Abstract:
A process for the production of a self-supporting glass film is described. The method includes the steps of preparing a mixture containing a colloidal silica sol, at least one alkanolamine organic additive and an organic binder; coating the mixture onto a base material; drying the coated mixture to form a precursor film on the base material; releasing the precursor film from the base material; and firing the released precursor film to form a self-supporting glass film. Self-supporting glass films produced by the disclosed process are also described.
Abstract:
A quartz powder, preferably, a synthetic quartz powder prepared by the sol−gel method, which while heated from room temperature to 1700˚C, generates a gas containing CO and CO 2 in amounts of 300 nanoliter/g or less and 30 nanoliter/g or less, respectively; a method for preparing the quartz powder; and a formed glass article prepared by melting the quartz powder and forming the resultant molten quartz. The quartz powder has extremely high purity and quality and the formed glass article contains an extremely small amount of foam.
Abstract:
An improved sol-gel process is disclosed for producing a synthetic silica glass article, in which a sol is formed having a silica loading as high as 34 to 40 %. This high loading is achieved by introducing an aqueous colloidal silica suspension into a silicon alkoxide solution and slowly stirring the mixture together, during which time the mixture hydrolyzes and the colloidal suspension is broken down by chemical reaction. This produces a hydrolyzed sol incorporating a suspension of very fine aggregates of colloidal particles, having particle sizes less than about 10 microns. The need for a stabilizing agent and/or continuous ultra-sonicating or violently stirring the sol is eliminated. One application of the process of the invention is in making silica photoblanks exhibiting very high optical transmission at UV wavelengths. For such applications, the silica powder is purified using a chlorination step prior to its being made into the aqueous colloidal silica suspension. In addition, warpage of the silica photoblanks is avoided by using silicon carbide plates as weights during sintering.
Abstract:
The invention relates to a crucible characterized in that said crucible is of high purity and high opacity or exhibits low transmission characteristics in the IR range and is derived from a quartz glass crucible known in prior art. Said crucible known in prior art has a crucible body which is symmetrical about a rotational axis and said body is made of opaque quartz glass, whereby the crucible has an outer zone (3) made of opaque quartz glass which projects radially inwards to an inner zone (2) made of transparent quartz glass having a density of at least 2.15 g/cm . The crucible body (1) is made of a synthetic SiO2 granulate with a specific surface (according to BET) in the range of 0.5 m /g to 40 m /g and having a stamp density of at least 0.8 g/cm and is produced from an at least partially porous agglomerate of SiO2 primary particles. A method for producing said quartz glass crucible is characterized according to the invention in that during the production of said crucible, an at least partially porous agglomorate of synthetically produced SiO2 granulate made of SiO2 primary particles is produced having a specific surface (according to BET) in the range of 0.5 m /g to 40 m /g and a stamp density of at least 0.8 g/cm . Heating is performed in such a manner that a vitrification front progresses from the inside to the outside of an inner zone (4) made of transparent quartz glass.
Abstract:
A method for preparation of a synthetic vitreous silica which comprises a first step comprising ejecting a silicon compound together with a combustion gas containing oxygen and hydrogen from a burner, to hydrolyze the silicon compound in an oxyhydrogen flame and form vitreous silica particles, and depositing the silica particles onto a target being opposed to the burner, to thereby produce a transparent synthetic vitreous silica ingot, a second step of heating the silica ingot to a first holding temperature of 900 DEG C or higher and holding it at the temperature, and then cooling it to a temperature of 500 DEG C or less by a temperature-decreasing rate of 10 DEG C/hr or less, and a third step of heating the resultant glass ingot to a second holding temperature of from 500 DEG C to 1100 DEG C and holding it at the temperature, and then cooling it to a temperature 100 DEG C lower than the second holding temperature by a temperature-decreasing rate of 50 DEG C/hr or greater.
Abstract:
An object of the present invention is to provide silica glass having high purity, high heat resistance, large coefficient of thermal expansion, and low light transmittance and a method of producing the same. Another object of the present invention is to provide a silica glass jig with a vapor-deposited film thereon. Therefore cristobalite-contained silica glass wherein alpha -cristobalite in the shape of a small sphere or a small, round-edged or sharp-edged, three-dimensional region is dispersed in the silica glass matrix, the diameter of each alpha -cristobalite sphere or region is in the range of 0.1 mu m to 1000 mu m, and a content of the alpha -cristobalite is at least 10 wt.%. A method of producing the cristobalite-contained silica glass by heating a mixture of two kinds or more of crystalline silicon dioxide powder the melting points of which silicon dioxide are different from each other by 20 DEG C or more wherein the mixture contains the silicon dioxide having the highest melting point at a content in the range of 10 wt.% to 80 wt.% and is heated at temperatures in the range of the lowest melting point of the ingredients to a temperature lower than the highest melting point. The silica glass jig is made of the cristobalite-contained silica glass and the surface of the jig is covered with a vapor-deposited thin film which has a property of being resistant to plasma etching, and which is made of a material of almost the same coefficient of thermal expansion as that of the silica glass. The silica glass jig has no chance to generate particles therefrom and thereby to contaminate a silicon wafer.
Abstract:
Synthetic quartz glass powder obtained by the sol-gel method and containing at most five black particles per 50g of the powder. A high-quality quartz glass molding is produced by melt molding the powder while extremely suppressing foaming.
Abstract:
An improved sol-gel process for fabricating large, crack-free gel monoliths (e.g., of silica) is described in which a specially-tailored gel microstructure is provided by adjusting the relative concentrations of an alcohol diluent (e.g., ethanol) and/or one or more catalysts (e.g., HC1 and HF). Controlled variations in the gel's average pore radius, bulk density, rupture modulus, and elastic modulus over a wide range can be tailored in this fashion. This enables the process to be optimized for the particular application involved.