Preparation of W-TiC alloys from core-shell structure powders synthesized by an improved wet chemical method

In order to improve the homogeneous distribution of the TiC particles and facilitate the TiC particles to distribute in the tungsten grain interiors,two kinds of TiCdoped tungsten precursors with a core-shell structure were prepared by an improved wet chemical method at different reaction temperature conditions.Consequently,fine platelike precursor(200-400 nm)and flower-like precursor(approximately 1.25μm)are obtained.After reduction and sintering,the microstructures of the samples were characterized by scanning electron microscopy and transmission electron microscopy.In the sample sintered from the platelike precursor,TiC particles with sizes in the range of40-300 nm and an average size of approximately 80 nm were uniformly distributed in the tungsten matrix with a high share in the grain interiors.However,in the sample sintered from the flower-like precursor,the TiC particles with sizes in the range of 50-700 nm are significantly aggregated and non-uniformly distributed in the tungsten matrix.As a result,the sample sintered from the plate-like precursor achieves higher mechanical properties and a much narrower range of bending strength values than that sintered from the flower-like precursor.The average bending strength of the sample sintered from the plate-like precursor is 655 MPa,which is higher than that of the sample sintered from the flower-like precursor(524 MPa).Different reaction mechanisms and dispersing stabilities of the TiC particles at different temperature conditions should be accounted for the differences between the two samples.

Tuning the face orientation of ZnO nano/microcrystals by a wet chemical method

We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods, nanoflakes, nanoplates, and microrods by a simple wet chemical method. Growth duration is found to play a crucial role in the morphologies of these ZnO nano/microcrystallites. In addition, growth conditions are systematically studied as a function of precursor concentration and temperature. The structural and optical characteristics of the ZnO samples are further investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence spectroscopy.

Preparation and photocatalytic activities of 3D flower-like CuO nanostructures

Hierarchical 3D flower-like CuO nanostructures on the Cu substrates were synthesized by a wet chem- ical method and subsequent heat treatment. The synthesis, structure and morphologies of obtained samples under different concentrations of NazS203 were investigated in detail and the possible growth mechanisms of the 3D flower-like CuO nanostructures were discussed. Na2S203 plays a key role in the generation of the 3D flower-like CuO nanostructures. When the concentration of Na2S203 is more than 0.4 mol/L, the 3D flower-like CuO nano- structures can be prepared on the Cu foils. The photocatalytic performances were studied by analyzing the degra- dation of methyl orange （MO） in aqueous solution in the presence of hydroxide water （H202）. The 3D flower-like CuO nanostructures exhibit higher photocatalytic activity （96.2% degradation rate） than commercial CuO particles （36.3% degradation rate）. The origin of the higher photocatalytic activity of the 3D flower-like CuO nanostructures was also discussed.