Abstract: In a known drawing method for producing a cylindrical component from quartz glass, a quartz glass strand (2) is continuously drawn off from a softened quartz glass composition (13) vertically downwards in the drawing direction (3), a piece (15) with a weight G is detached from the free end of the strand at a time t1 and the cylindrical component is produced from the piece (15). When the piece (15) is detached, there may be a sudden reduction in weight, which leads to fluctuations in the thawing-off control. To counteract this, it is proposed according to the invention that a weight compensating force which acts counter to the drawing direction (3), increases over time and completely or partially compensates for the weight G of the piece (15), is applied to the piece to be detached at a time t0 before t1.

Abstract: Provided is an apparatus for manufacturing an optical element, and a method of manufacturing an optical element, whereby variance of dropping positions of glass droplets can be suppressed even with a low-cost and simple configuration. The positions where the glass droplets are discharged from a discharged port 51c are controlled by having a predetermined force applied to the glass droplets from the wall surface of a passage 51b of a correcting member 51 in a non-contact manner, the glass droplets passing through the passage 51b. Therefore, variance of dropping positions of the glass droplets can be suppressed without surrounding the whole manufacturing apparatus. Consequently, a highly accurate optical element can be manufactured with the low-cost and simple configuration.

Abstract: Refractory materials are provided which contain P2O5/R2O3 constituents, where R is Y, Sc, Er, Lu, Yb, Tm, Ho, Dy, Tb, Gd, or a combination thereof, and/or V2O5/R?2O3 constituents where R? is Y, Sc, one or more rare earth elements, or a combination thereof. In certain embodiments, the refractory materials are xenotime-type materials and/or xenotime-stabilized zircon-type materials. The refractory materials can be used in the manufacture of glass and glass-ceramics. For example, the refractory materials, especially those that contain P2O5/R2O3 constituents, can be used as forming structures (“isopipes”) in the fusion process for making flat sheets of glass such as the glass sheets used as substrates in the manufacture of flat panel displays.

Abstract: The present invention relates to a process for manufacturing flat sheets of a glass-based material and to a device associated with the process.

Abstract: A process and apparatus for removing molten glass from flow channels for the transport of production glass that are installed between a melting furnace and an extraction point for the production glass. The flow channel has a glass-resistant inner lining. A drainage unit for bottom glass is installed upstream of the extraction point for the production glass. In order to keep electrodes away from the molten glass, but still maintain a local and temporal influence on the temperature profile within the cross section, the inner lining, at least in the area of the drainage unit, of is formed of a fusion cast electrically conductive material which has a drainage opening for the bottom glass with a drainage slit above it. At least two electrodes are installed on opposite sides of the flow channel and the drainage unit for the bottom glass.

Abstract: The invention relates to a device for heating up extrusion dies prior to their installation in an extruder, whereby the dies are heated up to a prescribed temperature and kept at this temperature. The device is characterized in that it comprises a gas-tight and thermally insulated oven housing (50) that has at least one charging and discharging opening (70) with an oven cover (40) and, inside the oven housing, there is an impact nozzle field (20) into which a die (90) can be placed, and in that the device (10) is provided with a heating means (100) that heats up a fluid that flows through the openings (110) of the impact nozzle field (20). The invention also relates to a method for heating up extrusion dies prior to their installation in an extruder.

Abstract: The invention discloses a method for forming substantially striae-free glass substrates that are suitable for optical applications, including use in forming optical elements or structures such as mirrors and platen stage structures that can be used, for example, in EUV lithography. The method includes forming a mixture of silica soot, binder, lubricant and solvent. The homogenized mixture is then extruded through a slit die or mask into a flat planar pre-form, and the extruded pre-form is then consolidated by heating into a substantially full density, substantially striae-free lithography glass substrate structure. The consolidated perform has a substantially uniform coefficient of thermal expansion and is also substantially void free.

Abstract: Glass substrate comprising raised glass elements (20) placed over part of its area, characterized in that the glass elements (20) are intrinsically incorporated into the substrate. Advantageously, this substrate is used in a plasma screen for which the front face includes a first electrode array (13a, 13b) and the rear face, which consists of said structured substrate, includes a second electrode array (12) approximately perpendicular to the first array (13a, 13b) and placed on the external face (23) of the structured substrate, opposite the space (21) lying between the raised elements (20), while phosphors (16) occupy, surfacewise, the space (21) lying between the raised elements.

Abstract: A method and apparatus is described, with which individual rectangular glass panes of thickness between 0.03 mm and 2 mm can be cut from a glass band (2) drawn vertically from a hot forming device (1) in an in-line process with reduced rejects and reduced waste. The method provides that the glass band (2) drawn vertically downward through a vertical zone is cooled below a lower cooling point of the glass and subsequently is deflected through a bending zone (3b) with a bending radius between 0.1 m and 4 m into a horizontal zone (3c) in which it is horizontally oriented. The vertical alignment of the glass band (2) in the vertical zone (3a) is continuously monitored. At least one cutting process is performed on the horizontally oriented glass band (2) in the horizontal zone (3c). The device (20) for monitoring the vertical alignment of the glass band (2) includes at least three sensors (22a, 22b, 22c; 22a′, 22b′, 22c′) that detect the glass edges These sensors can be mechanical rollers.

Abstract: Silica grain of desired properties and size is created in a vacuum chamber. Fine silica powder is injected in the chamber or silica powder is formed in situ by combusting precursors. A plasma is formed centrally in the chamber to soften the silica powders so that they stick together and form larger grains of desired size. The grains are collected, doped, fused and flowed into tubes or rods. A puller pulls the tube or rod through a chamber seal into a lower connected vacuum chamber. The tube or rod is converted to rods and fibers or plates and bars in the connected chamber. Fused silica in a crucible tray is subjected to ultrasound or other oscillations for outgassing. Gases are removed by closely positioned vacuum ports.

Abstract: The present invention is concerned with a process for the formation of dental restorations from glass-ceramic materials and the resulting dental restorations. In this invention, a dental restoration is prepared by placing a glass-ceramic material in a heat-pressure deformable crucible. Heat is then applied to the crucible in order to bring the glass-ceramic material to a working range at temperatures above its liquidus temperature. The crucible in which the glass-ceramic material is placed has heat-pressure deformation properties which are matched to the working temperature of the glass-ceramic material being heated. The heat deformation properties of the crucible must be such that when the glass-ceramic material in the crucible is in the working range the crucible is heat-pressure deformable without rupturing.

Abstract: A method for molding optical glass elements including the steps of injecting molten glass material into a mold cavity through an injection port, runner and gate; cooling molten glass material in the mold cavity to a solidified state; and applying vibrations to solidified glass material in the mold cavity through a gate-forming member inserted into the mold assembly to form a gate to make a gate cut by concentration of stresses at boundary regions between the gate and the mold cavity.

Abstract: An apparatus (10) for extruding glass tubing (12) which comprises a furnace (14). A component (16) within the furnace (14) is for holding molten glass (18). A duplex mandrel (20) on one end of the furnace (14) is connected into the holding component (16). A facility (22) is for forcing the molten glass (18) in the holding component (16) out through the duplex mandrel (20), so as to form the glass tubing (12) having an upper support segment (24) and a lower structural segment (26). An assembly (28) is for quick cooling the upper support segment (24) of the glass tubing (12) upon exiting the duplex mandrel (20), so that the lower structural segment (26) will maintain its desired shape while slow cooling.

Abstract: A glass rod used as a molding material is inserted into a cylinder, pressed and heated with a temperature gradient in which the tip side of the glass rod is at a higher temperature. The glass rod is melted on the tip side thereof, and it is solidified on the rear side in the vicinity of the inlet of the cylinder, the solid portion functioning as a plunger when the rear side is pushed. When the glass rod is forwardly moved, the molten glass on the tip side is injected from an injection nozzle and is filled in the cavity of a forming mold. Since the glass rod itself is made of a molding material and functions as a plunger, when the tip side is melted and consumed, the solid portion on the rear side is forwardly moved and melted. It is thus possible to perform continuous mold forming without complicating the mechanism and steps and to improve the quality of the molded product.

Abstract: A method for manufacturing a preform having steps of obtaining a plastic material by kneading silica powder, a binder, water, and a surfactant, and obtaining a porous preform by extrusion-molding the plastic material.

Abstract: A glass preform for an optical fiber containing a dopant in a core portion at a high concentration is produced by providing a glass tube, forming a coating film of a sol-gel solution containing a dopant compound on an inner wall of the glass tube, vitrifying and collapsing the glass tube having the coating of the sol-gel solution to obtain a glass rod.

Abstract: For the production of a composite glass powder of any particle size from a fine particle size, multi-component mixture of a low-melting glass powder, fillers, and additives, the fine particle size, multicomponent mixture is sintered for 10-60 minutes at a temperature at which the base glass has a viscosity of 10.sup.5 to 10.sup.6.5 dPas, and the resultant sintered cake is ground to a powder of the desired particle size. If the multicomponent mixture comprises components decomposable with the release of gas, e.g., copper carbonate, the latter are decomposed prior to sintering at a temperature below the sintering temperature. The resultant composite glass powder containing copper oxide can be used for coating varistors.

Abstract: The invention relates to high-porosity silica xerogels and a process for their preparation consisting of subjecting silica alcogels to thermal treatment in the presence of organic compounds containing amino and hydroxyl groups.The xerogels are characterised by a total pore volume .gtoreq.2 cc/g and a mean pore diameter .gtoreq.100 .ANG..

Abstract: A method of manufacturing distributed index optical elements is disclosed. The method comprises a step of preparing silica sol including at least one of metal dopants, a step of dipping, after subjecting the silica sol to a gelling treatment, the silica gel in an elute into which a part of metal constituents other than silicon including in the gel is selectively eluted, and a step of drying and sintering the silica gel.

Abstract: The method of manufacturing a silica glass preform comprises the steps of inserting a rod-like member mainly containing a ductile material, into a forming space of a mold, charging the remaining space of the forming space with a forming material containing silica glass powder or doped silica glass powder, compressing the mold charged with the forming material from outside such as to form a porous glass body of the forming material around the rod-like member, removing the rod-like member from the porous glass body, inserting a glass rod into the hole formed after removal of the rod-like member, purifying said porous glass body in which the glass rod is inserted, and consolidating said porous glass body purified in the above purifying step.

Abstract: In order to prepare particles of a vitreous enamel for use in forming a vitreous enamel body by fusing the particles together to form the body, at least one enamel frit and at least one non-vitreous additive are formed into an agglomerated granular feedstock and passed through a heating chamber whereby such feedstock becomes at least partially molten and rounded, whereafter the resulting rounded vitreous enamel beads are caused or allowed to cool to a temperature below their melting point.

Abstract: A process for the preparation of monoliths of aerogels of metal oxides, which aerogel is either constituted by one single oxide, or is constituted by a mixture of oxides, is disclosed, which process consists of the following operating steps:(a) the relevant metal alkoxide(s) is/are mixed with water in the presence of a catalyst of acidic character;(b) the so obtained mixture is hydrolysed;(c) a colloidal suspension of the oxide of a metal equal to, or different from, the metal(s) used in the (a) step is added to the hydrolysate;(d) the so obtained colloidal solution is caused to turn into a gel (gelation) having the desired shape and dimensions;(e) the gel is washed;(f) the gel is dried at values of temperature and pressure which are higher than the critical pressure and temperature values of the solvent used for the washing.

Abstract: Method of manufacturing tubes in which a mixture of powdered tube material and a liquid binder is introduced into a tubular mold with a geometry corresponding to the geometry of the tube to be formed. The tubular mold is rotated about its longitudinal axis. The powder-binder mixture deposits on the inner wall of the tubular mold. The powder and the liquid are introduced into the tubular mold separately.

Abstract: In production of a closed package-type semiconductor assembly provided with a built-in semiconductor element and conductive leads for connection to outside devices, a conductive island, the conductive leads and other accessories are united together by one stage moulding of molten glass. Simple process reduces the production cost greatly and no use of dusty ceramic components much raises functional reliability of the product.

Abstract: Disclosed is a method of producing thin films by sintering which comprises:a. coating a substrate with a thin film of an inorganic glass forming parulate material possessing the capability of being sintered, andb. irridiating said thin film of said particulate material with a laser beam of sufficient power to cause sintering of said material below the temperature of liquidus thereof.Also disclosed is the article produced by the method claimed.

Abstract: A method of fabricating rare earth doped planar optical waveguides for integrated optical circuits includes introducing a first carrier gas to a heated column of rare earth chelate to create a flow of rare earth chelate vapor in the carrier; introducing a second carrier gas through a silicon precursor to create a flow of silicon precursor vapor in the carrier; submitting the flow of rare earth chelate vapor and the flow of silicon precursor vapor with oxygen and a homogenizing agent to a flame hydrolysis deposition burner to produce a soot of rare earth doped silica; and depositing the soot on a planar substrate; and etching the soot, after consolidation, to define one or more discrete channel waveguides.

Abstract: A method is disclosed for preparing an improved bioreactive material of the glass or partially crystallized glass type for bone prostheses or dental implants, which can be welded to bone tissue by chemical bonding. The material consisting essentially of, by weight, 5 to 14% Na.sub.2 O, 0 to 12% P.sub.2 O.sub.5, 49 to 57% SiO.sub.2, and balance, no more than 33% CaO+CaF.sub.2, the material containing 0.5 to 7% CaF.sub.2, and is prepared by a method comprising the steps of preparing a mixture of powders constituting a precursor of the material made of carbonates, phosphates, silica, oxides and fluorides, melting, homogenizing, casting and cooling the mixture to obtain an intermediate, non-crystallized glass, optionally annealing, and then grinding, either pressing the non-crystallized ground glass obtained cold to shape it, then sintering naturally or under a load after degassing, or sintering under a load directly after degassing, then cooling and optionally polishing or machining.

Abstract: A composite substrate is fabricated by applying to a glass fiber substrate a liquid sol-gel composition and then sintering the sol-gel to convert it to the glass phase. A polymeric coating is then applied.

Abstract: A composite article, such as a telescope mirror blank, comprising a solid glass body and a supporting network structure, the structure being composed of a network of interlocking struts frit sealed to one another and to the face plate. The article is characterized in that sufficient of the glass body is incorporated in particulate form in the struts to maintain an average expansion mismatch (-50.degree. C. to +50.degree. C.) between the network structure and the glass body of no more than 0.15 ppm/.degree.C.

Abstract: A process for producing a ceramic preform, which comprises mixing an alkoxysilane and fine silica powder, molding the mixture, followed by heating for de-alcoholysis.

Abstract: A method for foming glass articles of substantial thickness from unstable glass compositions which normally devitrify when formed by conventional casting or molding processes, is disclosed. The method includes the steps of quench-cooling the glass to form a crystal-free glass feedstock material, and then pressure-consolidating the feedstock at a temperature between the transition temperature and the crystallization temperature of the glass.

Abstract: In order to eliminate the effect of water attack on silica optical fibres, the fibres are provided with a surface layer of silicon nitride or silicon oxynitride. The method proposed includes direct nitridation. This may be achieved by adding a nitriding atmosphere to the drawing furnace gases, or to the reactive gases (TiCl.sub.4 and SiCl.sub.4) incorporated in the flame of an oxyhydrogen torch for the formation of a compressive silica/titania layer on an optical fibre by a glass soot deposition and sintering process.

Abstract: A method of producing glass bodies having regions with different optical refraction, including a basic body and a coating layer which is sintered onto the basic body, covers the basic body at least partially and is made of glass, which as it is doped, has an index of refraction differing from that of the glass of the basic body. The starting material for producing the cladding on the basis of pulverulent ceramic material is deformed into a self-supporting, unsintered porous green body, is dried and submitted to a cleaning procedure in a heated gas phase. The coating layer to be bonded onto the basic body is melted into glass in a subsequent combined doping/sintering procedure in a gas phase containing the doping agent at a temperature in the range from 1150.degree. to 1500.degree. C. and is sintered onto the basic body.

Abstract: A method of manufacturing a large-diameter gradient-index glass having a predetermined refractive index gradient includes the steps of (a) hydrolyzing a solution consisting of an alkoxide of silicon and an alkoxide of boron to prepare a sol, (b) adding an aqueous solution of lead acetate and an organic acid to the sol to prepare a gel porous body, (c) aging and sequentially treating the gel porous body by using a water-isopropanol solution of lead acetate, an isopropanol-acetone solution, and acentone, thereby performing a pretreatment, (d) dipping the pretreated gel porous body into a lower alcohol solution of at least one of potassium acetate and sodium acetate to form a lead ion concentration distribution which is gradually changed from a surface to an interior of the gel porous body, (e) sequentially treating the gel porous body having the lead ion concentration distribution by sequentially using an isopropanol-acetone solution and acentone, and (f) drying and heating the gel porous body to prepare a glas

Abstract: Silica glass powders are prepared by mixing a silicic acid ester, water in an amount equal and or larger than 0.5 gram equivalent of an alkoxy group of the silicic acid ester and siliceous particles and dispersing the siliceous particles which have particle sizes larger than 400 .mu.m in an amount of less than 10% by weight and particle sizes of less than 20 .mu.m in an amount of less than 50% by weight and which are dispersed in an amount equal to or larger than 10% by weight of the weight of silica prepared by roasting the silicic acid ester in the same amount as used for the preparation of the mixture, gelling the dispersion to give a gel, drying the gel, and sintering the dried gel. The silica glass powders of high purity are suitable for various uses such as raw materials for the silica glass products for semiconductor industry and for multicomponent glass for optical communication.

Abstract: A process for producing porous glass, which comprises preparing a reaction solution containing a metal alkoxide or its oligomer and an organic polymer, hydrolyzing and polymerizing the metal alkoxide or its oligomer in the solution to obtain a gel, and calcining the gel to obtain porous glass, wherein the organic polymer has compatibility with the solution of the metal alkoxide or its oligomer, undergoes phase separation during the hydrolysis-polymerization step and is substantially free from formation of precipitates.

Abstract: A method is disclosed for recycling reinforced plastic composite materials. The reinforced plastic composite material is heated to separate said plastic matrix material from said reinforcement material. At least the separated reinforcement material is recycled. The products produced by these methods and processes are also disclosed.

Abstract: A heating furnace for heating a porous preform made of fine particles of quartz base glass for an optical fiber in an atmosphere comprising a fluorine-containing atmosphere to add fluorine to the preform and to vitrify the preform to produce a glass preform for an optical fiber, which comprises a heater and a muffle tube positioned inside the heater to separate a heating atmosphere from the heater, wherein at least the inner layer of the muffle tube consists of highly pure carbon.

Abstract: A method for consolidating a green body is disclosed which involves: (1) drying and partially sintering the green body at a temperature above about 1000.degree. C. and in an atmosphere containing chlorine; (2) fully sintering the green body under vacuum at a temperature above about 1720.degree. C.; and (3) hot isostatic pressing ("hipping") the green body at a temperature above about 1150.degree. C. and at a pressure above about 100 psig. The process produces glass articles which have a low water content and are essentially bubble free.This is a continuation of co-pending application Ser. No. 07/271,709 filed Nov. 16, 1988, now abandoned which is a divisional application of application Ser. No. 07/052,619, filed May 20, 1987 now U.S. Pat. No. 4,789,389.

Abstract: Disclosed is the manufacture of a stress-free composite including reinforcing fibers embedded in and bonded to a matrix material such that differential contraction takes place in the matrix material relative to the fibers in response to temperature decrease. It involves embedding the fibers in the matrix material at an embedding temperature to obtain a composite precursor preparatory to subsequent consolidation thereof into the composite material at a consolidation temperature, and longitudinally stretching the fibers to such an extent that the longitudinal dimension of any portion of each fiber is substantially the same as that of the contiguous portion of the matrix material both at the consolidation temperature with the fiber stretched and at a predetermined operating temperature of the composite material in the absence of such stretching.

Abstract: The present invention relates to producing a polymeric alkali metal silicate glass powder by repeated steps of partial hydration and dehydration until the desired degree of polymerization has taken place. The polymeric alkali metal silicate glass may be utilized to produce aqueous polymeric alkali metal silicate glass solutions containing a suspension. This solution containing a suspension may be used as an adhesive, a binding agent, a laminating agent, coating agent and molding material.

Abstract: Filter bodies are made by mixing borosilicate glass powder, potassium sulphate and 30% aqueous polyethylene glycol solution per kilogram of mixture. The mixture is filtered and dried and glass particles of a different size are mixed into the dried granulate. The resulting mixture is compressed at a pressure of 1000 bar to form blanks and sintered at about 860.degree. C. After cooling, the potassium sulphate is washed out of the blanks.

Abstract: A telescope mirror blank having a supporting network core composed of sintered ceramic struts, and a method of forming such core from a thermally crystallizable, powdered glass and as a separate component from the faceplate, are disclosed. Optionally, the mirror faceplate may be formed in a similar manner.

Abstract: In order to eliminate the effect of water attack on silica optical fibres, the fibres are provided with a surface layer of silicon nitride or silicon oxynitride. The method proposed comprises direct nitridation. This may be achieved by adding a nitriding atmosphere to the drawing furnace gases, or to the reactive gases (TiCl.sub.4 and SiCl.sub.4) incorporated in the flame of an oxyhydrogen torch for the formation of a compressive silica/titania layer on an optical fibre by a glass soot deposition and sintering process.

Abstract: Alkali metal silicate glass is mixed with water to form an aqueous alkali metal silicate glass suspension, then dried to form a flexible solid alkali metal silicate glass product which may be heated to above the boiling temperature of water to produce a cellular product. The flexible solid product may be utilized as a flexible film, as an adhesive, a coating agent and a binding agent. The foamed product may be used for thermal and sound insulation.

Abstract: A method for consolidating a porous glass preform is provided in which a preform is placed in a stationary elongated chamber and selected portions of the chamber, distributed along the chamber's length, are sequentially heated above the preform's sintering temperature. In certain preferred embodiments, the chamber is surrounded by an elongated susceptor and the heating is performed by moving an induction heating coil along a path parallel to the longitudinal axes of the susceptor and the chamber.

Abstract: A heating oven is provided for processing glass materials, e.g., porous glass preforms, from which optical waveguide fibers are prepared. The oven includes a stationary elongated chamber, e.g., a silica muffle, for receiving the glass material which is to be processed. At least a portion of the chamber is surrounded by a stationary susceptor. The chamber is heated by moving an energized induction heating coil along a path parallel to the longitudinal axes of the susceptor and the chamber.

Abstract: A process for manufacturing open porous sintered bodies with large open pore volume and defined pore diameters and which at least predominantly consist of glass-ceramics. They are obtained by sintering a mixture of sinterable powder and an inorganic soluble salt with defined grade of grain, the melting point of which is above the densification temperature of the sinterable powder. For the formation of a molded body the mixture of sinterable powder and inorganic salt is submitted to a molding process. The molded body is sintered in a sintering process and the soluble salt being contained in the molded body is lixiviated. As a main constituent the sinterable powder contains a pulverized crystallizable glass powder.

Abstract: In a method of vacuum refining molten glass or the like, selenium is provided in the molten glass to serve as a foaming agent, which yields improved refining. Alternatively, colored glass compositions that include selenium as a colorant are refined at higher than normal pressures to retain selenium in the glass without sacrificing refining performance.

Abstract: Method of and arrangement for manufacturing rotationally symmetrical porous solid bodies.A method of manufacturing rotationally symmetrical porous solid bodies, in which the starting material for the solid body in the form of a suspension consisting of the material for the solid body in solid form and a liquid dispersing agent, is introduced into a hollow mould whose geometry corresponds to that of the solid body to be formed, such that during the introduction of the suspension the hollow mould is rotated about its longitudinal axis, a certain quantity of solid of the suspension being deposited on the inner wall of the hollow mould, and excess residual suspension being removed, after which the green body thus formed is subjected to further process steps to manufacture the solid body, in which process suspension is introduced into the hollow mould in such doses that each time only thin solid layers having a thickness in the range from 10.sup.