Research And Preparation Of Magnetorheological Materials With High Stability

Magnetorheological fluid (MRF) as one of the most intelligent and promisingmaterials attracts wide attention of scholars and research institutions all over theworld。More and more industries competed each other in the past decade and foreigncountries have formed excellent MRF and magnetorheological fluid device available.Under the influence of an external magnetic field with a high shearing stress;excellent temperature stability; lower zero-field viscosity; power and good chemicalstability; quick response. These excellent properties will make it a more broadapplication. This paper is mainly from the following two aspects ofmagnetorheological fluid to explore and study.The first part picks the method of polymer coated to modify magnetic particles,select mechanical and excellent mechanical properties of such a polymer-polyethersulfone to dissolve in an organic solvent, carbonyl iron disperses in theabove-mentioned solution, in the continuously stirring state and in spray drying，tosynthesis the surface-modified carbonyl iron particles. Using the preparation ofmagnetic particles get the modified magnetorheological fluid. By SEM, infraredtesting, density testing and other means，these methods confirm the particles are whatwe want. Further characterization by sedimentation test and shear yield stress testresults prove the prepared composite magnetic particles have a goodanti-sedimentation stability and yield strength.The second part is using now commonly used chemical coprecipitation synthesisto compound high performance nano-Fe3O4magnetic particles which are coated byoleic acid, and then prepare the magnetorheological fluid. By XRD, particle sizedistribution testing,density testing and other methods show that most of thesynthesized nano Fe3O4magnetic nanoparticles are with excellent crystallinity and itssize distribution is about10nm with superparamagnetic and lipophilic. They study themechanism of action of this approach through the purchase of nanometer Fe3O4magnetic particles，and in this way large and small particles are mixed approach. Theresults prove that: small particles have a good complement to the large and increase the yield strength of MR fluid and improve the overall dispersion stability.