硫酸改性TiO_2粒子的表征与电流变性能研究

Characterization and Electrorheological Effect of H_2SO_4-modified TiO_2 Particles

采用硫酸溶液浸渍TiO2干凝胶的方法制备了硫酸改性的TiO2粒子,并组成了具有显著电流变性能的电流变材料.用FT-IR、XRD、比表面积分析仪等表征了样品结构,并测试了其电流变性能.结果表明:由于硫酸根对晶粒生长的阻碍作用,与纯TiO2粒子相比,硫酸改性的TiO2粒子的晶粒尺寸降低,比表面积提高,并含有大量的强极性键SO.当电场强度为3kV/mm时,纯TiO2粒子电流变液的场致剪切应力与零场剪切应力之比(τE/τ0)仅为80,而硫酸改性TiO2电流变液的τE/τ0高达500.产生这些现象可归因于硫酸改性TiO2粒子带来的结构改变赋予其明显的界面极化能力.

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.