Borosilicate Glass with Low Brittleness and High Intrinsic Strength, the Production Thereof, and the Use Thereof

Abstract

The invention relates to an alkali borosilicate glass with high strength. The alkali borosilicate glass is provided that includes: SiO2 70-86 wt %, Al2O3 0-5 wt %, B2O3 9.0-25 wt %, Na2O 0.5-5.0 wt %, K2O 0-1.0 wt %, Li2O 0-1.0 wt % and the other components 0-5.0 wt %. The proportions of the components are chosen in such a way that the weighted crosslinking index, that is, the mean number n of constraints per atom has a value greater than 2.9, preferably greater than 2.91, especially preferably greater than 2.92, and more especially preferably greater than 2.93.

Description

technical field [0001] The present invention relates to a strong alkali metal borosilicate glass as well as its manufacturing method and its use. Background technique [0002] Alkali metal borosilicate glasses are known per se and are commercially available, for example, under the trade names Duran, Borofloat 33 or also Pyrex. Here, for example Duran contains 80.2% by weight of SiO 2 , 13.4% by weight of B 2 o 3 , 2.3 wt% Al 2 o 3 , 3.5 wt% Na 2 O and 0.6 wt% K 2 O. [0003] Alkali borosilicate glasses are characterized by their low sensitivity to temperature changes and their shape stability against high temperatures. In addition, this glass exhibits outstanding chemical resistance when in contact with liquids. For this reason, this glass is used as domestic and commercial glass for a variety of applications. Such glasses are used in particular in laboratories, but can also be used in industrial plant construction. Thus, for example, glass tube lines of any lengt...

AI Technical Summary

Problems solved by technology

But this kind of glass has the following disadvantages: Due to the low linear thermal expansion coefficient, only a small prestress can be introduced into the glass on the usual air prestressing equipment, so that this kind of glass often cannot meet the desired requirements for safety glass. Requirements, such as the aforementioned DIN1249

However, Zn 0 Evaporates easily, so that it sublimes out of the glass and condenses in the flotation bath on components such as auxiliary rollers, which must therefore always be tediously cleaned during processing

In addition, the unsublimed, but reduced Zn on the flat glass surface forms deposits that are significantly detrimental to the quality of the glass.

[0010] In addition, this type of glass must contain ZrO 2 , as mentioned above, it has the following disadvantages for fire safety glass: even a small amount of unmelted ZrO 2 / ZrSiO 4 or secondary crystallized ZrO 2 / ZrSiO 4 Spontaneous fracture also occurs in case of thermal prestressing

But it has the following disadvantages: it cannot preheat the stress on common air prestressing equipment due to the high transition temperature > 600 ° C, and due to the low viscosity in the melting temperature range (in the case of about 1450 ° C, lg (η / cP)=2), with many clarifiers For example, NaCl and KCl cannot be used

Additionally, there must be a V 2 o 5 composition is not conducive to float molding, because here the V 5+ Ions are reduced in the floatation tank

In addition, V 2 o 5 It also has a detrimental effect on the high light transmittance sought

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