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AssigneeSchott Glas
InventorsPeter Nass, Roland Dudek, Juergen Naubik
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Glass or glass ceramic plates with elevated thermal resistance and process for their production. After cooling, the glass or glass ceramic plates are subjected to zone annealing, whereby the plates are divided into two zones in which annealing is done at respectively different temperatures, and whereby the zones with the elevated temperature correspond, during annealing, to the sub-areas of the finished glass or glass ceramic plates in which compression stress builds up after uneven heating corresponding to the respective specific application of the glass or glass ceramic plates. The glass or glass ceramic plates that are obtained are thus characterized in that they are divided into two sub-areas, whereby one sub-area exhibits structural compression and the other sub-area exhibits compression stress. Glass or glass ceramic plates that are resistant to breakage that is caused by uneven heating result.
A process for the production of a glass or glass ceramic plate with great resistance to breakage caused by uneven heating, wherein a glass or glass ceramic plate produced according to a conventional process including tempering is subjected to zone annealing after cooling, by exposing two different areas of the plate defining two annealing zones to a different temperature, such that the zone subjected to the respectively higher temperature is the one in the finished plate corresponding to the area where compression stress then develops in its respective specific application during uneven heating.
A glass or glass ceramic plate with high resistance to breakage caused by uneven heating of one sub-area to elevated temperature and another sub-area to lower temperature, wherein said plate is divided into two sub-areas, with one sub-area exhibiting structural compression and the other sub-area exhibiting compression stress.
Dependencies are inferred from the claim text.