of other coatings.To improve the coating performance further, composite coatings were heated to500℃and kept6hours.The coatings showed the most performance after heat-treatment. Finally, based on above researches,themost optimal coating was deposited on stator. Keep ultrasonic motor running200hours to test theperformance of motor. The results showed that service life and stability of ultrasonic motor wereimproved.