Heraeus Quarzglas Gmbh & Co Kg

Udo Gertig

Johann Leist

Waltraud Werdecker

Heinz Fabian

Martin Arndt

Wolfgang Englisch

Helmut Leber

Hilmar Laudahn

Rainer Koeppler

Gabriele Korus

Rolf G&ouml;bel

Known is a method of producing a quartz glass crucible in which a crucible base body is provided at least in part with an inner layer in which the formation of cristobalite is induced by using a crystallization promoter. On the basis thereof, in order to provide an inexpensive method of producing a quartz glass crucible with reproducible characteristics for long service lives, it is suggested according to the invention that the crystallization promoter and a reducing substance are introduced into the inner layer.

Method of producing a quartz glass crucible

A process for manufacture of a component made of opaque synthetic quartz glass, and a quartz glass tube manufactured according to said process. The process comprises (i) providing a starting material in the form of granulated material of highly pure, synthetic SiO comprising at least partially porous agglomerates of SiO primary particles, the granulated material having a compacted bulk density of no less than 0.8 g/cm , (ii) filling the granulated material into a mold and converting it to an opaque quartz glass preform through a process of melting, and (iii) reshaping the preform in a heat reshaping process to obtain a component made of opaque quartz glass. A quartz glass tube is made of quartz glass consisting of a granulated material of synthetic SiO with a lithium content of no more than 100 wt-ppb, and the wall thickness of said component being in the range of 0.5 mm to 15 mm.

Process for manufacture of a component made of opaque synthetic quartz glass

Composite material with high resistance to temperature changes and a high density, and having an SiO -containing matrix with quartz glass grains embedded therein is produced by preparing a suspension from a particle mixture of finely divided SiO powder having at least two different particle fractions and of the quartz glass grains, forming a green compact and sintering the compact. The matrix has an SiO content of at least 99% by wt. and is formed from at least first and second particle fractions, each of which is present as granules of nanoscale, amorphous, synthetically produced SiO primary particles having a mean primary particle size of less than 100 nm. The composite material has an SiO -containing matrix with an SiO content of at least 99% by wt. It is particularly suited for applications such as starting material for producing a permanent mold for melting solar silicon.

Method of producing a composite material having a high SiO2 content, composite material obtained according to the method, and permanent mold made thereof

To facilitate the start of a process using a quartz glass crucible with a crucible body and an inner layer of quartz glass a quartz glass crucible is provided with an inner surface roughened at least in the starting zone region by multiple depressions disposed at a maximum distance of 5 mm from one another. Furthermore, a simple and inexpensive process for the manufacture of such a quartz glass crucible is described, by providing a crucible body with a smooth inner surface of quartz glass and subsequently roughening the inner layer in the starting zone region by multiple depressions disposed at a maximum of 5 mm from one another.

Quartz glass crucible and process for the manufacture of the crucible

In a known process for the production of opaque quartz glass a blank is formed from synthetic SiO granulate and is heated at a vitrification temperature to form a body of opaque quartz glass. In order to provide on this basis a process for the production of pure opaque quartz glass with a homogenous pore distribution, high density, high viscosity and a low tendency to devitrify, it is proposed according to the invention that the SiO granulate to be used is a SiO granulate ( ) composed of at least partially porous agglomerates of SiO primary particles, with a specific BET surface ranging from 1.5 m /g to 40 m /g and an apparent density of at least 0.8 g/cm . A SiO granulate ( ) suitable for the implementation of the process is distinguished in that it is formed from at least partially porous agglomerates of SiO primary particles and in that it has a specific BET surface ranging from 1.5 m /g to 40 m /g and an apparent density of at least 0.6 g/cm .

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Johannesberg, Germany

Udo Gertig