Abstract: In a known method for drawing a tubular quartz glass strand, SiO2-containing starting material is fed to a melting crucible, softened therein into a viscous quartz glass mass (27), and said mass is pulled vertically downward as a cylindrical quartz glass strand (5; 33) through a die (4; 34) provided in the bottom region of the melting crucible (1), said die having a gap-shaped outlet (25; 36), which is defined by a bottom opening and a die inside part, and thereafter the quartz glass cylinder is cut to length.

Abstract: The invention relates to a known method for drawing a quartz glass cylinder from a melt crucible comprising an inner crucible chamber extending in the direction of a center crucible axis and bounded by a side wall and a floor, wherein SiO2 granulate is fed into the melt crucible and therein softened into a quartz glass mass, and said mass is drawn vertically downward as a cylindrical quartz glass strand by means of a first draw-off device through a first draw nozzle provided in the floor of the melt crucible, and the quartz glass cylinder is cut off therefrom.

Abstract: In a known melting crucible for use in a crucible drawing method, it is provided that the interior face of the crucible wall facing a crucible interior space is covered at least partially with a protective layer made of a noble metal. The known melting crucible does have good corrosion resistance with respect to the quartz glass melt, but the material costs are high because of the expensive coating metals. In order to provide a melting crucible for use in a crucible drawing method for quartz glass that exhibits good corrosion resistance at low material costs, it is proposed that the protective layer (2) be composed of a gas-tight, oxidic material that is not subject to a phase transition in the temperature range of 20° C. to 1800° C., and that the crucible interior space (17) have a gas space (17) above the quartz glass mass (27) to be held, and that the protective layer (2) be provided exclusively on the surface of the melting crucible interior face adjacent to the gas space (17).

Abstract: In a known method for producing quartz glass that is doped with nitrogen, an SiO2 base product is prepared in the form of SiO2 grains or in the form of a porous semi-finished product produced from the SiO2 grains and the SiO2 base product is processed into the quartz glass with the nitrogen chemically bound therein in a hot process in an atmosphere containing a reaction gas containing nitrogen. From this starting point, a method is provided for achieving nitrogen doping in quartz glass with as high a fraction of chemically bound nitrogen as possible. This object is achieved according to the invention in that a nitrogen oxide is used as the nitrogen-containing reaction gas, and that a SiO2 base product is used that in the hot process has a concentration of oxygen deficient defects of at least 2×1015 cm?3, wherein the SiO2 base product comprises SiO2 particles having an average particle size in the range of 200 nm to 300 ?m (D50 value).

Abstract: 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).

Abstract: In a known method for drawing a tubular quartz glass strand, SiO2-containing starting material is fed to a melting crucible, softened therein into a viscous quartz glass mass (27), and said mass is pulled vertically downward as a cylindrical quartz glass strand (5; 33) through a die (4; 34) provided in the bottom region of the melting crucible (1), said die having a gap-shaped outlet (25; 36), which is defined by a bottom opening and a die inside part, and thereafter the quartz glass cylinder is cut to length.

Abstract: In a known method for drawing a tubular quartz glass strand, a crucible is fed with SiO2-containing start material, the start material is softened in the crucible and, as a softened quartz glass mass, is drawn vertically downwards as a tubular quartz glass strand along a drawing axis through an annular gap between an outer member and an inner member, which is arranged in a through hole of the outer member, of a drawing nozzle provided in the bottom area of the crucible.

Abstract: 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).

Abstract: 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 SiO2 comprising at least partially porous agglomerates of SiO2 primary particles, the granulated material having a compacted bulk density of no less than 0.8 g/cm3, (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 SiO2 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.

Abstract: 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 SiO2 comprising at least partially porous agglomerates of SiO2 primary particles, the granulated material having a compacted bulk density of no less than 0.8 g/cm3, (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 SiO2 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.

Abstract: A preferred embodiment of the present invention comprises a vitreous quartz pipe or container having a connector including a flange formed from at least one strip or rod-shaped piece of transparent quartz glass which is wound circumferentially around either an inner or outer surface of a portion of the pipe or container and secured to the pipe or container to thereby form a closed-ring flange. The portion of the pipe or container having the attached flange may be an open end of the pipe or container or may be a wall portion where a connector for mounting to fixtures or other fittings may be desired. This type of strip or rod-shaped piece of quartz glass can be made via a conventional pulling technique such that a strip or rod having the appropriate uniform cross-sectional shape is obtained. The prepared strips or rod-shaped pieces are then easily cut with a saw device to appropriate lengths.

Abstract: A preferred embodiment of the present invention comprises a vitreous quartz pipe or container having a connector including a flange formed from at least one strip or rod-shaped piece of transparent quartz glass which is wound circumferentially around either an inner or outer surface of a portion of the pipe or container and secured to the pipe or container to thereby form a closed-ring flange. The portion of the pipe or container having the attached flange may be an open end of the pipe or container or may be a wall portion where a connector for mounting to fixtures or other fittings may be desired. This type of strip or rod-shaped piece of quartz glass can be made via a conventional pulling technique such that a strip or rod having the appropriate uniform cross-sectional shape is obtained. The prepared strips or rod-shaped pieces are then easily cut with a saw device to appropriate lengths.

Abstract: Quartz glass component having a coating with a silicon carbide surface includes a gradient layer of silicon carbide and at least one additional constituent which is less hard and has a lower modulus of elasticity than silicon carbide and whose concentration decreases across the thickness of the layer from inside to outside. The coated component has good thermal-shock resistance and long-term stability in terms of its chemical resistance to hydrofluoric acid and nitric acid as well as to a mixture of these two acids.

Abstract: Starting from a process for producing a rod-like preform, in particular for optical fibers, in which a tubular blank whose refractive index changes, viewed in the radial direction is fed to a heating zone, is softened there, and in the softened state is shaped to give the preform, a method is described for producing preforms which are hyperpure and low in defects, in which the blank used is one whose refractive index decreases, viewed in the radial direction, from the outside inwards, starting from at least one interface which is at a sufficient distance from the outer surface of the blank, of which that part which has been softened in the heating zone is introverted apart from an outer skin, and by which the preform is formed in the longitudinal axis of the tubular blank, counter to the direction in which the latter is fed to the heating zone, and in which the remaining outer skin is drawn off as a rod in the feed direction of the blank.

Abstract: A method for producing an elongated composite glass body by melting at least two starting materials of different material compositions, feeding the starting materials to a drawing die disposed at the bottom of an externally heated melting crucible, and continuously drawing the melts vertically out of the drawing die to form a composite body laminated transverse to the drawing direction. To provide an interface free from impurities between the starting materials in the composite body and to enable the path of the interface to be freely shaped, the starting materials are fed in particle form continuously to a single melting crucible and heaped therein to form a preformed body in which one starting material lies directly next to the other starting material forming an interface line therebetween that extends substantially vertically and parallel to the drawing direction.

Abstract: A process is known for the tool-free reshaping of a tubular hollow body of amorphous, especially vitreous material to a rod by pressure constriction wherein a pressure depression below atmospheric pressure is sustained in the tubular part by continual evacuation during the constriction, while the hollow body is continually fed horizontally, at a given speed of rotation, to a heating zone, and there its viscosity is so lowered that, as a result of the pressure difference between the absolute value of pressure below atmospheric pressure in the hollow body and the external pressure acting on the hollow body, the hollow body becomes constricted to form a rod in the closing zone and the rod is continually pulled from the closing zone at a given rotatory speed; in order by such a process to produce homogeneous, rod-shaped bodies from hollow bodies in a single procedure and at reasonable cost, the outside dimensions and inside dimensions of the hollow body, the viscosity of the vitreous material in the closing zone,

Abstract: Granular silicon dioxide is placed in a treatment chamber which is heated to a temperature ranging from 700.degree. to 1300.degree. C. The chamber is then rotated for a prescribed period of time to mix the grains while a gaseous atmosphere of chlorine and/or hydrogen chloride is passed through the treatment chamber. The mixing period is followed by a resting period which is at least ten times longer than the mixing time. During the resting period the grains are exposed to a constant electric field having a strength of 600 to 1350 V/cm applied across the chamber. The foregoing cycle is repeated several times. For working the process a device is used which includes a quartz glass rotary tube into which hollow silicon carbide electrodes extend.

Abstract: 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.