Effective, Shortened Drying of Agar-Gelcasting Al2O3 Tube Through Immersing in Acetone

A liquid drying agent, i.e. acetone, was employed for allowing the faster drying of Al2O3 tubes fabricated by agar gelcasting than the conventional air drying. The mixture of Al2O3 slurry and agar solution was separately prepared and then mixed prior to molding out of a set of warmed glass tubes. After the mixture transformed into gelled tube, the gelled tube was demolded and then immersed in acetone at different periods of time from 0 to 50 h. The immersed periods of 50 h led to the acetone replacement for water being inside of the gelling tube by 74 wt.% and then shortened the drying period to be 25 min. On the other hand, the conventional air drying spent 420 min drying completely. After drying, the immersed tubes possessed spherical cross section; whereas, no immersed tubes showed the deformation of cross section. The shortened drying was in line with the smaller drying shrinkage (4.7%), broader pore-size distribution and higher porous microstructure, comparing to the conventional air drying. The mechanism of acetone replacement for water was attributed to the acetone-water concentration gradient creating their inter-diffusion.

The Characteristic of Inner Surface Coating on Porous Al2O3 Tube by Electrophoretic Deposition

The nano-porous Al2O3 layer was performed onto inner surface of micro- porous Al2O3 tube by using electrophoretic deposition (EPD). Initially, Polypyrrole (Ppy) was applied on inner wall of tube to make conductive surface. The Al2O3 deposition was carried out in Al2O3 suspension with 5 wt % solid content in ethanol medium system using various applied voltages. Thickness of the deposited layer depends on applied voltages, after sintering at 1400oC the morphology of the deposited layer was investigated by FE-SEM. The good deposited surface without cracks and peeling has been prepared under applied voltage condition of 10 V.

Synthesis of Potassium Ionic Sieve Membrane and its Selectivity to Potassium Ion in Seawater

Potassium ionic sieve membrane was synthesized on porous α-Al2O3 tube support by the hydrothermal synthesis. The zeolite membranes were characterized by means of XRD and SEM. And the single-gas permeability through the membranes and selectivity to K+, Na+, Ca2+, Mg2+ were measured. The results show that the ideal separation factor is 3.68, which is close to Knudsen diffusion ratio 3.74 for H2/N2; the separation factors of the potassium ionic sieve membrane are , , respectively, indicating its high separation selectivity to potassium ion.

Electrical Properties of ZnO Film Prepared by Thermal Oxidation Method

Zn films were deposited on Al2O3 tube with Au electron and Pt wire by direct current magnetron sputtering, then ZnO films were synthesized by thermal oxidation in different temperature using resistance furnace. Surface topography of films was investigated by atomic force microscope. The resistance of ZnO films in air and other atmosphere was tested in a gas sensor test system. Results showed that the films surface morphology changed significantly during thermal oxidation growth. ZnO film synthesized at 1000 0C for 3 minutes has the smallest grain (32.6nm), the biggest roughness (60.9nm). Resistance of ZnO films declined with the increasing of heater power. The resistance of the ZnO layers depends dramatically on the sputtering time (direct proportion to the film thickness). The resistance of ZnO films in 10 minutes sputtering time is one order of magnitude higher than that in 80 minutes.

The Photodecomposition of Acetaldehyde in Gas Phase Using Immobilized TiO2 on Porous α-Al2O3 Tube

AbstractsA study on the photocatalytic degradation of acetaldehyde using immobilized TiO