Abstract:
To inhibit, or at least sharply attenuate, fluorescence of a quartz-glass velope (10) surrounding a light source (11), such as a halogen incandescent lamp, a high-pressure discharge lamp, or the like, when the quartz glass is subjected to ultraviolet (UV) radiation from the light source, and has been doped with a UV radiation absorbing material, typically a cerium, or cerium-titanium doping, the quartz-glass envelope is additionally doped with barium and boron. The barium/boron in the doping is, preferably, present in quantities of between about 0.008 and 1.25%, by weight, with reference to the undoped quartz glass. Barium metaborate can be used, optionally together with praseodymium to attenuate the fluorescence. Preferably, barium and boron form a combined doping substance with cerium, in form of a cerium aluminate and metaborate, added to the starting material for the quartz glass, and before the quartz glass is fused from quartz sand or pulverized quartz crystal.
Abstract:
This invention relates to the immobilization of toxic, e.g., radioactive, materials in a silicate glass or silica gel matrix for extremely long periods of time. Toxic materials, such as radioactive wastes containing radioactive cations, which may be in the form of liquids, or solids dissolved or dispersed in liquids or gases, are incorporated into a glass or silica gel matrix, having alkali metal, Group Ib metal and/or ammonium cations bonded to silicon atoms of said glass or silica gel through divalent oxygen linkages, by a process which involves the ion exchange of said toxic or radioactive cations with said alkali metal, Group Ib metal and/or ammonium cations to bind said toxic or radioactive cations to silicon atoms of said glass or silica gel through said silicon-bonded divalent oxygen linkages. Thereafter, the resulting glass or silica gel now characterized by toxic or radioactive cations bonded to silicon atoms through divalent oxygen linkages can be stored, or packaged in suitable containers, or disposed of as by burial, and/or sintered to collapse the pores thereof.
Abstract:
The method and apparatus for producing liquid silicon of high purity and for casting silicon. Hydrogen and a hydrogenated silane in gaseous state are mixed, preferably with a source of a small amount of oxygen, in a heated chamber producing the liquid silicon, with the exhaust gases bubbling out of the melt under a baffle. The chamber for the melt of liquid silicon preferably is lined with silicon dioxide. The liquid silicon may be used in making high purity vitreous silica and may be used in making castings of silicon. In making castings, the liquid silicon is accumulated in a second chamber and is periodically drawn from the second chamber into a third chamber which contains the mold for the casting.
Abstract:
The method and apparatus for producing liquid silicon of high purity and for casting silicon. Hydrogen and a hydrogenated silane in gaseous state are mixed, preferably with a source of a small amount of oxygen, in a heated chamber producing the liquid silicon, with the exhaust gases bubbling out of the melt under a baffle. The chamber for the melt of liquid silicon preferably is lined with silicon dioxide. The liquid silicon may be used in making high purity vitreous silica and may be used in making castings of silicon. In making castings, the liquid silicon is accumulated in a second chamber and is periodically drawn from the second chamber into a third chamber which contains the mold for the casting.
Abstract:
A process for producing transparent high-annealing-point 96% silica glass comprising the steps of depositing a carbon film on the pore walls of the glass, heating the glass and film under non-oxidizing conditions, and removing the carbon film by oxidation, is described.
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 light guide is produced by the out-diffusion of boron oxide through a free surface of a uniform borosilicate mass. The resulting structure consists of increased index silica rich regions near the surface in contact with lower index regions of a composition approaching that of the unmodified borosilicate. The out-diffusion process, generally carried out at a temperature approaching the softening point of the glass, may be applied to a borosilicate tube to result in a fiber preform. Fibers drawn from such a preform may be characterized by a silica core region, a borosilicate clad region, and a silica outer shell. Use of the procedure results in a graded index structure.
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:
1. A METHOD FOR MAKING A LOW ALKALI-CONTAINING POROUS GLASS ARTICLE HAVING A HIGH THERMAL STABILITY COMPRISING: (A) HEATING A PHASE-SEPARABLE ALKALI-BOROSILICATE GLASSS TO A TEMPERATURE SUFFFICIENT TO SEPARATE THE GLASS INTO TWO PHASES, ONE OF WHICH IS A BORATE-RICH PHASE AND IS SOLUBLE IN AN AQUEOUS SOLUTION, (B) A FIRST LEACHING OF THE PHASE-SEPARATED GLASS WITH WATER FOR A TIME AND AT A TEMPERATURE SUFFICIENT TO REMOVE A MAJOR PORTION OF THE BORATE-RICH PHASE TO FORM A POROUS GLASS HIGH IN SILICA, (C) A SUBSEQUENT LEACHING OF THE PREVIOUSLY LEACHED POROUS GLASS WITH AN ACID FOR A TIME AND AT A TEM-
PERATURE SUFFICIENT TO REMOVE SUFFICIENT ALKALI AND BORATE NOT REMOVAL IN THE FIRST LEACHING TO PROVIDE A LOW ALKALI-BORATE CONTAINING MICROPOROUS GLASS STRUCTURE HAVING A HIGH THERMAL STABILITY.
Abstract:
An intimate mixture of a boric oxide source compound and colloidally subdivided amorphous silica is slowly heated to evolve all moisture and boric oxide source decomposition products. The mixture is then heated to a final temperature between 500* and 900* C. to form a borosilicate glass powder directly, or to form a borosilicate glass agglomerate which may readily be crushed to a powder.