| 摘要 |
PURPOSE:To form compression stress and to temper quartz glass incapable of tempering in the past by immersing the plate of a porous silica material such as dry gel and sintered gel into a soln. contg. a metallic compd. and providing a diffusion layer on the surface thereof. CONSTITUTION:The plate of dry gel and sintered gel obtained by a sol-gel method wherein at least metallic alkoxide and pulverized silica are used as a raw material is immersed into a soln. contg. a metallic compd. (i.e. ethanol soln. of ethylsilicate and a boric acid aq. soln. or the like) and a diffusion layer is formed on the surface of dry gel on sintered gel. Then tempered glass is produced by sintering it after drying it. By this method, quartz glass and borosilicate glass incapable of tempering in the past can be tempered. Therefore these can be applied i.e. to a cover glass for a timepiece and to various cover glasses wherein these were weak in strength in the past and could not be used.
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