Schott Ag

Stefano Merolla

Manfred Borens

Karsten Von Westernhagen

Joerg Witte

Joachim Kuester

Franz-Peter Eckes

Stefan Postrach

Janus Zborowski

Karsten V Westernhagen

Gerald Wasem

Marcus Holla

To provide a material for use at high temperatures of several 100&#xb0; C. which is simple and quick to produce, the invention provides a composite having a layer structure and a process for producing it, which comprises the following steps:

Layer material for high-temperature use

A process is disclosed for simple and rapid production of a shaped body comprising fused silica and a shaped body which leads to virtually no contamination of a melt in contact with the shaped body even at high temperatures. The disclosed process comprises the steps of: a) provision of fused silica in the form of essentially amorphous SiOgrains of which not more than 5% have a diameter greater than 15 mm, b) addition of water to the fused silica grains to produce a slip, c) casting of the slip into a mold which comprises a hollow body having the inverse shape of the shaped body to be produced, and d) drying of the slip to give an intermediate body, which is then sintered and cooled. A shaped body producible in accordance with the aforementioned process is also disclosed, which comprises at least 99.0 mol % of SiO.

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The method provides an improved quartz glass body, especially an improved quartz glass crucible for melting non-metals, non-ferrous metals, or silicon. The quartz glass body is made by a method in which a quartz glass-water mixture is supplied to a gypsum casting mold comprising an outer part and an inner part, dried in the gypsum mold, and put under an overpressure via a system of ducts in the form of textile tubes embedded in the mold during the drying. Later a resulting green glass body is removed from the mold. At least a portion of the shaping surfaces of the inner part of the gypsum mold are surfaces of a water-impermeable substance. The method provides a cast body with a reduced tendency to crack and with a smaller open porosity.

Method and casting mold for manufacturing a quartz glass body

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Mainz, Germany

Stefano Merolla