Study On Anti Oxidation And Stable Aqueous Magnetorheological Fluid Prepared By Sol-gel Method

Magnetorheological fluid(MRF)is a kind of smart material,whose morphology and properties can change rapid and reversible by controllable magnetic field.Aqueous MRF has been widely applied in engineering fields such as magnetorheological finishing efc.for its low viscosity,high yield stress and environmental friendliness,and has very broad application prospects.But because the magnetic particles in MRF is far denser than the aqueous carrier liquid,the magnetic particles will sink down under gravity,which can lead to a decrease of the sedimentation stability of the aqueous MRF.In addition,the magnetic particles in the aqueous MRF are usually the carbonyl iron powders,which are prone to electrochemical corrosion in water for its electrode potential is lower than oxygen,and this problem will reduce magnetorheological effect(MR effect)of MRF and seriously restrict its application.Therefore,improving the sedimentation stability and the oxidation resistance of the aqueous MRF has become the key determinant of weather it can be applied in the magnetorheological finishing efc.In this thesis,a hydrophilic surface modifier(N-Polyether ethylenediamine triacetate,PED3A)was firstly synthesized,then the PED3 A zirconium sol synthesized by sol-gel method was coated on the surface of carbonyl iron powder,at last composite magnetic particles and MRFs were prepared.The structures of the intermediates and final products were characterized by FTIR.The results show that the intermediates and final products had the main characteristic peaks of the expected products;the intermediates(PEG-Cl and PEGED)and the final product(PED3A)was successfully synthesized.The structure and properties of composite magnetic particles were characterized By SEM,FT-IR,XRD,VSM,contact angle and TG-DTA;the anti-oxidization and anti-acidification experiments were designed to investigate the inoxidizability and acidoresistance of composite magnetic particles.The results show that the composite magnetic particles had core-shell structure,PED3 A zirconium sol was uniformly coated on the surface of carbonyl iron particles,and composite magnetic particles had good hydrophilicity,oxidation resistance,acid resistance and soft magnetic properties.The sedimentation stability,oxidation resistance and MR effect of MRFs were also studied.The results show that the sedimentation stability and oxidation resistance of MRFs prepared by composite magnetic particles was effectively improved,and the viscosity,yield stress,repeatability and MR effect of MRFs were satisfactory.