硫酸改性TiO2粒子的表征与电流变性能研究

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（τ_E/τ₀）仅为80, 而硫酸改性TiO₂电流变液的τ_E/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.

Characterization and Electrorheological Effect of H2SO4-modified TiO_2 Particles

H2SO4-modified TiO_2 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 H_2SO_4-modified TiO_2 particles were characterized by fourier transform infrared (FT-IR), X-ray diffraction (XRD), BET N_2 adsorption-desorption isotherm analysis, and the ER effect and dielectric spectra of the ER fluids were measured. The results show that H_2SO_4-modified TiO_2 particles have smaller size of crystal grains and higher specific surface area due to the restraint of SO_4~(2-) 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 (τ_E/τ_0) of TiO_2 particles is 80, while that of H_2SO_4-modified TiO_2 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 H_2SO_4-modified TiO_2 particles.