| The method of electrical discharge in water was applicated to the preparation for the high pure superfine alumina with a safer supply of low voltage direct-current power. The results were outlined here with:Al(OH)3 and aluminum powder were obtained by electrical discharge in the de-ionized water from the aluminum particles with different purity. The impurities in the powder are inherited from those in the aluminum particles. There is no pollution in the discharge process.The physical mechanism of the electrical discharge had been studied in the dissertation, from which the aluminum content of the powder is primarily dependent on the amount of the removal at each intermittent discharge which is determined by the energy of the discharge that is the time of the voltage, the current and the discharge time width.The surface topographies of the discharged aluminum particles were studied. The spark was caused by the contact between aluminum particles and the Al(OH)3 layer on the sparkled surfaces that ends the spark. Therefore the discharge should have been continued if the layer were removed. Of cause that is the case of a short circle. As the time of sparkling increased, the spark will get out. So the experiment can be maintained by stirring or after the particles were washed by the diluted hydrochloric acid.The powder as obtained was wet ground in a planetary ball mill. The influence of the parameters from the planetary ball mill on the milling results was studied. The powder with higher content of Al(OH)3 was obtained after four hours ball milling at 250 r/min. The high purityα-Al2O3 powder was got after calcined at 1200℃for 2 hours. The purity was determined by ICP-OES. The results showed that the purity ofα-Al2O3 is 99.9932%, the mean particle size of theα-Al2O3 powder after an ultrasonic treat for 8 minutes is 16.54μm.
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