Research On Preparation And High Temperature Performance Of MRF For Transmission

Magnetorheological Fluids(MRF)is an intelligent material consisting of magnetic particles,base fluid and additives.It presents a Newtonian fluid state in the absence of a magnetic field,and can be transformed into a solid-like state in milliseconds in the presence of a magnetic field.Its liquid-like solid state transition is reversible,and can be controlled by current-controlled magnetic field.Therefore,it has been widely used in shock absorption,power transmission and other aspects.The following aspects are studied in this paper:In the aspect of the composition of MRF,through a large number of experiments,a variety of MRF samples are prepared by using a variety of surfactants.The sedimentation stability of MRF samples is observed,and a variety of surfactants which could make MRF have better sedimentation stability are screened out.The properties of magnetic particles such as ferric oxide,iron-nitrogen compound and carbonyl iron powder are compared.The preparation methods,molecular structure and properties of base carriers such as silicone oil,mineral oil and synthetic oil are investigated.Through orthogonal experiments,according to the classification of various surfactants screened out,the compound experiment is carried out in three groups.The influencing factors of settlement stability and viscosity of magnetorheological fluids are found out,and two optimum surfactant formulation methods are determined.The validation experiments are carried out and the final formulation scheme is determined.The experimental method is improved according to the properties of surfactants..The molecular structure and properties of various surfactants are studied,and the properties of different kinds of base fluids and magnetorheological fluids are investigated.The effects of high temperature environment on surfactants are observed,the experiments of viscosity-temperature,volatilization and expansion properties of base carrier fluid are carried out,and the viscosity-temperature characteristics of magnetorheological fluid and settlement stability after high temperature are studied.The components of magnetorheological fluids suitable for use in high temperature environment are found out,and the abrupt phenomena in the viscous-temperature curve of magnetorheological fluids are analyzed.The sedimentation stability and viscosity of magnetorheological fluids prepared with different magnetic particle mass fractions,different particle sizes of a single kind of magnetic particle,mixed use of two particle sizes and addition of nano-magnetic particles are studied.The effects of magnetic particle mass fraction,particle size,shear rate and temperature on the shear yield stress of magnetorheological fluids are investigated.The preparation scheme of magnetorheological fluids with excellent properties is determined.