According to one embodiment, a method for thermally treating glass articles may include holding a glass article at a treatment temperature equal to an annealing temperature of the glass article =15° C. for a holding time greater than or equal to 5 minutes. Thereafter, the glass article may be cooled from the treatment temperature through a strain point of the glass article at a first cooling rate CR1 less than 0° C./min and greater than −20° C./min such that a density of the glass article is greater than or equal to 0.003 g/cc after cooling. The glass article is subsequently cooled from below the strain point at a second cooling rate CR.sub.2, wherein |CR.sub.2|>|CR.sub.1|.

According to one embodiment, a method for thermally treating glass articles may include holding a glass article at a treatment temperature equal to an annealing temperature of the glass article =15° C. for a holding time greater than or equal to 5 minutes. Thereafter, the glass article may be cooled from the treatment temperature through a strain point of the glass article at a first cooling rate CR1 less than 0° C./min and greater than −20° C./min such that a density of the glass article is greater than or equal to 0.003 g/cc after cooling. The glass article is subsequently cooled from below the strain point at a second cooling rate CR.sub.2, wherein |CR.sub.2|>|CR.sub.1|.

A refill system includes a tempering furnace, a refill furnace which stores the molten potassium nitrate obtained by melting powdered potassium nitrate, a supply unit which supplies the molten potassium nitrate to the tempering furnace, a tempering furnace side load measuring unit which measures a load amount of the molten potassium nitrate in the tempering furnace, a refill furnace side load measuring unit which measures a load amount of the molten potassium nitrate in the refill furnace, and a central control unit which checks the load amount of the molten potassium nitrate in the tempering furnace and the refill furnace in real time, and controls the supply unit to stop supplying the molten potassium nitrate to the tempering furnace when the load amount of the molten potassium nitrate in the tempering furnace is greater than or equal to a predetermined load amount.

A refill system includes a tempering furnace, a refill furnace which stores the molten potassium nitrate obtained by melting powdered potassium nitrate, a supply unit which supplies the molten potassium nitrate to the tempering furnace, a tempering furnace side load measuring unit which measures a load amount of the molten potassium nitrate in the tempering furnace, a refill furnace side load measuring unit which measures a load amount of the molten potassium nitrate in the refill furnace, and a central control unit which checks the load amount of the molten potassium nitrate in the tempering furnace and the refill furnace in real time, and controls the supply unit to stop supplying the molten potassium nitrate to the tempering furnace when the load amount of the molten potassium nitrate in the tempering furnace is greater than or equal to a predetermined load amount.

To provide an inorganic composition article containing at least one kind selected from α-cristobalite and α-cristobalite solid solution as a main crystal phase, in which by mass % in terms of oxide, a content of a SiO.sub.2 component is 50.0% to 75.0%, a content of a Li.sub.2O component is 3.0% to 10.0%, a content of an Al.sub.2O.sub.3 component is 5.0% or more and less than 15.0%, and a total content of the Al.sub.2O.sub.3 component and a ZrO.sub.2 component is 10.0% or more, and a surface compressive stress value is 600 MPa or more.

Glass-based articles having defined stress profiles and methods for manufacturing such glass-based articles are provided. A non-limiting glass-based article comprises an outer region extending from the surface to a depth of compression, wherein the outer region is under a neutral stress or a first compressive stress, a core region under a second compressive stress, the second compressive stress defining a compression peak having a maximum compression value and a maximum width at zero stress in a range of from about 1 micrometer to about 200 micrometers, and an intermediate region disposed between the surface and the core region, wherein the intermediate region is under a tensile stress.

Glass-based articles having defined stress profiles and methods for manufacturing such glass-based articles are provided. A non-limiting glass-based article comprises an outer region extending from the surface to a depth of compression, wherein the outer region is under a neutral stress or a first compressive stress, a core region under a second compressive stress, the second compressive stress defining a compression peak having a maximum compression value and a maximum width at zero stress in a range of from about 1 micrometer to about 200 micrometers, and an intermediate region disposed between the surface and the core region, wherein the intermediate region is under a tensile stress.

The invention relates to methods of increasing the strength, especially the flexural strength, of a glass article produced from a glass material. The method includes the step of heating the glass article to a first temperature above the transformation temperature of the glass material, the step of shock cooling the glass article to a second temperature below the transformation temperature of the glass material, and the step of performing an ion exchange process at the second temperature.

The invention relates to a method for producing a glass article. The method includes the step of producing a glass body from a glass material and the further step of bringing the glass body, at a primary temperature which is at most 50 Kelvin below and at most 30 Kelvin above the Littleton softening point of the glass material, into contact with a liquid cooling agent which has a cooling agent temperature which is at least 200 Kelvin and at most 550 Kelvin below the primary temperature.

The invention relates to a method for producing a glass article. The method includes the step of producing a glass body from a glass material and the further step of bringing the glass body, at a primary temperature which is at most 50 Kelvin below and at most 30 Kelvin above the Littleton softening point of the glass material, into contact with a liquid cooling agent which has a cooling agent temperature which is at least 200 Kelvin and at most 550 Kelvin below the primary temperature.