Schott Glaswerke

Gerhard Weber

Helmut Dislich

Paul Hinz

Herwig Scheidler

The invention is related to a glass-ceramic article decorated with a ceramic baking finish. A SiO.sub.2 layer, about 20-200 nm thick, is placed between the decoration and the glass-ceramic material. The SiO.sub.2 layer can additionally contain, to match the refractive index to the refractive index of the glass-ceramic, up to 66.5 wt. % of oxides which change the refractive index, in particular TiO.sub.2, ZrO.sub.2, SnO.sub.2, MgO or Al.sub.2 O.sub.3. In the process to produce the decorated glass ceramic article, the SiO.sub.2 layer is preferably produced according to the known sol-gel process. Preferably, an SiO.sub.2 gel layer, optionally precondensed by a brief thermal treatment, is produced on the still-vitreous article. The decoration is applied to this gel layer and afterward the vitreous article is subjected to ceramization. The SiO.sub.2 -gel layer is converted into an SiO.sub.2 layer, and the ceramic color of the decoration is baked-in. The SiO.sub.2 layer permits, above all, the production of substantially 'halo'-free decorations with sharp contours.

Glass-ceramic article decorated with ceramic color and process for its

The invention is related to a glass-ceramic article decorated with a ceramic baking finish. A SiO.sub.2 layer, about 20-200 nm thick, is placed between the decoration and the glass-ceramic material. The SiO.sub.2 layer can additionally contain, to match the refractive index to the refractive index of the glass-ceramic, up to 66.5 wt % of oxides which change the refractive index, in particular TiO.sub.2, ZrO.sub.2, SnO.sub.2, MgO or Al.sub.2 O.sub.3. In the process to produce the decorated glass ceramic article, the SiO.sub.2 layer is preferably produced according to the known sol-gel process. Preferably, an SiO.sub.2 gel layer, optionally precondensed by a brief thermal treatment, is produced on the still-vitreous article. The decoration is applied to this gel layer and afterward the vitreous article is subjected to ceramization. The SiO.sub.2 -gel layer is converted into an SiO.sub.2 layer, and the ceramic color of the decoration is baked-in. The SiO.sub.2 layer permits, above all, the production of substantially 'halo'-free decorations with sharp contours.

Glass-ceramic article decorated with ceramic color

A pressure vessel sight glass, especially a tempered glass, is protected against the corrosive attack of normally alkaline, boiler feed water heated up to 300.degree. C., by providing the sight glass with a metallic oxide coating consisting essentially of SnO.sub.2, optionally combined with Cr.sub.2 O.sub.3. The coating is preferably applied as a sprayed solution of soluble salt convertible to the oxide.

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Schornsheim, Germany

Gerhard Weber