Preparation of Sub-Micron Bi Alloy Powers with the Ultrasonic Mixed Crushing

The powders of the BiInSn alloy were produced by the ultrasonic atomization and the ultrasonic mixed crushing using the different dispersants. In this study, the composition, microstructure, melting point, and size of these powders were observed. The viscosity of different solutions of the dispersants and the mechanical properties of the sintered bulk materials were also tested. From the data analysis and results, we found that the composition of the powders using the different methods was consistent with the as-cast state. In addition, the size of powder produced by ultrasonic mixed crushing was significantly smaller than that ultrasonic atomization. And during the ultrasonic crushing process, with the increase of the viscosity of the dispersant, the size of the final powder also decreased, and even submicron powder were produced. The product of submicron powder could effectively improve the density and mechanical properties of sintered materials. And the principles of ultrasonic atomization and ultrasonic mixed crushing were discussed. We found that the mechanism of ultrasonic mixed crushing to produce powder was the micro-shock-wave theory of ultrasonic cavitation. At the same time, these dispersants were effective in keeping the droplets separate from each other and preventing them from merging back into the larger droplets. The droplet was solidified into a powder by rapid cooling in the end.

Process Optimization of Lycium ruthenicum Murr. Powder Preparation by Airflow Ultrafine Pulverization at Low Temperature and Characterization of its Antioxidant Activity

The processing of ultrafine pulverization Lycium ruthenicum Murr. by airflow is studied to determine the best parameters. Based on the single factor experiment, orthogonal experimental design is utilized to optimization of process parameters. The results show that the water content is 0.5%, air supply pressure is 0.70 Mpa，graded speed is 55 Hz, freezing time in the liquid nitrogen is 2 h. Under the condition of repeated trials, the average grading of L. ruthenicum fruit submicron powder is 19.8167 and#177; 0.53 μm. The contents of the total polysaccharides, anthocyanin and antioxidant activity in the water extract of submicron powders are obviously higher than the normal powder’s, which can efficiently increase the dissolution rate of active ingredients in L. ruthenicum Murr.

Comparison of Physicochemical Characteristics of Submicron Powder and Common Powder of Chrysanthemum morifolium Chuju

The physicochemical characteristics of Chrysanthemum morifolium Chuju powders were investigated to increase its utilization value and to develop novel products. Comparing the physicochemical properties between the submicron powder and common powder, the indicators of repose angle, slip angle, solubility, soakage, dispersibility, the images of SEM, and dissolution of main active components were obtained to evaluate the quality of powder products. The repose angle of submicron powder was 36.76º, while that of the common powder was 48.77º, which represents the appreciable flowability of submicron powder. The wetting time of submicron powder was 103s, which was way less than that of common powder (8963s). The SEM micrographs showed that submicron powder had long cracks on its plant cell. The HPLC chromatograms indicated that the dissolution of submicron powder was higher than that of common powder. The results showed that not only physical but also chemical characteristics of submicron powders were much superior than those of common powders.

SYNTHESIS OF ULTRAFINE NICKEL-IRON POWDER BY THE MAGNESIUM REDUCTION IN GAS PHASE

Ultra fine metallic powders have an increasing application in magnetic materials, catalysts and chemical and metallic industries. In this research, magnesium-thermic reduction in gas phase was used to synthesize an ultra-fine nickel-iron intermetallic compound. Synthesis of nickel-iron submicron powder by metal chlorides and magnesium vapors was studied. Evaporation rate of the chlorides and magnesium in the range of 800 to 920 degrees Celsius was measured in order to control the composition of the resulting compound. The simultaneous reduction of the chlorides was done in a tubular furnace under argon atmosphere at 920 degrees Celsius. Chemical analysis of the resulting compound and the X ray diffraction analysis identified the formation of Ni 3 Fe compound. The particle size of the compound was measured 60 to 230 nano-meters by scanning electron microscopy. In addition, the particles were spherical and homogeneous. The product may be used for production of magnetic and catalytic applications.