摘要 |
PURPOSE:To produce a porous glass having a thickness of several cm and containing pores having diameter of several tens Angstrom , by mixing a sol produced by the complete hydrolysis of a metal alkoxide with a sol produced by the partial hydrolysis, adding fine silica powder to the mixture and gelling, drying and calcining the mixture. CONSTITUTION:A metal alkoxide such as silicon ethoxide is added with a prescribed amount of hydrochloric acid to effect the complete hydrolysis and the obtained solution is converted to a sol 1. Separately, silicon ethoxide is added with a small amount of hydrochloric acid to effect partial hydrolysis and the obtained solution is converted to a sol 2. The sol 1 is mixed to the sol 2 and stirred. Fine silica powder is added and dispersed in the mixture and the pH of the mixture is controlled e.g. by the addi tion of ammonia water. the obtained sol solution is charged in a vessel, closed and left standing to obtain a gel. The vessel is bored with holes accounting for several % - ten odd % of the surface area of the vessel and the content is dried e.g. for 10 days to obtain a dry gel. The dry gel is put into an electric furnace and calcined e.g. at 600-800 deg.C. A porous glass having a thickness of as thick as several cm and containing pores with several tens Angstrom in diameter can be produced in remarkably improved yield by this process. |