Papers by Author: Xue Bing Hu

Abstract: The Ta₂O₅-based ceramics were prepared by dry pressing/sintering technique using Ta₂O₅ and Al₂O₃ as the starting materials. The present work investigated the effect of alumina (Al₂O₃) additions on the composition, microstructure, thermal expansion coefficient (TEC) and bending strength of Ta₂O₅ ceramics. The thermal expansion of the samples was measured by the dilatometry method. It was found that Al₂O₃ additions can effectively inhibit the β to α phase transformation in Ta₂O₅ ceramics. Orthorhombic AlTaO₄ as the minor phase formed when 2.5 and 7.0 wt% Al₂O₃ was added. The addition of Al₂O₃ results in obvious change of TEC and an increase of bending strength. This work demonstrated that the addition of Al₂O₃ is an effective way to modify the TEC and mechanical strength of Ta₂O₅ ceramics.

Abstract: Membrane surface modification is the important method to decrease membrane fouling. The hydrophilic modification of ceramic membrane with nano-sized inorganic coating is prepared by the wet chemical methods. The thin nano coating is not a separating top layer but distributes uniformly on the surface of the membrane pore wall. The coating does not change the structure of the membrane pores. Therefore, water flows on not the pore wall but the nano coating surface. The results show that the water flux of the modified membrane is higher than that of the unmodified membrane despite that the mean pore size of the modified membrane decreases. The “boundary slip” is used to explain this special phenomenon. What generates the slippage The slippage is relative with the molecular layer adhered tightly on the hydrophilic pore wall, the roughness and the surface charge of the nano coating, the interaction between the ions in water and the nano coating, et al.

Abstract: Micro-tubular solid oxide fuel cell (SOFC) has been fabricated with NiO-YSZ hollow fiber as anode support and La_0.6Sr_0.4Co_0.8Cu_0.2O_3−δ-Sm_0.2Ce_0.8O_1.9 (LSCCu-SDC) composite cathode. The NiO-YSZ hollow fiber anode was prepared by the immersion-induced phase inversion technique and shows a special asymmetrical structure with porous sponge-like structure in the middle and finger-like structure on the inner and outer side of the hollow fiber. A thin and dense electrolyte membrane (about 12μm) was deposited on the anode by a vacuum-assisted dip-coating process. The performance of the as-prepared hollow fiber SOFC (HF-SOFC) was tested at 600-800°C with humidified H₂ as fuel and ambient air as the oxidant. The peak power densities of 531.1, 362.5 and 214.6mWcm^-2 can be obtained at 800, 700 and 600°C, respectively. The good performance at intermediate temperature (IT) indicates promising applications as power sources for portable devices for the prepared YSZ-based micro-tubular SOFCs with LSCCu-SDC composite cathode.

Abstract: Using aluminum chloride, aluminite powders and butyl titanate as raw materials, alumina- aluminum titanate fiber was prepared by sol-gel method at 1200°C. The influences of the holding time on the aspect ratio, the bulk density, the thermal conductivity coefficient and the heating linear shrinkage of the fiber were studied systemically. The results show that the holding time has an important effect on the properties of the fiber. With the increase of the holding time from 0 h to 3 h, the aspect ratio of the fiber decreases from 870 to 210 and the bulk density of the fiber adds from 352 Kg•m-3 to 432 Kg•m-3. Furthermore, the thermal conductivity coefficient of the fiber keeps rising from 0.162 W•m-1•K-1 to 0.199 W•m-1•K-1 and the heating linear shrinkage of the fiber decreases from 2% to 1.82%.

Abstract: The mullite sol was prepared using tetraethyoxysilane (TEOS) as raw materials. Aluminum titanate (AT) powders were coated with the sol by dipping. The influence of the concentration of the mullite sol and pH value on the microstructure of the coated AT powders was studied. The results showed that AT powders are coated homogeneously and the thickness of the mullite film is about 0.15 μm when the concentration of the mullite sol is 0.18 mol·L-1 and pH value is 3.0.