Heraeus Quarzglas Gmbh & Co Kg

Steffen Zwarg

Martin Trommer

Udo Peper

Stefan Ochs

Ralph Sattmann

Bodo Kuehn

Mirko Wittrin

Malte Schwerin

Sven Schmidt

René Sowa

Hans-Georg Fritsche

Ralph Sattman

Thomas Krause

Frank Hoff

Michael Muschler

One aspect relates to a method for the manufacture of doped quartz glass. Moreover, one aspect relates to quartz glass obtainable according to the method including providing a soot body, treating the soot body with a gas, heating an intermediate product and vitrifying an intermediate product.

Method for the manufacture of doped quartz glass

A known method for producing synthetic quartz glass comprises: (a) reacting a carbonic silicon compound-containing raw material with oxygen in a reaction zone into SiO2 particles, (b) precipitating the SiO2 particles on a sedimentation area by forming a porous SiO2 soot body containing hydrogen and hydroxyl groups, (c) drying the porous SiO2 soot body, and (d) glazing to the synthetic quartz glass by heating the soot body up to a glazing temperature. In order to facilitate cost-efficient production of quartz glass by means of pyrolyzing or hydrolyzing a carbon-containing silicon compound using a carbon-containing raw material, the invention describes the production of a soot body with a carbon content within the range of 1 ppm by weight to 50 ppm by weight.

Method for producing synthetic quartz glass and quartz glass for use as cladding material of an optical fiber

The invention relates to a known method for the production of a cylinder from quartz glass, comprising a step, wherein an SiObody which comprises a porous SiOsoot layer and has a lower end, an upper end, and an outer casing, is sintered to form said quartz glass cylinder in a vitrification furnace, and is being held in a vertical orientation by means of a retaining device, which comprises an upper retaining element connected at the upper end of the SiObody, and a lower retaining element disposed on the lower end. In order to provide a method based thereon, by means of which even heavy bodies made of porous SiOcan be safely retained during vitrification, the invention provides that the retaining device has a dimensionally stable connecting part, which extends inside the vitrification furnace along the outer casing of the SiObody and which connects the upper and the lower retaining elements to each other.

Method for the production of a cylinder made from quartz glass using a retaining device, and retaining device

A known method for producing a cylinder of quartz glass comprises a method step in which a porous SiObody comprising a central inner bore, a lower end and an upper end is sintered in a sintering furnace zone by zone, starting from the upper end, to obtain the quartz glass cylinder, a holding device being used by means of which the SiObody is held standing in vertical orientation during a first sintering phase and suspended in a second sintering phase. Starting therefrom, to indicate a method by means of which even heavy bodies of porous SiOcan be reliably held during sintering, it is suggested according to the invention that the holding device comprises a fusion body of quartz glass which is arranged in the area of the upper end in the inner bore and which in the course of the first sintering phase fuses with the quartz glass of the SiObody and which during the second sintering phase is in operative interaction with a holding element of the holding device and together with said element contributes to a suspended holding of the SiObody to be sintered.

Method for producing a cylinder of quartz glass using a holding device and appropriate holding device for performing the method

A known method for producing synthetic quartz glass comprises the method steps: (a) forming a cylindrical SiOsoot body having an inner portion and at least one free cylinder jacket surface surrounding the inner portion; (b) thermally drying the porous soot body; and (c) vitrifying the dried soot body with formation of the cylinder from synthetic quartz glass. Starting therefrom, to indicate a method which permits a particularly flat radial distribution in the inner portion of the cylinder, it is suggested according to the invention that the dried SiOsoot body that is present after method step b) should be subjected to a homogenizing method prior to vitrification, the homogenizing method comprising the following steps: (I) heating the soot body to a consolidation temperature to form a sealing layer in the area of the at least one cylinder jacket, the sealing layer sealing the inner portion to the outside; (II) cooling the soot body from the consolidation temperature; and (III) annealing the soot body in the range of a homogenization temperature during a period of at least 5 hours so that the radial profile of the hydroxyl group concentration flattens in the inner portion.

Method for producing a cylinder from synthetic quartz glass

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Wolfen, Germany

Steffen Zwarg