Abstract: The invention relates to aqueous silica dispersion with a pH in the range from 8 to 14, comprising a base chosen from the group consisting of alkali metal hydroxides, (akyl)ammonium hydroxides or a mixture thereof, at least 35% by weight of silica particles surface-treated with an amino-organosilane (I) and/or a product of hydrolysis of compound of formula (I), 3% to 35% by weight of at least one polyol, 20% to 60% by weight of water, preparation of such dispersion and the use thereof in fire-resistant glass.

Abstract: Sol gel process for producing hydrophobic transparent films for polymeric substrates, the process relates to the sol-gel reaction of silicon alkoxide carried out in certain conditions. The sols obtained were, without limiting, spin- or dip-coated onto polymeric substrates then thermally cured into transparent-abrasion resistant coating. Such coating transmit visible light, but absorb wavelengths of ultraviolet light which cause degradation of the substrate surface and resultant adhesion-loss of the protective coating upon weathering.

Abstract: An optical article, having an almost complete isotropy and dimensions equal to or lower than 500 .mu.m, is prepared by a sol-gel procedure comprising a preliminary step wherein the mould is filled cold with a sol containing the desired oxide precursors, sol gelation, gel drying, removal of the gel from the mould and the subsequent miniaturization of the dried gel. The optical article can be used for optic telecommunications.

Abstract: Process for the preparation and the deposition of vitreous films on substrates comprising: the dissolution of one or more metal alkoxides in aprotic solvent, the hydrolysis of the resulting solution, the eventual removal of the formed alcohol, the deposition of the resulting sol on the substrate surface of interest and the final drying of the film.

Abstract: Sol gel process for producing hydrophobic transparent films for polymeric substrates, the process relates to the sol-gel reaction of silicon alkoxide carried out in certain conditions. The sols obtained were, without limiting, spin- or dip-coated onto polymeric substrates then thermally cured into transparent-abrasion resistant coating. Such coating transmit visible light, but absorb wavelengths of ultraviolet light which cause degradation of the substrate surface and resultant adhesion-loss of the protective coating upon weathering.

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: An optical article, having an almost complete isotropy and dimensions equal to or lower than 500 .mu.m, is prepared by a sol-gel procedure comprising a preliminary step wherein the mould is filled cold with a sol containing the desired oxide precursors, sol gelation, gel drying, removal of the gel from the mould and the subsequent miniaturization of the dried gel. The optical article can be used for optic telecommunications.

Abstract: An optical article, having an almost complete isotropy and dimensions equal to or lower than 500 ?m, is prepared in which the sol-gel procedure comprises a preliminar step wherein the mould is cool filled with a sol containing the interesting oxide precursors, the sol gelation, the gel drying, the removal of gel from the mould and the final miniaturization of the dried gel. The optical article can be used for optic telecommunications.

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: A method for the preparation of aerogels that involves the exchange of the liquid present in the aquagel with xenon and the subsequent extraction thereof.

Abstract: The present invention relates to glassy inorganic films, characterized by a high chemical stability and a high adhesion, containing, among the others, titanium dioxide, employable to coat metal surfaces characterized by the presence of oxides, particularly stainless steel sheets. The coated structures obtained thereby, which are the second object of the present invention, are used to build many articles such as pipes, reactors, exchangers, containers, and so on. With reference to the peculiar case of stainless steel structures coated by the above film, these ones can be used in the food industry since that film coated article shows specific and very high photobactericide properties.

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: An optical article, having an almost complete isotropy and dimensions equal to or lower than 500 ?m, is prepared by a sol-gel procedure comprising a preliminary step wherein the mould is filled cold with a sol containing the desired oxide precursors, sol gelation, gel drying, removal of the gel from the mould and the subsequent miniaturization of the dried gel. The optical article can be used for optic telecommunications.

Abstract: It is described a process based on sol-gel chemistry suitable to the production of nanocomposite materials being photoluminescent at ambient temperature, comprising silicon grains of dimension of nanometers embedded in a silica matrix.

Abstract: The present invention relates to a Si2O glass characterized by a high homogeneity, prepared through a sol-gel procedure.

Abstract: Sol-gel process for the production of optical fiber preforms or overcladdings by preparing a sol, gelling the sol, drying the wet gel to a dry porous gel and densifying the dry gel to fully dense glass, wherein during the calcination treatment from 350° C. to 900° C. to remove organic impurities in the dry gel, it is carried out at least one reduced-pressure phase at a pressure comprised between about 0.01 and 0.5 bar.

Abstract: A method for the preparation of aerogels that involves the exchange of the liquid present in the aquagel with xenon and the subsequent extraction thereof.

Abstract: Process for the preparation and the deposition of vitreous films on substrates comprising: the dissolution of one or more metal alkoxides in aprotic solvent, the hydrolysis of the resulting solution, yhe eventual removal of the formed alcohol, the deposition of the resulting sol on the substrate surface of interest and the final drying of the film.

Abstract: A sol-gel process is described that allows dry gels to be produced, and where necessary, the corresponding dense vitreous bodies, around an incompressible insert. A particular feature of the process is the step of rotating a container holding the sol and incompressible insert throughout the gelling step under such conditions that a wet gel adhering to the insert is produced, which is then dried. The process is useful particularly for the production of preforms for optical fibers, which are also claimed.

Abstract: It is described a process based on sol-gel chemistry suitable to the production of nanocomposite materials being photoluminescent at ambient temperature, comprising silicon grains of dimension of nanometers embedded in a silica matrix.