Abstract:
A shaped body of amorphous silicon dioxide, which has a chemical purity of at least 99.9% and a cristobalite content of at most 1% and which is impermeable to gas, is known. To provide shaped bodies of amorphous silicon dioxide which have a high precision, which can be small or large in size and of simple to complicated shape, which have a chemical purity of at least 99.9%, are impermeable to gas above wall thicknesses of 1 mm, which have a high cold flexural strength, low thermal conductivity and low radiation of heat, which are thermal shock resistant and can be exposed repeatedly or also long-term to temperatures in the range from 1000.degree. to 1300.degree. C. and which can be welded in a sharply delineated manner without spreading joins and which have a low spectral transmission from the ultraviolet to the middle infrared spectral region, the shaped body is opaque, contains pores, at a wall thickness of 1 mm has a direct spectral transmission which is virtually constant in the wavelength range from .lambda.=190 nm to .lambda.=2650 nm and is below 10%, and it has a density which is at least 2.15 g/cm.sup.3. A process for producing such shaped bodies is also provided.
Abstract:
An aqueous slurry comprising an intimate mixture of colloidal silica, (preferably an amorphous, precipitated, hydrated silica), caustic potash, boric acid and alumina is first prepared and then dried. The dried aggregates are thereafter crushed, calcined and rapidly quenched. It is preferred to dry the slurry in a spray drier and thereafter omit crushing after drying and to calcine the dried admixture by means of a plasma arc so that the mixture is rapidly quenched after calcination. The calcined mixture is introduced into a crusher, such as a ball mill, with a carbonaceous cellulating agent and reduced to a fine pulverulent material. The pulverulent material is then cellulated in a cellulating furnace to form cellular borosilicate bodies. Where desired, the calcined material may be utilized as a ceramic frit.
Abstract:
Thermally stable, mechanically strong microporous glass articles with large pore volumes, surface areas, and varying pore sizes, and methods for making such articles are disclosed. In particle form, such as beads, the microporous glass articles are useful as catalyst supports in applications such as petroleum catalytic refiners, chemical processes and motor vehicle catalytic mufflers. The mechanical strength and the dimensional stability of the microporous glass articles at elevated temperatures can be improved if the articles are preshrunk, such as by brief exposure to high temperatures, before their intended use, and can be improved even further if treated with certain metal oxides.
Abstract:
A chemical vapor deposition method for producing a porous organosilica glass film comprising: introducing into a vacuum chamber gaseous reagents including at least one precursor selected from the group consisting of an organosilane and an organosiloxane, and a porogen that is distinct from the precursor, wherein the porogen is a C4 to C14 cyclic hydrocarbon compound having a non-branching structure and a degree of unsaturation equal to or less than 2; applying energy to the gaseous reagents in the vacuum chamber to induce reaction of the gaseous reagents to deposit a preliminary film on the substrate, wherein the preliminary film contains the porogen; and removing from the preliminary film substantially all of the labile organic material to provide the porous film with pores and a dielectric constant less than 2.6.
Abstract:
A method for manufacturing a porous-glass material for optical fiber performed in a reaction apparatus having a plurality of burners for producing glass particles toward a initial base material and a ventilation mechanism at a position opposed to the plurality of burners, the method comprises the steps of (a) moving the plurality of burners back and forth along a initial base material, (b) depositing the glass particles produced by the flame hydrolysis reaction of the glass raw material around the initial base material, (c) starting the deposition of a next porous-glass material without removing soot stuck to the inside of the chamber after the deposition of the glass particles is completed. Under the above condition, the inside pressure of the chamber is preferably adjusted within the range of −80 Pa≦Pmin≦−40 Pa, which is a pressure differential between the inside and outside of the chamber. (Hereinafter referred to a pressure differential between the inside and outside of the apparatus)
Abstract:
A transparent amorphous silicon dioxide film containing many fine voids, characterized in that the refractive index (for light at λ=500 nm) is in the range of 1.01 to 1.40 and that 80 vol. % or more of the fine voids have a diameter of 5 nm or less, has a low refractive index and excellent physical strength such as high scratch resistance, so that it is advantageously employable as an optical film of an optical device for various uses.
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. A process for producing a quartz glass crucible of this kind is distinguished according to the invention in that for the production of the crucible a SiO2 granulate is used which was formed from at least partially porous agglomerates of synthetically manufactured SiO2 primary particles and that it has a specific BET surface ranging from 0.5 m2/g to 40 m2/g and a tamped volume of at least 0.8 g/cm3, the heating effected in such a way that a vitrification front advances from the inside outward while an inner zone (4) of transparent quartz glass is being formed.
Abstract:
A shaped body of amorphous silicon dioxide, which has a chemical purity of at least 99.9% and a cristobalite content of at most 1% and which is impermeable to gas, is known. To provide shaped bodies of amorphous silicon dioxide which have a high precision, which can be small or large in size and of simple to complicated shape, which have a chemical purity of at least 99.9%, are impermeable to gas above wall thicknesses of 1 mm, which have a high cold flexural strength, low thermal conductivity and low radiation of heat, which are thermal shock resistant and can be exposed repeatedly or also long-term to temperatures in the range from 1000.degree. to 1300.degree. C. and which can be welded in a sharply delineated manner without spreading joins and which have a low spectral transmission from the ultraviolet to the middle infrared spectral region, the shaped body is opaque, contains pores, at a wall thickness of 1 mm has a direct spectral transmission which is virtually constant in the wavelength range from .lambda.=190 nm to .lambda.=2650 nm and is below 10%, and it has a density which is at least 2.15 g/cm.sup.3. A process for producing such shaped bodies is also provided.
Abstract:
The high-purity, opaque quartz glass containing 3.times.10.sup.6 -9.times.10.sup.6 of closed cells having an average size of 20-40 .mu.m per 1 cm.sup.3, a ratio of closed cells having sizes of 100 .mu.m or more to the whole of cells being 1% or less, thereby showing 5% or less of linear transmittance for near infrared rays (.lambda.=900 nm) at a thickness of 1 mm is produced by compacting amorphous silica powder having an average particle size of 0.5-10 .mu.m, in which each of impurities selected from Li, Na, K, Fe, Ti and Al is 1 ppm or less, if any, and sintering the resultant green body at 1730.degree.-1850.degree. C.
Abstract:
A UV sensor having a photodetector for measurement of UV radiation, an SiO.sub.2 -containing dispersive element disposed ahead of the photodetector in the direction of incident UV radiation and an optional housing having an entry opening for UV radiation. The dispersive element contains quartz glass with interiorly disposed boundary surfaces, the orientations of which are statistically homogeneously distributed.