Abstract: To optimize a known method for producing a composite body from a basic body of opaque quartz glass and a dense sealing layer, in such a way that the basic body can be provided with the dense sealing layer without any significant changes and deformations in the opaque material being noticed, the invention suggests a method comprising the following steps: (a) producing the basic body by using a first slip which contains larger amorphous SiO2 particles; (b) providing a second slip which contains smaller amorphous SiO2 particles and the composition of which differs from that of the first slip at least in that it contains SiO2 nanoparticles in the range between 0.2% by wt. to 15% by wt. and which is distinguished by a relatively low vitrification temperature; (d) producing a slip layer from the second slip on a surface of the basic body, drying the slip layer, and (e) subsequently vitrifying the slip layer with formation of the dense sealing layer.

Abstract: To optimize a known method for producing a composite body from a basic body of opaque quartz glass and a dense sealing layer, in such a way that the basic body can be provided with the dense sealing layer without any significant changes and deformations in the opaque material being noticed, the invention suggests a method comprising the following steps: (a) producing the basic body by using a first slip which contains larger amorphous SiO2 particles; (b) providing a second slip which contains smaller amorphous SiO2 particles and the composition of which differs from that of the first slip at least in that it contains SiO2 nanoparticles in the range between 0.2% by wt. to 15% by wt. and which is distinguished by a relatively low vitrification temperature; (d) producing a slip layer from the second slip on a surface of the basic body, drying the slip layer, and (e) subsequently vitrifying the slip layer with formation of the dense sealing layer.

Abstract: In a device (5) for the manufacture of a quartz glass crucible (2), one section (14, 15) of a wall (13) of the rotating quartz glass crucible (2) is heated at one time by means of at least two electrode arrangements (7, 8) distributed uniformly at the circumference of the quartz glass crucible (2) and generating a first and another electric arc. By providing several electrode arrangements (7, 8), the cooling-down phase of the sections (14, 15) until their reaching the subsequent heating zone (11, 12) can be shortened, and thus an undesirable high temperature difference of the wall (13) can be avoided. Moreover, the required thermal output of each individual electrode arrangement (7, 8) can be reduced, so that evaporation phenomena and connected bubble formation can be reduced. In addition to the higher quality that can be reached in this way, the duration of the manufacturing process is reduced.

Abstract: Disclosed is a component made of quartz glass, especially a crucible. A blank is provided with a stabilizing layer exhibiting a higher softening temperature than quartz glass. In order to provide a quartz glass component which is characterized by high mechanical and thermal resistance, in addition to providing a simple, cost-effective method for the production of said component, the chemical composition of the stabilizing layer (3; 6; 7; 38) is different from that of the quartz glass and said layer is applied by means of heat injection. The inventive method is characterized in that a stabilizing layer (3; 6; 7; 38) whose chemical composition is different from that of quartz glass is applied by heat injection.

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: In order to provide a quartz glass crucible distinguished by high purity, high opacity and/or low transmissibility in the IR spectrum, it is proposed on the basis of a known quartz glass crucible of opaque quartz glass with a crucible body symmetrical in relation to a rotational axis, an outer zone (3) of opaque quartz glass transitioning radially toward the inside into an inner zone (2) of transparent quartz glass and with a density of at least 2.15 g/cm3, that according to the invention, the crucible body (1) be made of a synthetic SiO2 granulate with a specific BET surface ranging from 0.5 m2/g to 40 m2/g, a tamped volume of at least 0.8 g/cm3 and produced from at least partially porous agglomerates of SiO2 primary particles.

Abstract: Composite material with high resistance to temperature changes and a high density, and having an SiO2-containing matrix with quartz glass grains embedded therein is produced by preparing a suspension from a particle mixture of finely divided SiO2 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 SiO2 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 SiO2 primary particles having a mean primary particle size of less than 100 nm. The composite material has an SiO2-containing matrix with an SiO2 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.

Abstract: Known is a method of producing a composite material having an SiO2-containing matrix in which quartz glass grains are embedded, wherein a suspension is prepared from a particle mixture of finely divided SiO2 powder having at least two different particle fractions and of the quartz glass grains, a green compact is formed therefrom and said compact is sintered. To permit an inexpensive production of a composite material having a high resistance to temperature changes together with a high density, it is suggested according to the invention that the matrix should have an SiO2 content of at least 99% by wt. and should be formed from at least a first (33) and a second (35) particle fraction, each of the particle fractions being present as granules of nanoscale, amorphous, synthetically produced SiO2 primary particles (2) having a mean primary particle size of less than 100 nm.

Abstract: 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.

Abstract: In order to provide a quartz glass crucible distinguished by high purity, high opacity and/or low transmissibility in the IR spectrum, it is proposed on the basis of a known quartz glass crucible of opaque quartz glass with a crucible body symmetrical in relation to a rotational axis, an outer zone (3) of opaque quartz glass transitioning radially toward the inside into an inner zone (2) of transparent quartz glass and with a density of at least 2.15 g/cm3, that according to the invention, the crucible body (1) be made of a synthetic SiO2 granulate with a specific BET surface ranging from 0.5 m2/g to 40 m2/g, a tamped volume of at least 0.8 g/cm3 and produced from at least partially porous agglomerates of SiO2 primary particles.

Abstract: In a device (5) for producing a quartz glass crucible (2) a section (14, 15) of a wall (13) of a rotating quartz glass crucible (2) is heated by at least two electrode arrangements (7, 8) which are evenly spaced along the periphery of the quartz glass crucible (2) and create a first and a second electric arc. The use of a plurality of electrode arrangements (7, 8) allows a reduction of the cooling phase of the section (14, 15) i.e. the time until it reaches the next heating zone (11, 12), so that undesirably high temperature differentials in the wall (13) are prevented. At the same time the required heat output of each individual electrode arrangement (7, 8) can be reduced so that vaporization and the concurrent bubble formation is reduced. In addition to the higher levels of quality attainable hereby, the duration of the manufacturing process is also reduced.

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: Based on a known process for the manufacture of opaque quartz glass, by mixing SiO2 particles and an additive which is volatile at a melting temperature, forming a body and melting said body with an advancing melt front forming in the body, it is proposed according to the invention that in order to reduce the danger of contamination, a body (1) be formed with an inner bore (6) and be heated in such a manner that the melt front (10) advances from the inner bore (6) to the outside. The article of pure opaque quartz glass according to the invention has high resistance to temperature change, high mechanical strength and good chemical durability. It is distinguished by an opening (6) enclosed by an inner wall (9), with an inner SiO2 surface layer (15) having a layer thickness ranging from 30 mm to 500 mm and a density of at least 2.15 g/cm3.

Abstract: In a known process for the production of opaque quartz glass a blank is formed from synthetic SiO2 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 SiO2 granulate to be used is a SiO2 granulate (21; 31) composed of at least partially porous agglomerates of SiO2 primary particles, with a specific BET surface ranging from 1.5 m2/g to 40 m2/g and an apparent density of at least 0.8 g/cm3. A SiO2 granulate (21; 31) suitable for the implementation of the process is distinguished in that it is formed from at least partially porous agglomerates of SiO2 primary particles and in that it has a specific BET surface ranging from 1.5 m2/g to 40 m2/g and an apparent density of at least 0.6 g/cm3.

Abstract: A quartz glass component for a reactor chamber, especially of a plasma etching device, comprises a substrate of a first quartz glass quality with an inner surface having an average roughness depth Ra of more than 1 &mgr;m, facing the inside of the reactor. To minimize particles in the reactor chamber, and to give the inner surface high adhesiveness for layers deposited on it and a long service life, a roughness zone is formed on the substrate by an open pore bubble layer made of a second quartz glass quality. The quartz glass component may be made by forming a blank from a granulate containing SiO2, and partial or complete vitrification of the blank by heating to a temperature above 1,000° C. During the forming of the inner surface of the blank, an additional constituent is added to the granulate containing siO2 in a roughness zone. The additional constituent reacts during the vitrification to release a gas, which forms a bubble layer during vitrification of the roughness zone.