| 摘要 |
PURPOSE:To obtain a microporous body having low thermal conductivity, excellent in heat insulating property, and minimal in the change with the lapse of time by using a superfine-grained powder prepared by subjecting a superfine- grained powder held at high temp. where the adsorption of water molecule does not occur to coagulation preventing treatment. CONSTITUTION:Raw materials such as SiCl4, are burned at >=1700 deg.C in the presence of O2 and H2 and, if necessary, diluting gas in a reaction furnace 1 and hydrolyzed, and the resulting superfine-grained powder of 1-20nm grains diameter is introduced, while being held at a high temp. (>=150 deg.C) where the adsorption of water molecule does not occur without being cooled down to room temp., into a deoxidation and surface treatment furnace 2 to undergo coagulation preventing treatment with a surface treating agent (e.g. trimethylmethoxysilane). Subsequently, a mixture is prepared by mixing 100-25wt.% of the above coagulation-prevented superfine-grained powder A2 with 0-75wt.% of fine-grained powder (e.g. of pearlite) of 5-10000nm primary grain diameter and this mixture is compacted.
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