| 摘要 |
PURPOSE: A method for fabricating silica powder using ultrasonic spray pyrolysis is provided to produce large quantities of spherical solid, low density hollow or porous silica using the precursor solution by ultrasonic spray pyrolysis after preparing a precursor solution using sodium silicate, acid solution, water and urea. CONSTITUTION: The method comprises a step (a) of preparing a silica precursor solution by dispersing and dissolving sodium silicate solution (SiO2/Na2O) and acid solution to be reacted with the sodium silicate solution into a solvent of water; and a step (b) of preparing spherical solid silica powder, low density hollow silica powder or porous silica powder by reacting the precursor solution under the conditions that flux is 5 to 45 L/min, and reaction temperature is 400 to 1,300 deg.C after injecting the precursor solution of the step (a) into an ultrasonic spray pyrolysis unit, wherein the sodium silicate solution contains 25 to 45 wt.% of SiO2 and 10 to 20 wt.% of Na2O, and the acid solution is one or more acids selected from the group consisting of halogenated hydracid including boric acid, sulfuric acid, nitric acid, acetic acid and hydrochloric acid, and oxalic acid, wherein a ratio of water to sodium silicate solution is 2.5 to 6 in the step (a), and the acid solution to be reacted with the sodium silicate solution the solvent of water in an amount of 15 to 24 wt.% of the sodium silicate solution in the step (a), wherein urea is additionally added to the solvent of water in an amount of 0.7 to 1.5 wt.% of the sodium silicate solution in case of the low density hollow silica powder in the step (a), and wherein urea is additionally added to the solvent of water in an amount of 4 to 8 wt.% of the sodium silicate solution in case of the porous silica powder in the step (a).
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