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EP1242324A1 - Silice pure fondue, four et procede correspondants - Google Patents

Silice pure fondue, four et procede correspondants

Info

Publication number
EP1242324A1
EP1242324A1 EP00961725A EP00961725A EP1242324A1 EP 1242324 A1 EP1242324 A1 EP 1242324A1 EP 00961725 A EP00961725 A EP 00961725A EP 00961725 A EP00961725 A EP 00961725A EP 1242324 A1 EP1242324 A1 EP 1242324A1
Authority
EP
European Patent Office
Prior art keywords
aluminum dioxide
fused silica
refractory
crown
silica glass
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00961725A
Other languages
German (de)
English (en)
Inventor
Lawrence H. Kotacska
Robert S. Pavlik, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Corning Inc
Original Assignee
Corning Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corning Inc filed Critical Corning Inc
Publication of EP1242324A1 publication Critical patent/EP1242324A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B20/00—Processes specially adapted for the production of quartz or fused silica articles, not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
    • C03B19/1407—Deposition reactors therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B17/00—Furnaces of a kind not covered by any of groups F27B1/00 - F27B15/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/0033—Charging; Discharging; Manipulation of charge charging of particulate material
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/02—Pure silica glass, e.g. pure fused quartz
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/02—Pure silica glass, e.g. pure fused quartz
    • C03B2201/03—Impurity concentration specified
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/07—Impurity concentration specified
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/40—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
    • C03B2201/42—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn doped with titanium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/30—For glass precursor of non-standard type, e.g. solid SiH3F
    • C03B2207/32—Non-halide
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/50—Multiple burner arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path
    • F27B9/26—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path on or in trucks, sleds, or containers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0043—Floors, hearths

Definitions

  • An article of relatively pure fused silica and a furnace and method for producing the article.
  • Relatively pure metal oxides are produced by thermal decomposition of precursors and deposition of the resulting oxides.
  • the precursor may take the form of a vapor, or may be carried by a vapor. It may be decomposed by either flame hydrolysis or pyrolysis.
  • One such process is production of fused silica by hydrolysis or pyrolysis of silicon tetrachloride.
  • Early patents disclosing such processes for producing silica are United States Patent No. 2,239,551 (Nordberg) and 2,272,342 (Hyde).
  • a commercial application of flame hydrolysis involves forming and depositing particles of fused silica to form large bodies (boules). Such boules may be used individually, or may be finished and integrated together into large optical bodies, such as telescope mirrors.
  • SiCl is hydrolyzed, and the hydrolyzed vapor is passed into a flame to form molten particles of fused silica.
  • the particles are continuously deposited on a bait, or in a crucible, known as a cup, to form a boule.
  • the invention includes a method of making a fused silica glass.
  • the method includes providing a silica feedstock, and providing a furnace crown and cup consisting essentially of aluminum dioxide, with the crown covering a consolidating non-porous fused silica glass mass.
  • the method further includes delivering the silica feedstock to reaction site burners mounted within the aluminum dioxide crown wherein the silica feedstock is converted into silica particles which are deposited and consolidated into the fused silica glass mass.
  • the invention further includes a fused silica glass furnace for converting a non- silica fluid silica precursor feedstock into a fused silica glass, the fused silica glass furnace having a contained furnace interior.
  • the contained furnace interior has a maximum furnace operation temperature MFOT.
  • the furnace interior is comprised of a conversion deposition consolidation site where the precursor feedstock is converted into silica soot and the converted silica soot is then deposited and consolidated into a fused silica glass.
  • the furnace interior is contained and insulated by aluminum dioxide refractory bricks with the aluminum dioxide refractory bricks having a fired temperature FT, where FT > 1650°C, and the aluminum dioxide refractory bricks consist essentially of Al and O.
  • An embodiment of the present invention resides in an improved method of producing a fused silica body by introducing a silicon-containing compound into a flame to form molten silica particles and collecting those particles in the form of a fused silica body in a furnace constructed of refractory materials, the improvement comprising constructing at least a portion of the furnace from refractory materials that have been exposed to a reactive, halogen-containing gas to react with and thereby cleanse the refractory of contaminating metals.
  • a further aspect of the invention resides in a relatively pure fused silica material in which the fused silica has a transmittance value of at least 99.5% for 248 nm radiation, a transmittance value of at least 98% for 193 nm radiation, at least a substantial portion of the body has an acceptable fluorescence level when exposed to such radiation, and the fused silica material has a content of contaminating metal ions less than 100 ppb.
  • the invention further resides in a refractory furnace for collecting molten silica particles in the form of a solid body, at least a portion of the furnace being constructed of a refractory that contains mobile metal contaminants in an amount less than 300 ppm.
  • FIG. 1 is a schematic representation of an apparatus and process for making fused silica glass in accordance with the invention.
  • FIG. 2 is a top view of a fused silica glass furnace refractory arched dome crown in accordance with the invention.
  • FIG. 3 is a cross-section view of the arched dome crown in accordance with the invention.
  • FIG. 4 is a cross-sectional view of a fused silica glass furnace cup in accordance with the invention.
  • FIG. 5 illustrates a carbo-chlorination cleansing furnace and treatment process in accordance with the invention.
  • the conventional boule process used in making fused silica is a one-step process.
  • a carrier gas is bubbled through a SiCl 4 feedstock that is maintained at a specified low temperature.
  • the vaporous SiCl 4 is entrained in the carrier gas and is thereby transported to the reaction site.
  • the reaction site is comprised of a number of burners that combust and oxidize the vaporous SiCl 4 to deposit silica at a temperature greater than 1600°C.
  • the apparatus and transfer system be capable of vaporizing the feedstock and delivering the vaporized feedstock to a burner in the vapor state.
  • the apparatus and process may remain substantially unchanged with one major exception.
  • the SiCl 4 feedstock is replaced by a polymethylsiloxane.
  • Use of this substitute feedstock may require some minor adjustments, such as a somewhat higher delivery temperature (e.g., 100-150°C). This is due to the siloxane having a somewhat lower vapor pressure than SiCl .
  • FIG. 1 in the accompanying drawing is a schematic representation of an apparatus and process for producing and depositing molten silica particles to build up a large, fused silica boule.
  • the apparatus generally designated by the numeral 10, includes a feedstock source 12. Nitrogen, or a nitrogen/oxygen mixture, is used as the carrier gas. A bypass stream of nitrogen 14 is introduced to prevent saturation of the vaporous stream. The vaporous reactant is passed through a distribution mechanism to the reaction site wherein a number of burners 18 are present in close proximity to a furnace crown 20. The reactant is combined with a fuel/oxygen mixture 22 at these burners, and is combusted and oxidized to deposit silica at a temperature greater than 1600°C.
  • High purity metal oxide soot and heat are directed downwardly through the refractory furnace crown 20.
  • the silica is immediately deposited and consolidated to a non-porous mass 24 on hot cup 26.
  • Improvement in the zircon refractory alleviated the affect of sodium ion contamination in a fused silica article.
  • other contaminants also exist in the furnace refractory in addition to sodium. These include the alkaline earth metals, and transition metals, such as iron, and lead, phosphorous, sulfur, other alkali, and aluminum, and particularly mobile metal contaminants which degrade UV optical transmission of the glass.
  • Contaminating metals can be present in the raw materials employed in production of furnace refractories.
  • the metals may also be entrained during sintering of the refractory, or during any subsequent operations, such as sawing or grinding.
  • this degree of contaminating metal control in a collection furnace can be achieved by constructing the furnace of refractory materials containing less than 300 parts per million (ppm) of the contaminating metals.
  • ppm parts per million
  • zircon refractories used in a collection furnace for fused silica deposition This desirable end is accomplished, in accordance with the present invention, by firing the furnace refractories in a halogen-containing atmosphere.
  • the halogen reacts with and removes the contaminating metals from at least the exposed surface of the refractory.
  • chlorine or fluorine, alone or in acid gas form to be especially useful.
  • the cleansing gas can be used in essentially pure form.
  • the cleansing treatment may employ a continuous flow of the halogen gas.
  • a pulsed type treatment may be used wherein gas is repeatedly introduced into the firing cleaning chamber and subsequently exhausted.
  • the cleansing action can occur at a temperature as low as 700°C. However, it is usually preferred to employ somewhat higher temperatures in the range of 1100 to 1500°C.
  • the invention is here described with reference to treatment of refractory furnace elements.
  • the cleansing process on a refractory body is preferably carried out prior to assembly into a furnace.
  • the treatment may be carried out during the production of the refractory prior to assembly into a furnace.
  • the cleaner deposition furnace provides a fused silica product of high purity. It provides high, consistent yields of fused silica glass having an acceptably high transmission of short wavelength UV radiation and a low level of fluorescence. Further, the glass is less prone to increases in radiation damage and fluorescence in service. These desired ends are achieved without requiring change in, or compromise of, either the furnace design or the silica forming and deposition process. This is highly significant because these features are critical to achievement of refractive index homogeneity in the glass. The effectiveness of the cleansing treatment was demonstrated by comparing two sets of fused silica test pieces made with zircon refractories.
  • One set was taken from boules deposited in an untreated collection furnace made of zircon refractories.
  • a second set was taken from boules deposited in a treated furnace made of treated zircon refractories.
  • the furnaces were constructed in essentially identical design with sintered zircon refractory crowns and cup liners.
  • the zircon refractories in the treated furnace were soaked for eight hours in a cleansing furnace operating at 1300°C. A flowing atmosphere of 5.7% Cl and 94.3% helium was maintained during the entire time.
  • TABLE I shows internal transmittance in percent as determined on the basis of measurements for both 248 nm and 193 nm wavelength radiation.
  • the fused silica boules described above were also analyzed to determine the percentage of boule depth that exhibited an acceptable low level of fluorescence. Fluorescence is determined by integrating the intensities measured over the range of 400-700 nm. To be acceptable, a glass test piece must exhibit a value, as so determined, that is below 4.2x10 "9 watts/cm 2 when the glass is exposed to an emitting laser operating at 15 mJ/cnr and 200 Hz. Glass from the untreated furnace was completely unacceptable. There was no portion of the boule in which the fluorescence value was acceptably low. Glass from the treated furnace had acceptable glass to a depth of 3.53 inches. This represented 59.3% of the total depth.
  • the invention includes a method of producing a fused silica body by introducing a silicon-containing compound into a flame to form molten silica particles and collecting those particles in the form of a fused silica body in a furnace constructed of alumina refractory materials.
  • the improvement includes collecting the silica particles in a furnace at least a portion of which has been exposed to a reactive, halogen-containing gas to react with, and thereby cleanse the refractory of contaminating metals.
  • the invention includes a method of making a fused silica glass.
  • the method includes providing a silica feedstock, providing a furnace crown consisting essentially of aluminum dioxide with the crown covering a consolidating non-porous fused silica glass mass.
  • the method includes delivering the silica feedstock to multiple reaction site burners mounted in the aluminum dioxide crown wherein the silica feedstock is converted into silica particles which are deposited and consolidated into the fused silica glass mass.
  • FIG. 1-5 illustrate the inventive method of making a high purity fused silica glass.
  • a silica feedstock is provided from a feedstock source 12.
  • the silica feedstock is delivered to burners 18 in a fluid vaporous state.
  • the silica feedstock vapor is produced with a feedstock vaporizer with the vapors preferably delivered through conduits with the assistance of carrier gases such as nitrogen and oxygen.
  • the method includes providing a furnace crown 20 which consists essentially of aluminum dioxide.
  • the provided aluminum dioxide crown 20 covers a consolidating hot non-porous fused silica glass mass 24.
  • the silica feedstock is delivered to multiple reaction site burners 18 which are mounted in the provided aluminum dioxide crown 20.
  • the delivered feedstock is converted by the reaction flame/heat of the burners into fine silica soot particles 30 which are deposited on and consolidated into fused silica glass mass 24.
  • the method preferably includes providing a cup 26 for containing and contacting silica glass 24 inside the furnace.
  • furnace cup 26 consists essentially of aluminum dioxide.
  • the provided silica feedstock is a high purity silica feedstock with a contaminating metal ion content less than 100 ppb and the consolidated fused silica glass mass has a contaminating metal ion content less than 100 ppb.
  • the silica feedstock is a halide-free silica feedstock, most preferably a siloxane.
  • the silica feedstock is a halide containing feedstock which preferably is SiCl 4 .
  • providing the silica feedstock includes providing a titanium dopant source and the fused silica glass mass is comprised of a titanium doped fused silica.
  • Providing aluminum dioxide crown 20 preferably includes providing non-Cl- treated aluminum dioxide refractory blocks 32 and exposing the non-Cl-treated aluminum dioxide refractory blocks 32 to a reactive halogen-containing gas 33. As shown in FIG. 5, refractory blocks 32 are treated with a reactive halogen-containing gas cleansing treatment to provide halogen treated cleansed refractory block members 34. The method preferably includes assembling halogen treated cleansed aluminum dioxide refractory blocks 34 to provide crown 20 consisting essentially of aluminum dioxide.
  • providing aluminum dioxide cup 26 includes providing non-Cl-treated aluminum dioxide refractory members 32 and exposing the non-treated refractory members to the reactive halogen-containing gas 33 to provide halogen treated cleansed aluminum dioxide refractory members 34 which are then assembled to form cup 26 such as shown in FIG. 4, which consists essentially of aluminum dioxide.
  • untreated aluminum dioxide refractory members 32 are provided by shaping and machining aluminum dioxide refractory preforms.
  • the preforms are preferably formed/shaped into predetermined shapes and sizes that allow for their assembly into furnace crown 20 and cup 26.
  • the preforms are machined into refractory members 32 with cutting saws and drills, and in an embodiment the aluminum dioxide refractories are wet machined.
  • Such machining/shaping of the refractory members 32 is preferably performed prior to reactive halogen -containing gas cleansing treating most preferably with the cleansing treatment being the final manufacturing making process prior to assembly of cleansed brick members 34 into furnace cup 26 and crown 20.
  • the preferred reactive halogen- containing gas cleansing treatment of the invention comprises carbo-chlorination purifying the refractory brick block members. As shown in FIG. 5, the refractory furnace members are treated in a carbo-chlorination treatment furnace 36.
  • the carbo- chlorination treatment furnace 36 preferably is a graphite containment vessel 38 that has at least one vacuum/gas treatment inlet/outlet 40 that allows for a vacuum to be pulled within the sealed vessel 38 and allows for the controlled input and output of treatment gases such as chlorine, helium and hydrogen and mixtures thereof.
  • the graphite treatment furnace vessel includes a particulate/powder carbon bed 42, such as a graphite carbon black powder so that an appropriate level of carbon is present in the furnace for carbo-chlorination of the refractory members.
  • Treatment furnace 36 includes an appropriate heating source such as inductive heating elements or electrical resistive heating elements so that the interior and contents of vessel 38 can be heated to an elevated reaction temperature in the range of 1000 to 1500°C and preferably at least 1200°C to carbo-chlorinate the contents.
  • an appropriate heating source such as inductive heating elements or electrical resistive heating elements so that the interior and contents of vessel 38 can be heated to an elevated reaction temperature in the range of 1000 to 1500°C and preferably at least 1200°C to carbo-chlorinate the contents.
  • impurities are also treated and reacted with the carbon in the furnace preferably with the carbon reducing metal contaminants in the refractories.
  • a preferred carbo-chlorination cleaning treatment includes loading the refractory members into the treatment furnace along with the carbon bed.
  • the furnace temperature is elevated to the preferred reaction temperature range of 1000 to 1500°C (preferably at least 1200°C) while a vacuum is pulled and maintained for a time that allows appropriate carbon reaction with oxides present, then a chlorine treatment gas is repeatedly fed into the vessel, preferably chlorine gas treatment exposures of about 30 to 60 minutes between chlorine feed in shots, preferably with 2 to 5 of the 30 to 60 minute exposures done at the elevated reaction temperature.
  • the preferred chlorine gas treatment atmosphere is comprised of 2.5 to 20% Cl 2 , more preferably 3 to 10% Cl 2 , more preferably 4 to 8% Cl 2 , and most preferably about 6% ⁇ 1% Cl 2 , with the balance net of the treatment atmosphere helium. After such chlorine feed in shots a vacuum is pulled again while maintaining the temperature.
  • this carbo-chlorination treatment of vacuum- chlorine-vacuum is repeated at least one more time to ensure proper carbo-chlorination cleansing of the refractory members.
  • the treatment vessel and contents is preferably swept with a sweeping treatment gas such as helium or hydrogen.
  • a sweeping treatment gas such as helium or hydrogen.
  • Preferred refractory members are provided by at least two carbo- chlorination treatments.
  • the carbo-chlorinated refractory brick members of the invention provide high purity fused silica with UV transmission at KrF 248nm of at least 99.9%/cm and at least 99.3%/cm at ArF 193nm and achieves high purity fused silica with 99.7%+/cm at 193nm.
  • the invention includes providing furnace cup 26 consisting essentially of aluminum dioxide and containing the consolidating non-porous fused silica glass mass 24 in the aluminum dioxide cup.
  • furnace cup 26 consisting essentially of aluminum dioxide and containing the consolidating non-porous fused silica glass mass 24 in the aluminum dioxide cup.
  • the aluminum dioxide crown and cup refractory members 34 are un- coated aluminum dioxide.
  • the aluminum dioxide crown and cup refractory members 34 are a silica free aluminum dioxide which are essentially free of Si and SiO .
  • the aluminum dioxide has a SiO 2 level less than 2000 ppm by weight.
  • Preferably providing the aluminum dioxide crown and cup refractory members 34 includes providing an unfired aluminum dioxide refractory precursor and firing the aluminum dioxide refractory precursor at a temperature of at least 1660°C to provide a fired aluminum dioxide refractory member 34 and assembling the fired aluminum dioxide refractory member 34 to form and provide the furnace crown and cup.
  • the aluminum dioxide refractory precursor is fired at a firing temperature of at least 1665°C, more preferably at least 1670°C, and most preferably at least 1675°C.
  • providing the aluminum dioxide crown preferably includes providing a plurality of porous aluminum dioxide refractory blocks and assembling the blocks into the crown, preferably having a porousity in the range of 25- 70%.
  • the aluminum dioxide crown 20 includes providing a plurality of aluminum dioxide refractory blocks 34 and assembling the blocks together to form an arched self-supporting dome crown.
  • the aluminum dioxide crown 20 is comprised of aluminum dioxide refractory members 34 with a bulk density ⁇ 3.9 grams/cm 3 , more preferably ⁇ 3 grams/cm 3 , more preferably ⁇ 2.5 grams/cm , more preferably ⁇ 2 grams/cm and ⁇ 1.4 grams/cm .
  • the aluminum dioxide refractory bulk density is preferably > 1.2 grams/cm 3 , with the range being about 1.2 to 3.8.
  • Preferably providing the aluminum dioxide crown 20 includes providing an aluminum dioxide refractory with a Young's Modulus of at least 2 X 10 6 psi. in the temperature range of 20°C to 1200°C.
  • Preferably providing the aluminum dioxide crown 20 includes providing an aluminum dioxide refractory 34 with a creep percentage under a 25 psi load at 1600°C for 150 hours of ⁇ 5% creep, more preferably a creep percentage under a 25 psi load at 1600°C for 150 hours of ⁇ 2 % creep, and most preferably a creep percentage under a 25 psi load at 1600°C for 150 hours of ⁇ 1.2 % creep.
  • the aluminum dioxide crown 20 has an emissivity ⁇ .35 at a temperature of 1100°C.
  • the invention preferably includes avoiding deposition of the silica particles 30 on the crown 20. Depositing/coating of silica particles on the aluminum dioxide crown is avoided and inhibited, preferably by controlling the direction in which the soot stream of the burners 18 are focused and ensuring they are fixed in the crown.
  • the invention further includes terminating the delivery of silica feedstock to the burners 18, cooling the fused silica glass mass 24, disassembling the aluminum dioxide crown 20, and disposing of the disassembled aluminum dioxide crown blocks 34 which have a service temperature greater than 1300°C.
  • the invention further includes a fused silica glass furnace for converting a non- silica fluid silica precursor feedstock into a fused silica glass.
  • the fused silica glass furnace 50 having a contained furnace interior 52, having a maximum furnace operation temperature MFOT, the furnace interior 52 including a conversion deposition consolidation site where the precursor feedstock is converted into silica soot, the converted silica soot then deposited and consolidated into a fused silica glass.
  • the furnace interior site 52 contained and insulated by a plurality of aluminum dioxide refractory bricks 34, the aluminum dioxide refractory bricks 34 having a fired temperature FT, with FT > 1650°C, and the aluminum dioxide refractory bricks consisting essentially of Al and O.
  • the aluminum dioxide refractory bricks 34 have a fired temperature FT with FT > MFOT + 20°C.
  • the aluminum dioxide refractory bricks 34 have a SiO level less than 2000 ppm by weight.
  • the aluminum dioxide refractory bricks 34 have a contaminating metal ion concentration less than 300 ppm, most preferably wherein the aluminum dioxide refractory bricks are Cl-treated cleansed carbo-chlorinated aluminum dioxide refractory bricks.
  • the aluminum dioxide refractory bricks have a Na concentration ⁇ 100 ppm by weight, a K concentration ⁇ 20 ppm by weight, a Fe concentration ⁇ 250 ppm by weight (preferably Fe ⁇ 150 ppm), preferably the aluminum dioxide refractory bricks 34 are micro-crack- free refractory bricks.
  • the aluminum dioxide crown bricks 34 are assembled together to form a self-supporting arched dome covering the furnace interior 52.
  • the aluminum dioxide cup bricks 34 are assembled together to form a cup container which contains the deposited consolidated fused silica glass, preferably with the glass in a flowing state inside the cup which is rotating.
  • the invention includes a fused silica glass furnace 50.
  • the fumace 50 includes a self supporting arched dome crown 20, such as shown in FIG. 2 and the cross-section thereof in FIG. 3.
  • the arched dome crown 20 is preferably comprised of interlocking aluminum dioxide refractory bricks 34.
  • the refractory bricks 34 consists essentially of Al and O.
  • the refractory bricks 34 have a bulk density in the range of 1.2 grams/cm 3 to 3 grams/cm 3 . As shown in FIG.
  • crown 20 has a plurality of burner holes 18 and a retaining ring 120 such as a steel metal ring structure for encircling crown 20 and maintaining the placement of bricks 34 in the arched dome structure during assembly/preparation of the furnace and while the crown rests on the foundation side walls of the furnace during furnace operation.
  • the aluminum dioxide refractory bricks have a fired temperature greater than 1650°C.
  • the refractory bricks 34 have a silica content less than 2000 ppm by weight, a Fe content less than 250 ppm by weight and a Na content less than 100 ppm by weight.
  • the aluminum dioxide refractory crown bricks 34 have a Young's Modulus of at least 2 X 10 6 psi and a creep percentage under a 25 psi load at 1600°C for 150 hours of less than 5% creep.
  • the crown bricks 34 are assembled together in a herringbone pattern.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Structural Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Glass Compositions (AREA)
  • Glass Melting And Manufacturing (AREA)
  • Silicon Compounds (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)

Abstract

La présente invention concerne un article composé de silice relativement pure, un four et un procédé de production de cet article. En outre, on produit cet article en récupérant les particules de silice fondue (30) dans un four réfractaire (50) dans lequel au moins une partie du réfractaire (32) a été exposée à un gaz contenant de l'halogène pour réagir avec les ions métalliques contaminants dans le réfractaire (32).
EP00961725A 1999-09-10 2000-09-08 Silice pure fondue, four et procede correspondants Withdrawn EP1242324A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US15342299P 1999-09-10 1999-09-10
US153422P 1999-09-10
PCT/US2000/024776 WO2001017919A1 (fr) 1999-09-10 2000-09-08 Silice pure fondue, four et procede correspondants

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EP1242324A1 true EP1242324A1 (fr) 2002-09-25

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EP (1) EP1242324A1 (fr)
JP (1) JP2003508337A (fr)
KR (1) KR20020029790A (fr)
CN (1) CN1387499A (fr)
AU (1) AU7364000A (fr)
WO (1) WO2001017919A1 (fr)

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Publication number Priority date Publication date Assignee Title
US6732551B2 (en) * 2001-05-04 2004-05-11 Corning Incorporated Method and feedstock for making silica
WO2004092082A1 (fr) * 2003-04-11 2004-10-28 Nikon Corporation Procede de production d'un verre a base de sio2-tio2, verre a base de sio2-tio2 et systeme d'exposition
TW201805246A (zh) * 2016-07-20 2018-02-16 康寧公司 玻璃處理設備及方法
CN112759232A (zh) * 2020-11-19 2021-05-07 晶研一材料科技(宜兴)有限公司 一种微晶陶瓷玻璃的熔炉温度调节方法
CN116750951B (zh) * 2023-05-29 2024-05-10 湖北华强日用玻璃有限公司 一种玻璃窑炉无氧烤窑的方法

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US4600442A (en) * 1984-08-14 1986-07-15 Hughes Aircraft Company Process for the removal of impurities from optical component materials
DE3619510A1 (de) * 1986-06-10 1987-12-17 Philips Patentverwaltung Verfahren zur herstellung von glas- oder keramischen koerpern
US5152819A (en) * 1990-08-16 1992-10-06 Corning Incorporated Method of making fused silica
US5043002A (en) * 1990-08-16 1991-08-27 Corning Incorporated Method of making fused silica by decomposing siloxanes
EP0850201B1 (fr) * 1995-09-12 2003-07-16 Corning Incorporated Bac de production de verre de silice

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See references of WO0117919A1 *

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CN1387499A (zh) 2002-12-25
JP2003508337A (ja) 2003-03-04
WO2001017919A1 (fr) 2001-03-15
KR20020029790A (ko) 2002-04-19
AU7364000A (en) 2001-04-10

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