摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing SiF4 , that prevents pyrolysis residue from being agglomerated into blocks, by using an alkali metal salt or alkaline-earth metal salt of hexafluorosilicic acid, and SiO2 and/or Al2 O3 . SOLUTION: This method uses an alkali metal salt (e.g. Na2 SiF6 ) or alkaline- earth metal salt (BaSiF6 ) of hexafluorosilicic acid, and SiO2 and/or Al2 O3 , to produce SiF4 . These salts may be commercial ones produced at low cost. It is preferable that SiO2 and Al2 O3 are, in general, 99wt.% pure or so. The SiO2 and Al2 O3 have an average particle size of 0.1 to 100μm as that of the primary particles. Quantity of SiO2 and/or Al2 O3 to be used is preferably 1 to 20wt.% based on that of the hexafluorosilicic acid. The preferable pyrolysis temperature is generally 500 to 800 deg.C, although varying to some extent depending on type of the silicate used.
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