DE2037963A1 - Inorganic fibers - Google Patents

Description

PATENT LAWYERS DR.-ING. H. FINCKE a Munich 5, ³ &

DIP L. -ING. H. BOHR Möllerstraee

DIPL-ING. S. STAEGER long-distance call: "26 60 60

nappe 22338 - Dr Case MD 22099

Imperial Chemical Industries Ltd «London, Great Britain

Inorganic gases

Priority: 1.8. 1969 - Great Britain

The invention relates to inorganic fibers and, more particularly, to the manufacture of refractory fibers from metal oxides.

Metal oxide fibers are currently made by the molten oxide is spun or the oxide is precipitated from the steam. Both procedures are technical difficult and expensive. In addition, the fibers produced from the melts are glasses that are relatively bad possess physical properties.

It was found that fibers from the oxides of

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Metals can be produced conveniently and inexpensively from aqueous solutions of certain inorganic salts.

Thus, according to the invention, a method for the production of an inorganic fiber is proposed, which is carried out by converting a fiber from an aqueous solution of a salt of at least one of the metals aluminum, magnesium, beryllium, cerium, chromium, hafnium, thorium, titanium, uranium or zirconium, wherein the anionic component consists partially or completely of a formate ion, producing, heating the fiber to form an oxide of the metal and then heated, the fiber still further to a higher temperature in the range of .850 to 2000 ⁰ C.

For example, a formate, Hjdro ^ -Formiai ^ HaIogeno-formate, Sulfo formate or acetate formate salt of metals mentioned are used. Salts of these anions and aluminum or zircon are particularly useful in the preparation of aluminum oxide or zirconium oxide fibers

The aqueous solution can! _S are prepared by dissolving the salt or salt mixture in water, "but it is preferred that the salts in situ by h @ Raust rush in that the metal or one of its compounds" ^w i® sB "the metal hydroxide , in formic acid or is © inea? -mixture of formic acid and hydrochloric acid, sulfuric acid «ad / © of the acetic acid dissolves. It is also expedient to produce the SaIs ia G @@@ awart of water by double conversion voa ot © ± maä © i? © a Salsen which contain the ion of the metal b & w “the anionic constituent. An example is the production of aluminum formate by means of double Uasetsüag tos Galeiraaf © nsiat and aluminum sulfate in the presence of ¥ a © s @ gv moderately, the solution after
have been filtered, ctareh
for example by IMiit ^ e
up to 110 ⁰ C, whereby one is gefeeasafalls «, t« iremijKtatem Brück

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is working. It is preferred to use the solution prior to preparation to filter and / or deaerate the lasers «So that the aqueous solution is suitable for the production of fibers, it is preferred that they have a viscosity of 200 to 500,000 at the temperature at which the fibers are made Centipoise and especially from 1,000 to 200,000 gentipoise.

The fibers can be extracted from the aqueous solution by any convenient means Process can be produced, for example by centrifugal spinning, blowing, drawing or extrusion through a Spinneret plate. The fibers are best made at room temperature, but if desired they can also be made at another temperature at which the solution is stable.

It is preferred to dry the fibers prior to the heating carried out to produce the oxide, for example by applying a vacuum or maintaining a humidity of less than 50% in the chamber in which the fibers are collected or by heating , to temperatures of, for example, 90 to 100 ⁰ G.

The temperature to which the fiber is heated to produce the oxide depends on the decomposition temperature of the salt or salts of which the fiber is made. Usually a temperature in the range of 90 to 500 ⁰ G is required to produce the oxide. For example, aluminum formate is heated to a temperature of 90 to 250 ⁰ C. The duration of the heating is preferably 5 minutes to 300 minutes, and the further heating (calcination) is preferably carried out in an oxidizing atmosphere. The duration of this calcination is preferably 10 minutes to 5 hours.

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The oxide production uad the Galeiaiarimgsistiafes, ko ° & n @ n becoming combined into a single operation @ a ₉ i3ad @ a sam the fiber from the temperature at which they hergestollt iÄ & i? & _E to a temperature of "up to 2.000 ⁰ G while © ims © SSeltsmffli © tob for at least 30 minutes
Observe 5 min and 5 hours

During the * heating koaa, © a di © JPaassssa @ ia @ s> are thrown »Swar ist & ± ®mh® ± ά®% · ! © ^ st ^ I fibers not w © igea" feli © hi ₉ $ ® ä @ © h uiM fei @ 2% © ig © tJoMali © l. © ia © greater orientation α <& τ fei ^ tallit © is &<βέ · Fas © ^

Various additions k © aa @ a ia di © fasoss © isgsits ^ sitst was that by giving this © ^ iia! At® © "ö © iiip! © liii-j @ l © ® d® ^ Logiaag gn = der die bevel ^ a 3h © i? g © iit @ llt w © s> d®ao B®ispl © le additives, the old advantage "w®Ti-m && ®t ιι®τα, ® & kosasa ^

(a) Kornwaonstumeinhib ItOi ¹ ^ a ₉ wi ©

oxide or fine (b) (c)

dioxide; (d) oriented aaisoiaet ^ iiieh © tierung of the crystallites as sB g

glasses, di © by, SInroTbelaaadltsag "wq & Glarjsotil.

The fibers produced by the process according to the invention usually have a medium © Durcfea © ®®® ^ ¹ v®a 1 r * to 50A. However, the experience pertains to the production of fibers with this DBirol] M © ss © Ä @ rsick b ^ sctelnkt; <>

The fibers consist of the oxide of the i-metal or metals, that or those in the original SaIs or in the original salts were present- The oxide shows the

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Form a dense polycrystalline mass that is very contains small crystallites. The fibers are stable and solid even at high temperatures · You can, for example for fireproof insulation or as a reinforcing agent for Resins, metals and ceramic materials can be used. They can also be used as catalysts and / or catalyst supports for a wide variety of chemical reactions will.

The invention is illustrated in more detail by the following examples.

example 1

1 part by weight of an aqueous solution of aluminum sulfate was mixed with 2 parts by weight of an aqueous solution of calcium formate. The resulting mixture was filtered to separate the precipitated calcium sulfate. The filtrate was evaporated at 5O ° C under reduced pressure to obtain a viscous solution was obtained containing 81 wt -.% Solid contained which 21 wt .-% AIPO, was equivalent · This solution was extruded through a spinneret plate, and the leaving Fiber was pulled down to a diameter of 5 Å. This fiber was ^{dried at 100 °} C. for 10 min and then ^{heated to 200 °} C. for 10 min, during which the material of the fiber decomposed to form the oxide. The oxide fiber was calcined at 125 ° C for 4 hours to obtain a strong polycrystalline fiber.

Example 2

An aluminum sulfo formate solution containing 4.7% by weight of aluminum, expressed as AlgO ,, and 1.5% by weight of SO ^ ions, was concentrated to a solution by heating under reduced pressure had a viscosity of 200,000 centipoiee from which fibers could be drawn

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At this viscosity the solution contained 60% solids by weight, which 18 wt .-% AIgO, and 5.7 wt .-% SO ^ -Ioaen was equivalent »The solution was by extrusion into dry Air processed into fibers, with a stamp spinning device - device connected to a spinneret plate was used. The glassy ones made on this titmouse Fibers contained the equivalent of 31 wt.% AlgO ^ and 9% by weight SO ^ ions and had an average diameter of 10 / (· They were raised to 1 * 1Q0®G for 45 min

Maintained at this temperature for 1 hour in order to achieve the

Formate to decompose in aluminum oxide, wödiareh, sehlisßlicb, Crystalline alumina fibers were obtained.

Example 3

Freshly precipitated aqueous ZiÄoiadioxid was © in formic acid, the solution was filtered "ad was pntrat concentrated ₉ by it became a Vakuusprsrdampfung subjected itotö a Lösimg having a viscosity of 800 centipoise herzustelleso slides. © Losnag. © ia a Zentrifugalspinnmasehlne" rersp © aa <i® ₉ wob ©! f @ iae fibers were obtained _o Di © lasera tnKdes gssaimelt imd

2 st to 120 ° G and then, 4 st to 1 _O 5QQ®6 © Äitato-There were strong polycrystalline © FaseEa from SiÄ © 3sdi @ sid © Aalt es ο

Example 4-

Example 3 was repeated, from the time you d @ a lat © n © hi @ d "that 5 ß © w. fine magnesia dioxide of the iosiaas w © i? ü.® & KoagsatrieSiaag STa- were set »Ss was a ZiÄ © adi®si <äfa © © sa ®it @ ia © K> lbdsse ren strength than that ¥ on example ©! 3

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Claims (24)

Claims 1. A process for the production of inorganic fibers, characterized in that a Paser from an aqueous Solution of a salt of one or more of the metals aluminum, magnesium, beryllium, oer, chromium, hafnium, thorium, Iitan, uranium or zircon, whereby the anionic constituent partly or completely consists of a formation, manufactures the fiber to form an oxide from the metal heated and further heated the fiber to a higher temperature in the range of 850 to 2,000 ° 0. 2. The method according to claim 1, characterized in that the salt is a hydroxy formate, a halogeno formate Sulfo formate or an acetate formate is used. 3. The method according to claim 1 or 2, characterized in that the salt solution is prepared by a process in which the metal or one of its compounds in formic acid or a mixture of formic acid and hydrochloric acid, Sulfuric acid and / or acetic acid is swallowed. 4-. Method according to claim 2, characterized in that that the salt solution is prepared by a process in which a double reaction of two other salts is carried out, which contain the ion of the metal or the anionic component. 5 · The method according to claim 4, characterized in that an aluminum formate solution by double conversion of calcium formate and aluminum sulfate in the presence of Water is produced. 109808/2099 * 6. The method according to any one of the preceding claims, characterized in that the aqueous solution is concentrated before fibers are made from it. 7. The method according to claim 6, characterized in that the aqueous solution is concentrated by evaporation. 8. The method according to claim 7 »characterized in that the aqueous solution is evaporated by heating it to a temperature of 30 to 110 ° C. 9. The method according to any one of the preceding claims, characterized in that the aqueous solution is filtered. 10. Method according to one of the preceding claims, characterized in that the aqueous solution is deaerated. 11. The method according to any one of the preceding claims, characterized in that the aqueous solution at the temperature at which the fibers are made has a viscosity of from 200 to 500,000 centipoise. 12. The method according to claim 11, characterized in that the aqueous solution has a viscosity of 1,000 to 200,000 Having centipoise. 13 · · Process according to one of the preceding claims, characterized in that the fiber is produced by centrifugal spinning, Drawing or extrusion is made through a spinneret plate. 14. The method according to any one of the preceding claims, characterized in that the fiber before heating, in the the oxide is formed is dried. 109808/2099 15 · The method according to claim 14, characterized in that the fiber is dried by heating. 16. The method according to claim 14, characterized in that the fiber is dried by adding moisture exposed to less than 50%. 17 · Method according to one of the preceding claims, characterized in characterized in that the oxide of the metal is produced by heating the fiber to a temperature of 90 to 500 ° C is heated. 18. The method according to any one of the preceding claims, characterized characterized in that the oxide of the metal is made by heating the fiber for 5 minutes to 300 minutes. 19 · Method according to one of the preceding claims, characterized in characterized in that the fiber is further heated under oxidizing conditions. 20. The method according to any one of the preceding claims, characterized characterized in that the fiber continues for 10 minutes to 5 hours is heated. 21. The method according to any one of the preceding claims, characterized in that an additive is added to the aqueous solution is incorporated. 22. The method according to claim 21, characterized in that the additive consists of fine magnesium oxide. 23 · Method according to claim 21, characterized in that the additive consists of fine or colloidal silicon dioxide. 24. The method according to any one of the preceding claims, 109808/2099 --ίο - ■ 20379 by gßhi] <i ~ lcQi®hM.w'is% dal eia © Hass © !? mils © Sa @ m aittls ^ en! diameter ύοώ. 1 to 50 ß !