Preparation of nanometer silicon carbide powders by sol-gel processing

Abstract

Nanometer silicon carbide powders are synthesized by sol-gel and carbothermal reduction processing with TEOS( tetraethoxysilane, (C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> ) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> ) ) and saccharose (C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> ) as starting materials. Silica sol is prepared by hydrolyzed TEOS with deionized water, ethanol (CH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> CH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> OH) as cosolvent and hydrochloric acid as catalyst. It further dehydrated to make colorless and transparent gel and dried to obtain drying gel at 40°C. Carbothermal reduction of the prepared silica/ saccharose composites is carried out in argon atmosphere of 500 Pa in a high vacuum furnace at temperatures ranging from 1200°C to 1500°C to form powders. The surface morphology and crystal structure of nanometer SiC powders have been investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and Raman spectrum. Experimental results show that the samples have better crystalline state and its typical diameters reach nanometer magnitude.