Yan-Li Shang

Preparation and Electrorheological Property of NaNO3-Doped Y2O3 Material

Abstract A new class of electrorheological (ER) material using rare earth (RE = Y) oxide as the substrate, NaNO3doped Y2O3 materials, were synthesized using Na2CO3 and Y(NO3)3 as starting materials. Their ER performance, dielectric property, and crystal structure were studied. The results show that doping NaNO3 can markedly enhance the ER activity of the Y2O3 material. For the suspensions of these materials in dimethyl silicone oil, a clear dependence of the shear stress on the doping degree of NaNO3 was observed, and the optimal value of Na/Y molar ratio of 0.6 in doping degree was discovered, the relative viscosity ηr(ηE/ηO, E = 4.2 kV·mm−1) of the suspensions is nine times higher than that of pure Y2O3 material. The new results of the relationship between ER effect and the microstructure were obtained, which are helpful for further understanding the mechanism of ER effect and synthesizing a good ER material.

Preparation and Electrorheological Property of Y4O(OH)9(NO3)-NH4NO3 Materials

Abstract The new electrorheological (ER) material, a particle material composed of Y 4 O(OH) 9 (NO 3 ) and NH 4 NO 3 , was obtained. They display better ER performance. The shear stress of the suspension of Y 4 O(OH) 9 (NO 3 ) (NH 4 NO 3 ) 2.8 material in dimethyl silicone oil reaches 1469 Pa at an electric field strength ( E ) of 4.2 kV. mm −1 and the shear rate (γ) of 150s −1 . The relative shear stress, τ E /τ 0 (τ E and τ 0 are the shear stresses at E = 4.2 and O kV-mm −1 , respectively), is up to 29, which is 19 times that of pure Y 2 O 3 material. The dielectric and conductive property of the materials play important roles in the modification of the ER effect of the particle materials. The researches on these new ER materials are very useful for obtaining a better understanding on the mechanism of the ER effect and finding an ideal ER material.

MICROSTRUCTURE AND ELECTRORHEOLOGICAL PROPERTY OF PURE TiO2 PARTICLE MATERIAL

JUAN WANG AND SHAO-HUA ZHANG School of Vehicle and Transmission Engineering, Beijing Institute of Technology, Beijing, 100081, China Pure titanium dioxide (Ti02) particle materials were prepared by hydrolyzing titanium tetrachloride (TiC14). The microstructures of these materials were determined by X-ray difiactometer (XRD) and accelerated surface area & porosimetry apparatus (BET) etc. The Ti02 materials obtained by calcinations under different temperatures revealed distinctly different microstructures in terms of crystal structure type, surface area, pore size, pore volume and grain size. The relationship between the microstructure of the Ti02 materials and their electrorheolagical (ER) activity was investigated.