Classifications

• • 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
  • C04B30/00—Compositions for artificial stone, not containing binders
  • C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
• • 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
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
  • C04B35/62231—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on oxide ceramics
  • C04B35/62236—Fibres based on aluminium oxide
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/19—Inorganic fiber

Definitions

• refractory fibers Most of these fibers were obtained by melting refractory materials, for example, dehydrated kaolinic clay, sometimes enriched with alumina, followed by blowing a jet of the molten refractory into fibers by techniques similar to those used in the glass, slag, and rock-fiber industries.
• Another technique which is apparently less widespread, consists in concentrating a solution of an aluminum salt, generally the oxychloride, until a viscous mass is obtained which is capable of being converted into fibers by any suitable means, such as blowing, centrifuging, and so on.
• Fibers made according to these two processes are marketed either in bulk or in the form of webs or felts. Webs are obtained by sucking fibers as they are produced onto grids. This technique has a serious drawback: The various layers of fibers forming the web are not joined or secured together. Hence, these webs tend to cleave, preventing their being used in numerous applications.
• webs and even felts can be manufactured with fibers orientated in all directions, the various techniques consisting of dispersing the unitary fibers in water and gathering these dispersions on a filter to form webs or felt.
• These methods have two disadvantages; they partly destroy the fibers and they require the addition of organic binder materials which burn away at elevated temperatures.
• the good cold bending and tensile strengths of the webs and felts largely disappear when the temperature exceeds 350 C. and they become brittle and friable.
• the process of this invention consists in manufacturing refractory felt from fiber such as those fibers, for example, disclosed in our U.S. application Ser. No. 720,324, filed Apr. 10, 1968, entitled Catalytic Mineral Fibers and Their Preparation. That application discloses substantially insoluble refractory mineral fibers having a large specific surface and containing more than 70 percent, preferably 80 to 95 percent, of alumina, the remainder being constituted by at least one other refractory, for example, a catalytic oxide and a method of making them.
• the web made from these fibers is treated for a period of from 0.5 to 2 hours by compressing by rolling at a pressure less than 20 grams per square centimeter and at a temperature between 1,200 and 1,300 C.
• the process according to this invention is suitable for continuous manufacture, as can be seen from the following more detailed description.
• An aqueous solution containing at least aluminum oxychloride, silica, and optionally soluble refractory oxide salts, batched to enable the desired final chemical composition is concentrated to a viscosity of 150 to 200 poises.
• a continuous web is produced the width of which may exceed 1 meter. Its thickness may preferably range from 50 to mm.
• the web is composed of intermingled fibers the diameter of which is preferably smaller than 10 and the length of which may range from a few centimeters to more than one meter.
• This primary web of soluble fibers should preferably have an apparent specific gravity between 0.02 and 0.04.
• this primary web is continuously treated in a current of water vapor at 350 C. *-20 C. for from 2 to 12 hours, so as to obtain a secondary web of fibers having a large specific surface, preferably greater than 70 square meters per gram, and composed of insoluble oxides.
• This treatment is accompanied by homogeneous linear shrinkage of from 20 0t 25 percent.
• This secondary web is then subjected to continuous rolling at low pressure for from 0.5 to 2 hours at a temperature in excess of 1200" C. and preferably from 1,200 to l,300 C.
• the apparent density of the final web thus obtained increases with the rolling pressure. It amounts to about 0.07 to 0.15 for a pressure between 2 and 20 grams per square centimeter. It may be lower than 0.07 for lower rolling pressures.
• Limit temperature of use 1,500 0: Percent A1 0 8095 S10 5-20 (2) Limit temperature of use: at least 1,600" C.:
• additions such as silica and chromium oxide, may also be replaced at least partially by other oxides, such as zirconlurn and/ or thorium oxides.
• the process according to this invention for making refractory felts may be a continuous process, for example, a continuous secondary web may be continuously moved through an elongated furnace in which the Web is heated to a temperature in excess of 1,200 C. and moved under refractory rollers which are secured within the furnace.
• the following example relates to the manufacture of a refractory felt of type 2.
• the primary web After drying at 80 C. for 6 hours, the primary web is treated at 350 C. for 8 hours in a current of water vapor at atmospheric pressure.
• the hydrates, chlorides, and oxychlorides are entirely converted into insoluble oxides.
• the linear shrinkage in this stage amounts to 20 percent.
• this secondary web is subjected in a roller furnace to heat treatment for 45 minutes at 1,250 C. under a mechanical pressure of grams per square centimeter. A further linear shrinkage of 12 percent is effected, together with incipient sintering of the fibers to one another.
• a method of making a refractory felt comprising at least 70 percent alumina, by weight comprising the steps of:
• refractory fibers comprise in addition to alumina, silica and at least one other refractory oxide.
• refractory fibers comprise from to percent, by weight, alumina.
• a method of making a refractory felt comprising at least 70 percent alumina, by weight comprising the steps of (1) forming an aqueous solution comprising aluminum oxychloride (2) concentrating the solution (3) forming fibers from the solution and gathering them in a primary web of soluble fibers (4) drying the web and then treating it in water vapor at elevated temperatures to form a secondary web of insoluble fibers (5) treating the secondary web for a period of 0.5 to

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Inorganic Fibers (AREA)
• Nonwoven Fabrics (AREA)
• Paper (AREA)
• Compositions Of Oxide Ceramics (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8647735

Family Applications (1)

Country Status (9)

Cited By (6)

Families Citing this family (9)

• 1968
  • 1968-03-20 FR FR144519A patent/FR1568996A/fr not_active Expired
• 1969
  • 1969-02-11 NL NL6902117A patent/NL6902117A/xx unknown
  • 1969-02-14 ES ES363686A patent/ES363686A1/es not_active Expired
  • 1969-03-04 US US804268A patent/US3585153A/en not_active Expired - Lifetime
  • 1969-03-07 BE BE729519D patent/BE729519A/xx not_active IP Right Cessation
  • 1969-03-13 DE DE1912628A patent/DE1912628C3/de not_active Expired
  • 1969-03-17 LU LU58218D patent/LU58218A1/xx unknown
  • 1969-03-18 CH CH408169A patent/CH507884A/fr not_active IP Right Cessation
  • 1969-03-18 GB GB04129/69A patent/GB1217828A/en not_active Expired

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