Abstract: Method for the production of glassy monoliths via the sol-gel process, whereby the sol is gelled and dried to a Xerogel, which is sintered to a glassy monolith.

Abstract: Sol-gel process for the production of large glass monoliths, whereby tetraalkoxysilane is added to a dispersion of pyrogenically produced silica and the ratio of SiO2:TEOS is 2.6 to 5.5:1.

Abstract: Process for the production of monoliths by means of the sol-gel process, comprising the following steps: a. hydrolysis of an alkoxide in aqueous solution to form a hydrolysate and optionally evaporation to optimum concentration of the same, b. addition of an oxide prepared by the pyrogenic route, c. mixing of the hydrolysate of the alkoxide with the oxide prepared by the pyrogenic route to form a colloidal sol, d. optional removal of coarse contents from the colloidal sol, e. gelling of the colloidal sol in a mould, f. optional replacement of the water contained in the resulting aerogel by an organic solvent, g. drying of the aerogel, h. heat treatment of the dried aerogel, the coarse content being removed from the colloidal sol.

Abstract: Process for the production of monoliths of glass by means of the sol-gel process, comprising the following steps: a) dispersion in water of an oxide prepared by the pyrogenic route, b) hydrolysis of an alkoxide in aqueous solution to form a hydrolysate, c) mixing of the hydrolysate of the alkoxide with the oxide prepared by the pyrogenic route to form a colloidal sol, d) optional removal of coarse contents from the colloidal sol, e) gelling of the colloidal sol in a mould, f) replacement of the water contained in the resulting aerogel by an organic solvent, g) drying of the aerogel, h) heat treatment of the dried aerogel.

Abstract: Sol-gel-process to prepare aerogels comprising the preparation of a solution of a compound having the formula Xm-M-(OR)n?m, the hydrolysis of the compound to give a sol, gelation, drying, densifying and sintering. This method can be used to treat radioactive residues constituted by aqueous solutions of radioactive substances.

Abstract: Particularly shaped articles constituted by silicon oxide, as such or with suitable additives, prepared by room temperature molding according to a process comprising: preparation of a sol starting from a silicon alcoxide, or from a silicon alcoxide and at least a precursor of at least one of the additional elements; hydrolysis of the sol obtained thereby; addition of colloidal silica; pouring the resulting mixture into the desired mould; sol gelling and fast removal of the solid product; gel drying; gel densification by means of a thermal treatment at temperature ranging from 900 ° C to 1500 ° C. The articles can be used as preforms for the optic fiber spinning.