Heraeus Quarzglas Gmbh & Co Kg

Heraeus Quarzglas Gmbh

Heraeus Quarschmelze Gmbh

Nigel Robert Whippey

Boris Gromann

Walter Lehmann

Michael Hünermann

Nils Christian Nielsen

Helmut Leber

Martin Trommer

Thomas Kayser

Matthias Otter

Abdoul-Gafar Kpebane

Matthias Söhn

Rainer Berg

Christian Schenk

Gerrit Scheich

Martin Arndt

Mirko Wittrin

Kathrin Wissel-Stoll

Joerg Becker

Markus Wilde

Helmut Lebert

Marcus Constantin Göbel

Bernhard Franz

Matthias SÖHN

Marcus Constantin GÖBEL

Bastian Weisenseel

A quartz glass body and a process for the preparation of a quartz glass body is disclosed. One process includes providing a silicon dioxide granulate from a pyrogenic silicon dioxide powder, making a glass melt out of the silicon dioxide granulate and making a quartz glass body out of at least part of the glass melt. In at least one process a silicon component different from silicon dioxide is added. A quartz glass body is obtainable by this process. A light guide, an illuminant and a formed body, are each obtainable by further processing of the quartz glass body.

Increase in silicon content in the preparation of quartz glass

One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, wherein the silicon dioxide granulate was made from pyrogenic silicon dioxide powder and the silicon dioxide granulate has a BET surface area in a range from 20 to 40 m/g, making a glass melt out of silicon dioxide granulate in an oven and making a quartz glass body out of at least part of the glass melt. The oven has at least a first and a further chamber connected to one another via a passage. The temperature in the first chamber is lower than the temperature in the further chambers. On aspect relates to a quartz glass body which is obtainable by this process. One aspect relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

Preparation of a quartz glass body in a multi-chamber oven

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing silicon dioxide particles, making a glass melt out of the silicon dioxide particles in an oven and making a quartz glass body out of at least part of the glass melt. The oven has a gas outlet through which gas is removed from the oven, wherein the dew point of the gas on exiting the oven through the gas outlet is less than&#xb0; C. One aspect further relates to a quartz glass body which is obtainable by this process. One aspect further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

Preparation of quartz glass bodies with dew point monitoring in the melting oven

The invention relates to a process for preparing a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt from the silicon dioxide granulate in a melting crucible, and iii.) Making a quartz glass body from at least a part of the glass melt, wherein the melting crucible is comprised in an oven and is made of at least one material comprising tungsten or molybdenum or a combination thereof. The invention further relates to a quartz glass body which can be obtained by this process. Further, the invention relates to a light guide, an illuminant and a formed body, each of which can be obtained by processing the quartz glass body further.

Preparation of a quartz glass body in a melting crucible of refractory metal

One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, wherein the silicon dioxide granulate was made from pyrogenic silicon dioxide powder and the silicon dioxide granulate has a BET surface area in a range from 20 to 40 m/g, making a glass melt out of silicon dioxide granulate in an oven and making a quartz glass body out of at least part of the glass melt. The oven has at least a first and a further chamber connected to one another via a passage. The temperature in the first chamber is lower than the temperature in the further chambers. One aspect relates to a quartz glass body which is obtainable by this process. One aspect relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

The invention relates to a process for the preparation of a quartz glass grain comprising the process steps i.) Providing a silicon dioxide granulate from a pyrogenically produced silicon dioxide powder, ii.) Making a glass melt out of silicon dioxide granulate, iii.) Making a quartz glass body out of at least part of the glass melt and iv.) Reducing the size of the quartz glass body to obtain the quartz glass grain. The invention further relates to a quartz glass grain which is obtainable by this process. The invention further relates to opaque quartz glass bodies, which are obtainable by further processing of the quartz glass grain.

Preparation of a synthetic quartz glass grain

A method for forming a hollow cylinder, in a single step, into a quartz glass tube with a large outer diameter and high dimensional stability is provided. To produce the tube, the cylinder, while rotating, is softened in portions in a heating zone which is moved at a relative feed rate Va and the softened portion is radially expanded by a centrifugal force and/or internal overpressure applied in the hollow cylinder bore so as to form a deformation zone. The radial expansion of the softened portion is carried out at a location-dependent radial expansion rate Vr, the profile of which along the deformation zone has a maximum value Vr,max which is smaller than 20 cm/min. The temperature in a rear heating portion of the heating zone, assigned to the end of the deformation zone, is lower than in a front heating portion assigned to the beginning of the deformation zone.

Method for producing a tube of glass

A method for producing a component includes joining individual wall parts, especially for producing a melting crucible for use at a high operating temperature in a crucible-pulling method for quartz glass, wherein at least two wall parts of a refractory metal or of a base alloy of a refractory metal are provided, butt-joined to form a joint and joined together by sintering at a temperature above 1500&#xb0; C. to form the component. A sealant is inserted into the joint to provide a component of improved tightness and to ensure improved sintering of the individual parts of the component. A component produced according to the method, particularly a melting crucible, particularly in a crucible pulling method for quartz glass, has the joint between the butt-joined walls closed in a gas-tight manner by a sealant.

Method for producing a component, particularly for use in a crucible pulling method for quartz glass

A method for forming a hollow cylinder, in a single step or in as small a number of steps as possible, into a quartz glass tube with a large outer diameter and high dimensional stability is provided. The cylinder, while rotating about a rotation axis, is softened in portions in a heating zone which is moved at a relative feed rate Va, and the softened portion is radially expanded by a centrifugal force and/or an internal overpressure applied in the hollow cylinder bore so as to form a deformation zone. The tube is continuously shaped with an outer diameter Dwhich is greater than that of the hollow cylinder D. The radial expansion of the softened portion is carried out at a location-dependent radial expansion rate Vr, the profile of which along the deformation zone has a maximum value Vr,max which is smaller than two times the feed rate Va.

In a known method for drawing a tubular quartz glass strand, SiO-containing starting material is fed to a melting crucible, softened therein into a viscous quartz glass mass (), and said mass is pulled vertically downward as a cylindrical quartz glass strand () through a die () provided in the bottom region of the melting crucible (), said die having a gap-shaped outlet (), which is defined by a bottom opening and a die inside part, and thereafter the quartz glass cylinder is cut to length. In order to provide a method starting from this which facilitates the production of homogeneous quartz glass cylinders, even if the lateral dimensions thereof are in the range of the inside diameters of conventional melting crucibles (), according to the invention the viscous quartz glass mass is drawn over a flow constriction () provided in an upper region of the die () and leading downward into the outlet () via a flow channel, said region facing the crucible interior, wherein the outlet has an opening width that is larger than the width of the flow constriction (), and wherein a first minimum circumscribed circle around the flow constriction () has a diameter that is a maximum of 30% of the diameter of a second minimum circumscribed circle around the quartz glass strand () to be drawn. The invention further relates to a corresponding apparatus.

Method and apparatus for producing a quartz glass cylinder

In a known method for coating a crucible for use at a high working temperature in a crucible drawing method for quartz glass, a base body wall of tungsten has applied thereto a protective layer containing a coating metal consisting of the group selected from iridium, rhenium, osmium and ruthenium. Starting therefrom, to provide a method for producing such a component exhibiting high corrosion resistance to the quartz glass melt at low material costs, it is suggested according to the invention that the protective layer should be produced from a layer material which contains tungsten and the coating metal, and in which the amount of the coating metal should be dimensioned such that it exceeds the limit amount of a coating metal-rich phase boundary of a solid mixture phase of tungsten and the coating metal, with the solid mixture phase being thermodynamically stable at the working temperature, by not more than 25 at. % (based on the total amount of tungsten and the coating metal in the layer material).

Method for coating a component for use in a crucible drawing method for quartz glass, and coated component obtained according to the method

A process is described for manufacturing vertically withdrawn pipes from quartz glass or glasses having a high content of silica with only minor diameter deviation. In an electrically heated furnace, the initial material is heated up to the softening point. A pipe is formed in a deformation zone and is downwardly withdrawn. In this deformation zone, a constant pressure difference is maintained between the pressure in the pipe interior and the pressure in a chamber and/or heating chamber. The pressure is continuously measured and controlled so as to be at a constant difference. In order to maintain a higher pressure in the pipe interior as opposed to the pressure in the chamber and/or the heating chamber, the withdrawn pipe end of the pipe to be manufactured is sealed.

Process for manufacturing quartz glass pipes having a high content of

A method for the continuous production of a tube or rod of vitreous fused silica. Silicon dioxide in particle form is heated in a crucible to the softening temperature and is withdrawn contiuously downward from a bottom outlet opening in which a shaping tool is disposed. In the annular space between the shaping tool and the bottom outlet opening the softened silicon dioxide is subjected to an electrical field. In the closed crucible, a hydrogen-containing atmosphere with a hydrogen content of at least 80% is sustained above the silicon dioxide and in the space underneath the crucible that adjoins the shaping region.

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Seligenstadt, Germany

Nigel Robert Whippey