| 摘要 |
PURPOSE:To obtain silicon nitride powder almost free from impurities and impure anions in a high yield by mixing silicon nitrode powder contg. fine powder with an aqueous inorg. acid soln., removing impurities by a reaction, removing anions, and carrying out drying. CONSTITUTION:Silicon nitrode powder contg. fine powder of <=0.7mum particle size is mixed with an aqueous inorg. acid soln. to prepare a slurry of <=3pH, and the acid soln. in the slurry is reacted with impurities contained in the silicon nitride powder to remove the impurities. The purified silicon nitride powder is settled and separated. A slurry contg. the silicon nitride powder is introduced into a column packed with an anion exchange resin to remove anions contained in the slurry, and the slurry is dried. When the silicon nitride powder used as a starting material does not contain particles of <=0.7mum particle size, the powder settles, yet it is not desirable because the amount of impurities such as metals and silica removed is reduced.
|
