Research On Active Driving Technology Of Trace Lubricating Liquid Drops Based On Surface Acoustic Wave Devices

The continuous development of my country's space industry has put forward new requirements for the long-term and stable operation of satellites.The momentum wheel is a key component of satellite condition control.Once it fails,it directly affects the satellite's service status.An important reason for the failure of the momentum wheel is the failure of the lubrication of the internal bearing components.A part of the lubricating oil required for the working of the momentum wheel bearing comes from the oil reservoir,and moves to the bearing along the inner wall of the bearing cavity through diffusion.Due to the volatilization and creep losses in the diffusion process,the bearing contact surface often cannot obtain enough lubricating oil.Therefore,this paper studies the driving technology of droplets based on the piezoelectric effect,and works in the aspects of providing driving power and reducing motion resistance,so that the droplets can move quickly.The surface acoustic wave piezoelectric droplet driver and bulk vibration piezoelectric droplet driver are designed,and the advantages and disadvantages of each driver and the applicable working conditions are analyzed.The parameters such as the material and thickness of the piezoelectric layer of the SAW piezoelectric droplet driver and the material and size of the interdigital electrode are designed.The drawings required for etching the interdigital electrode are drawn.The parameters such as the material and thickness of the piezoelectric layer of the bulk vibration piezoelectric droplet driver are designed,and the type of the interdigitated electrode is determined.Control schemes for the wettability of the driver surface are designed.Through frequency domain simulation,the resonance frequencies of the surface acoustic wave piezoelectric droplet driver were determined.The vibration modes of the surface acoustic wave piezoelectric droplet driver at various resonance frequencies are analyzed.The surface deformation of the ring-shaped interdigital electrode SAW piezoelectric droplet driver at resonance frequency is analyzed.The different morphologies of droplets on lyophilic and lyophobic surfaces are simulated.The vibration caused by the surface acoustic wave is simplified as a sine wave surface vibration,and the internal state of the droplet under the action of the surface vibration is qualitatively analyzed.The optimal sputtering gas pressure value for preparing the piezoelectric layer was studied,and the performance parameters of the piezoelectric layer film prepared under the gas pressure value were examined.The thin film is plated on the finished interdigitated electrode,and a bulk vibration piezoelectric droplet driver is prepared.The surface acoustic wave piezoelectric droplet driver was prepared by preparing a piezoelectric layer film and processing interdigital electrodes.Both drivers have a stable resonance frequency.The chemical modification method and the method of depositing the silica particle coating first and then chemically modifying the surface were used to adjust the wettability of the zinc oxide thin film specimen,thereby reducing the affinity of the droplet to the surface.Experiment need to connect the signal generator,power amplifier and piezoelectric droplet driver.Through experiments,it was verified that the parallel interdigital electrode surface acoustic wave piezoelectric droplet driver can drive the droplet to slide and can drive the droplet evaporation;it was verified that the annular interdigital electrode surface acoustic wave piezoelectric droplet driver can make the droplet appear tip and can drive the droplet to slide;it has been verified that the bulk vibration piezoelectric droplet driver can drive the droplet to eject and can drive the droplet evaporation.