Electrorheological Properties Of Surfactant Modified Titanium Oxide Particles Prepared By Electrostatic Spraying Method

Electrorheological(ER) fluids is a sort of suspension system which consist of micron and nanon polarizable particles dispersed in dielectric oil. ER fluids have broad application prospects in electrical control components with such features as reversible regulation, rapid response, energy conversion. The property of ER fluids is subject to the morphology and component of dispersible particles. At present, the preparation method of ER particles is liquid-phase method that has some defects of technology resulting in uncontrollable shape and size of particles, low purity, which severely put a brake on the development of ER fluids. To cope with the problem, we first adopted a more suitable method named electrostatic spraying (ES) to prepare ER particles whose chemical composition is titanium oxide (TiOx) modified by polyvinylpyrrolidone (PVP) and stearic acid (SA). Meanwhile, we studied on the process of ES and selected hydrolysis-precipitation (HP) method as the representative of tradition method. By comparing the ER effect of ES-TiOx/PVP/SA particles and HP-TiOx/PVP/SA particles, we proved the ER performance of TiOx/PVP/SA particles prepared by ES method is more excellent.The main research contents and conclusions are as follows:(1) In the experimental process, the main technological parameters of ES method are PVP and Tetra-n-butyl Titanate (TBT) solution content, voltage, receive distance. We used controlling variables method to study the relationship between these parameters and particles' morphology. Through the comparison and analysis, The optimal process parameters is ascertained as:mass fraction of PVP is 0.5%, mass fraction of TBT is 15%, voltage is 20kV and receive distance is 5cm.(2) To contrastively study on ES-TiOx/PVP/SA and ES-TiOx/PVP particles, we used scanning electron microscope (SEM), X-ray (XRD) and infrared spectroscope (FT-IR) to characterize these particles. The results showed that the two kind of particles are amorphous state and regular sphere whose size distribution range is 200-300nm. By testing the contact angle between particles thin film and silicone oil, we found that after modified by SA, TiOx/PVP/SA particles have better wetting property with silicone oil than TiOx/PVP particles. Their ER performance were tested and results showed that TiOx/PVP/SA based ER fluid presents higher yield stress and more stable anti shear stability than TiOx/PVP based ER fluid.(3) TiOx/PVP/SA particles were synthesized by ES method and HP method respectively and characterized by means of SEM, XRD, FT-IR and laser particle size distribution test (LPSD). The results showed that HP-TiOx/PVP/SA particles are regular sphere whose average size is 340nm and the average size of ES-TiOx/PVP/SA particles is 236.7nm. Their ER performance was tested and compared. The results showed that ES-TiOx/PVP/SA based ER fluid presents higher yield stress and more stable anti shear stability than HP-TiOx/PVP/SA based ER fluid.In conclusion, we prepared titanium oxide particles modified by PVP and SA through ES method and improved the ER property of titanium oxide particles. This outcome is conducive to the development of ER fluids.