High-performance glass ceramics and method for producing high-performance glass ceramics

Abstract

The invention relates to high-performance glass ceramics and to a method for producing said glass ceramics. A glass or glass ceramic material is used as starting material, which may be a lithium-aluminium silicate (LAS) having a composition within the following limit values in weight %: 60-73 SiO2, 15-25 Al2O3, 2.2-5 Li2O, 0-5 CaO+SrO+BaO, 0-5 TiO2, 0-5 ZrO2, >0-4 ZnO, 0-3 Sb2O3, >0-3 MgO, 0-3 SnO2, 0-9 P2O5, 0-1.5 As2O3, >0-1 Na2O, >0-0.5 K2O, >0-1.2 Na2O+K2O and 0-1 colouring oxides. The green body is subjected to a thermal treatment for ceramization: room temperature 660 DEG C at a heating rate of > 15 K / min, e.g. within 11 min at 58 K / min; up to about 20 min process time with the slow reduction of the heating rate to zero; 30 min constant at 790 DEG C; heating to maximum temperature (1080-1300 DEG C) at >10 K / min, e.g. 30 K / min; no holding time at maximum temperature; cooling to 400 DEG C at a cooling rate of 15-350 K / min; cooling to room temperature. During tempering the temperature at the workpiece is preferably registered by sensors having a response time of less than 10 s. The kiln regulates the temperature accordingly with a response time of at most 10 s. The LAS glass ceramics produced in this way is characterised in the non-reworked state or processed state inter alia by a high impact resistance in the falling ball test of more than 15 cm (e.g. 56 +- 13 cm), an acid resistance according to DIN 12116 of 1 or 2 (e.g. 1) and a resistance to temperature differences (RTD) of more than 700 DEG C. It is suitable as inter alia an oven cladding, oven window, stove top, chemically resistant laboratory vessel, white goods, translucent article with UV protection, etc.

Description

technical field [0001] The present invention relates to glass ceramics, their preparation and use, and in particular to high performance glass ceramics with significantly improved physical and chemical properties. Background technique [0002] Various methods are known from the prior art for producing glass ceramics which in particular optimize the mechanical or product properties of glass ceramic products. The basic starting point of the optimization concept is to change the composition of the initial glass or to change the heating rate, which can be performed faster or slower. [0003] When changing the composition of the raw glass, the difficulty in optimizing the solution often lies in the processability of the glass-ceramic, wherein, for example, low processing temperatures are sought. However, the composition also has an influence on the properties of the glass-ceramic, since the composition also influences the transition enthalpy and thus the transition speed of the ...

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