Schott Ag

Schott Glas

Eva Hoelzel

Hauke Esemann

Ralf Jedamzik

Thorsten Doehring

Ina Mitra

Heinrich Ostendarp

Holger Wegener

Ulrich Fotheringham

Dirk Sprenger

Wolfgang Buergel

A lithium-aluminosilicate glass ceramic is transformed by a suitable heat treatment into a glass ceramic comprising at least 80 vol.-% of keatite mixed crystals. This may be utilized for the preparation of optical or mechanical high-precision parts having a high temperature resistance, a good stability and compatibility with components consisting of metals having a small coefficient of thermal expansion based on nickel and iron, such as Invar&#xae;.

Lithium-aluminosilicate glass ceramic with high keatite content and structural member made thereof

A process for forming glass or glass ceramics is disclosed, wherein a glass ceramics form () is made from a starting glass by molding, which is transformed by a heat treatment into a keatite glass ceramic comprising predominantly keatite mixed crystals. With such a keatite glass ceramics form () formed bodies can be prepared from blank parts by sagging under gravity force at a temperature above the glass transition temperature of the blank part () (FIG.).

Method for the forming of glass or glass ceramics

A simple and economical method is described for compacting or shrinking flat glass panes. The method ensures high temperature homogeneity in the glass. First, the glass panes are cleaned and then a stack of glass panes to be treated is assembled without applying a release agent to any of the glass panes. Then the stack of glass panes is placed between ceramic panels made of silicon-infiltrated silicon carbide and this stack together with the ceramic panels is subjected to a heat treatment in a radiation furnace at temperatures ranging from 300&deg; C. to 900&deg; C. The ceramic panels have a thermal conductivity, which, in the region of the heat treatment temperature, is at least 5 times as large as that of the glass panes. The ratio of the total thickness of the ceramic panels to the height of the glass stack should be at least 1/&lgr;/40W/(mK), wherein &lgr; is the thermal conductivity of the ceramic panel at the temperatures of the heat treatment.

Method for compaction of flat glass panes

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Ober-Olm, Germany

Eva Hoelzel