| 摘要 |
PURPOSE: A manufacturing method of silica glass by sol-gel process is provided to eliminate impurities of sol, especially metallic impurities and silica agglomerates, effectively. An ultrasonic treatment is much efficient in removing pores of the sol. Accordingly, the obtained silica glass has improved purity required to optical fibers or semiconductors. CONSTITUTION: The method comprises the steps of: (i)mixing silica, dispersant such as tetramethyl ammonium hydroxide and tetraethyl ammonium hydroxide, binder such as polyethyloxazoline and polyvinyl acetate, gelation agent such as methyl formate, methyl lactate and ethyl lactate and deionized water; (ii)eliminating impurities of sol by centrifuging and then pores by 20-50kHz strength of ultrasoniv waves; (iii) molding sol and gelling; (iv)demolding gel, then drying at 30-80°C and 65-80% of relative humidity; (v)thermal-treating as the following steps: heating at 10-50°C/hr to 300-600°C for the elimination of remaining organics of gel, at 100°C/hr to 500-100°Cfor an effective time to separate gel and eliminate remaining OH ions in Cl2 gas atmosphere, at 100°C/hr to 1100-1400°C for about 5hrs. in He gas atmosphere.
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