A method for making high optical quality multicomponent chalcogenide glasses without refractive index perturbations due to striae, phase separation or crystal formation using a sealed ampoule with chemical components enclosed inside, a two-zone furnace, a convection heating/mixing step, and multiple fining steps. Initially, the sealed ampoule is oriented vertically within the two-zone furnace and heated to melt the chemical components contained within, and a temperature gradient is created between the top zone and the bottom zone such that the bottom zone has a higher temperature. This temperature gradient causes convection currents within the viscous liquid until it is sufficiently mixed due to the convective flow. Then the temperature gradient is reversed such that the top zone now has a higher temperature and the convective flow ceases. The furnace temperatures are then reduced over a period of time, with holds at multiple temperatures for fining and cooling to form a solid glass.

A method for making high optical quality multicomponent chalcogenide glasses without refractive index perturbations due to striae, phase separation or crystal formation using a sealed ampoule with chemical components enclosed inside, a two-zone furnace, a convection heating/mixing step, and multiple fining steps. Initially, the sealed ampoule is oriented vertically within the two-zone furnace and heated to melt the chemical components contained within, and a temperature gradient is created between the top zone and the bottom zone such that the bottom zone has a higher temperature. This temperature gradient causes convection currents within the viscous liquid until it is sufficiently mixed due to the convective flow. Then the temperature gradient is reversed such that the top zone now has a higher temperature and the convective flow ceases. The furnace temperatures are then reduced over a period of time, with holds at multiple temperatures for fining and cooling to form a solid glass.

The present invention provides for synthesizing high optical quality multicomponent chalcogenide glasses without refractive index perturbations due to striae, phase separation or crystal formation using a two-zone furnace and multiple fining steps. The top and bottom zones are initially heated to the same temperature, and then a temperature gradient is created between the top zone and the bottom zone. The fining and cooling phase is divided into multiple steps with multiple temperature holds.

The present invention provides for synthesizing high optical quality multicomponent chalcogenide glasses without refractive index perturbations due to striae, phase separation or crystal formation using a two-zone furnace and multiple fining steps. The top and bottom zones are initially heated to the same temperature, and then a temperature gradient is created between the top zone and the bottom zone. The fining and cooling phase is divided into multiple steps with multiple temperature holds.

The present invention relates to a black quartz glass consisting of a composition comprising 63 to 65 mass % of SiO.sub.2, 18 to 24 mass % of TiO.sub.2, and 12 to 17 mass % of Al.sub.2O.sub.3, wherein the sum of SiO.sub.2, TiO.sub.2 and Al.sub.2O.sub.3 is 100 mass %; and to a method for producing black quartz glass comprising: mixing 63 to 65 mass % of a SiO.sub.2 powder, 18 to 24 mass % of a TiO.sub.2 powder and 12 to 17 mass % of an Al.sub.2O.sub.3 powder, filling the mixed powder into a mold and then melting at a maximum temperature of 1700 to 1900 C. in an oxygen-free atmosphere, and cooling to room temperature to obtain the black quartz glass; and further to a product comprising a black quartz glass member made of the black quartz glass. The present invention allows to provide a black quartz glass which has an excellent light-shielding property, has no risk of causing contamination in a step of using it, has sufficient color uniformity when the size is enlarged, and is capable of producing a large ingot, and to provide a method for producing the black quartz glass with excellent productivity even in the large ingot, and to provide a black quartz glass product made of the black quartz glass.

The subject matter described herein includes a method of manufacturing colored borosilicate glass including, preparing a raw material composition to form a homogenous powdered mixture, placing the homogenous powdered mixture in a container, heating the mixture to a temperature of 2500-3000 F., charging the container with additional homogenous powdered mixture until the container is full, melting the homogenous powdered mixture until it forms molten borosilicate glass, and refining the molten borosilicate glass between 2800-3200 F. to allow air to escape and the glass to fully homogenize.

A method for removing bubbles from molten glass is provided and involves subjecting the surface of the molten glass to at least one fining sequence wherein the fining sequence comprises subjecting the surface of the molten glass to a sub-atmospheric pressure (relative vacuum less one atmosphere of pressure) for a time followed by subjecting the surface of the molten glass to super-atmospheric gas pressure (greater than one atmosphere of pressure) for additional time. The fining sequence can be repeated as needed to produce a high quality optically clear glass that is substantially free of bubbles.

The invention relates to a method for the preparation of a lithium silicate glass or a lithium silicate glass ceramic which comprise cerium ions and are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth. The invention also relates to a lithium silicate glass and a lithium silicate glass ceramic which can be obtained using the method according to the invention, the use thereof as dental material and in particular for the preparation of dental restorations, as well as a glass-forming composition which is suitable for use in the method according to the invention.

The invention relates to a method for the preparation of a lithium silicate glass or a lithium silicate glass ceramic which comprise cerium ions and are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth. The invention also relates to a lithium silicate glass and a lithium silicate glass ceramic which can be obtained using the method according to the invention, the use thereof as dental material and in particular for the preparation of dental restorations, as well as a glass-forming composition which is suitable for use in the method according to the invention.

A production apparatus making continuously curved crystalline glass as a cover or container includes a melting device, a drainage device, a molding device, and a crystallizing device. The melting device melts glass raw material to form a glass melt. The drainage device drains the glass melt to the molding device. The molding device includes a rotating table and a plurality of molding molds thereon. Each molding mold can be moved toward or away from the drainage device by the rotating table. Each molding mold has a molding cavity. At least one part of the molding cavity includes a plane, and at least one part of the molding cavity includes a curved surface to extrude the glass melt with such different surface forms. The crystallizing device crystallizes the curved glass member to achieve the curved crystallized glass member. A method for manufacturing such glass is also provided.