Characterization and Electrorheological Effect of H_2SO_4-modified TiO_2 Particles

H2SO4-modified TiO2 particles were prepared using a sol-gel method followed by impregnating the dry gels with sulphuric acid and were used to fabricate an electrorheological(ER) fluid with high ER activity.The as-synthesized H2SO4-modified TiO2 particles were characterized by fourier transform infrared(FT-IR),X-ray diffraction(XRD),BET N2 adsorption-desorption isotherm analysis,and the ER effect and dielectric spectra of the ER fluids were measured.The results show that H2SO4-modified TiO2 particles have smaller size of crystal grains and higher specific surface area due to the restraint of SO2-4 from the grain growth.Under the same measured condition and electric field strength of 3kV/mm,the ratio of field-induced shear stress to zero field shear stress(τE/τ0) of TiO2 particles is 80,while that of H2SO4-modified TiO2 particles is more than 500.The observed ER performances are reasonably explained by the stronger interfacial polarization,which is brought by the specific structures of the H2SO4-modified TiO2 particles.