Papers by Author: Yang Xian Li

Abstract: Mineral attapulgite powders were heat treated at different temperature from 100°C to 800°C. The effect of heat treatment on properties of attapulgite were studied by particle size distribution, surface free energy, and water vapor adsorption performance. The results show that the medium particle size and surface free energy of attapulgite increase and hygroscopic capacity promptly reduce with the increase of heat temperature .The medium particle size of the raw palygorskite is 3.09 μm, and it becomes 14.12 μm after heat treatment at 800 °C. The surface free energy, polarity component and dispersion component of the natural attapulgite are 45.16mN•m-1, 13.92mN•m-1, 31.24mN•m-1, respectively, and they become 116.22 mN•m-1，116.22 mN•m-1，0.0 mN•m-1 after heat treatment at 800°C. Moreover, the hygroscopic capacity of attapulgite in 24h decreases from 17.1 % to 5.6% after heat treatment at 800°C.

Abstract: The zirconia nanotube arrays on zirconium substrates were formed in (NH4)2SO4 electrolytes containing different concentrations of NH4F (0.5-2.0 wt%). Highly self-organized zirconia nanotubes can be formed with a diameter ranging from 15 nm to 144 nm and a length of 32 μm. The morphology of the nanotubes was strongly influenced by the applied voltages and electrolyte concentrations. Electrochemical testing and scanning electron microscope observation indicated the nanotubes were formed due to the competition of zirconia formation and dissolution under the assistance of electric field.

Abstract: The martensitic transformation in Co50Ni20Ga30 ribbon has been characterized in detail by means of X-ray diffraction and magnetic measurements. The sample showed a structural transition from the body-centered cubic with indexed lattice parameters of a=5.743 Å to martensite with a tetragonal structure with lattice parameters of a=b=5.422 Å and c=6.401 Å. (c/a>1). By comparing the results of the diffraction intensity and the magnetic susceptibility measurements, we found that the proceeding of the martensitic transformation can be divided into several different steps during cooling from 283 K to 213 K. During heating from 673 K to 833 K, the peak width became very wide and the intensity became very low. It reveals an order-disorder transformation.