Abstract: An ideal quartz glass for a wafer jig for use in an environment having an etching effect is distinguished by both high purity and high resistance to dry etching. To indicate a quartz glass that substantially fulfills these requirements, it is suggested according to the invention that the quartz glass is doped with nitrogen at least in a near-surface area, has a mean content of metastable hydroxyl groups of less than 30 wt ppm and that its fictive temperature is below 1250° C. and its viscosity is at least 1013 dPa·s at a temperature of 1200° C. An economic method for producing such a quartz glass comprises the following method steps: melting an SiO2 raw material to obtain a quartz glass blank, the SiO2 raw material or the quartz glass blank being subjected to a dehydration measure, heating the SiO2 raw material or the quartz glass blank to a nitriding temperature in the range between 1050° C. and 1850° C.

Abstract: The invention relates to a method for the economic production of a blank for a component made from laser-active quartz glass in any form or dimension. The method comprises the following method steps: a) preparation of a dispersion with a solids content of at least 40 wt. %, comprising SiO2 nanopowder and doping agents, including a cation of the rare earth metals and transition metals in a fluid, b) granulation by agitation of the dispersion, with removal of moisture to form a doped SiO2 granulate of spherical porous granular particles with a moisture content of less than 35 wt. % and a density of at least 0.95 g/cm3, c) drying and purification of the SiO2 granulate, by heating to a temperature of at least 1000° C. to form doped porous SiO2 grains with an OH content of less than 10 ppm and d) sintering or fusing the doped SiO2 grains in a reducing atmosphere to give the blank made from doped quartz glass.

Abstract: In a known method for bonding components made of material with a high silicic acid content by means of a substance to substance bond, a SiO2-containing bonding mass is formed between connecting surfaces of the components. In order to provide for cost-efficient manufacture of a thermally stable composite, the invention proposes to generate a SiO2-containing bonding mass that is generic with regard to the material with a high silicic acid content, comprising the following procedural steps: provision of a slurry containing amorphous SiO2 particles; formation of a slurry mass between the connecting surfaces which are fixed in position with regard to each other; drying of the slurry mass; and solidification of the slurry mass by heating under formation of the SiO2-containing bonding mass. A component assembly manufactured according to the method of the invention shows high temperature resistance and thermal fatigue resistance and can also be used in contamination-sensitive applications.

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: 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: 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: In a process for manufacture of dense, amorphous quartz glass granulate by production of a porous granulate from amorphous SiO2 powder and vitrification of the granulate, a porous SiO2 granulate is exposed to a fuel gas flame and is finely dispersed, heated and vitrified therein. The fuel gas flame is more flexible as concerns adjustment of the temperature than in known processes. It is in particular possible to set higher temperatures. The granulate can be exposed to very high sintering temperatures in the fuel gas flame without sintering into agglomerates. At the same time, heat resistance problems of sintering containers such as furnaces and melting pots are avoided. In addition, contamination of the SiO2 granulate by contact with the walls of sintering or vitrifying containers is eliminated. The process makes it possible to economically produce a highly pure and dense quartz glass granulate.

Abstract: To produce a free-flowing granulate which has a high bulk density and a defined particle size distribution, which generates little dust, is easy to handle, and is suitable as a starting material for quartz glass products, the mixing operation includes a first mixing phase, in which the materials to be mixed are subjected to a slow mixing action to form a coarse-grained mass, and a second mixing phase, in which the coarse-grained mass is converted to a fine-grained mass by a more intensive mixing action which grinds and compacts the grains. The content of silica powder in the materials to be mixed is adjusted at least during the second mixing phase to a value of at least 75 wt. %.

Abstract: In order to provide a temperature- and acid-resistant catalyst carrier based on a gas-pervious carrier body and a porous surface layer having a high silica content, while dispensing with a washcoat, the carrier body and the surface layer are designed as a chemically and physically homogeneous structure shaped in a single operation. The SiO.sub.2 content amounts to at least 99% by weight and has a specific surface from 5 m.sup.2 /g to 50 m.sup.2 /g. In a process for producing a catalyst carrier made of synthetic, amorphous silica particles with more than 99% by weight SiO.sub.2, a paste is prepared with the particles, a liquid, and a binder. Plastifying agents are added to the paste and the paste is continuously extruded into a monolithic greenware strand. The alkali and alkaline earth content of the paste is set at no more than 200 ppm and the greenware is cut to length and sintered at a temperature in a range between 800.degree. C. and 1400.degree. C.

Abstract: To permit using a single firing step, sintered aluminum nitride ceramic bodies provided with firmly adhering electrically conductive films or resistive layers can be produced by sintering of the green ceramic bodies and the films or layers in common, if these films or layers additionally contain a mixture of aluminum nitride and rare earth metal oxide.

Abstract: The temperature stabilization body is made of pulverized aluminum nitride with a first additive of pulverized aluminum present between 0.05% to 2%, and a grain size of under 1 micrometer, and a second additive of from 0.1% to 10% of an oxide, preferably yttrium oxide, present at about 1%--all precentages by weight, in which the mixture is ground in a ceramic ball mill to a grain size of not over 0.1 mm, subjected to cold isostatic pressure in the order of 2500 bar to form a green, pressed body, and then sintered at a sintering temperature of between 1750.degree. C. to 2000.degree. C. The heat conductivity of the densely sintered aluminum nitride body will then be at least 140 W/m .degree.K., and a heat conductivity of twice as much can be obtained, the body being non-toxic and not subject to creep under temperatures up to at least 1700.degree. C.

Abstract: A heat conductive ceramic substrate for semiconductor circuits, comprising polycrystalline aluminum nitride of high density containing as an additive boron nitride or oxides of calcium, magnesium, aluminum, titanium, zirconium, chrome, silicon, and/or rare earth metals. The boron nitride additive concentration ranges between 0.1 and 3% by weight, preferably between 0.5 and 2% by weight. The oxide additive concentration ranges between 0.1 and 5% by weight. The substrate has a significantly higher thermal conductivity than aluminum oxide substrates and is more economincal to manufacture than beryllium oxide substrates.

Abstract: A bipolar electrode has plate-like anode and cathode parts. The anode and cathode parts are secured together, edge-to-edge, to form a single element in one plane by an intermediate connecting piece. The intermediate connecting piece itself is a composite element having parts of materials which are compatible with the respectively adjacent anode and cathode. The two parts of the composite element are joined together by hot isostatic pressure, explosion-plating or diffusion-welding into the composite body, the resultant composite body then permitting welding of the respective anode and cathode plates to the respective anode part and cathode part of the composite element or body.

Abstract: A low contamination crucible for pulling monocrystals of Group III and Group V elements of the Periodic Table, comprising particularly aluminum nitride with an additive of boron nitride or a rare earth oxide. The additive concentration is up to 5% by weight, but preferably 0.5% to 3% by weight. The hardness of the crucible of the invention is 300 to 400% greater than that of undoped material subjected to the same sintering conditions.