DE1669553C3 - Process for the production of shaped structures, in particular fibers, from metal oxides and their use - Google Patents

Description

The invention relates to a method for producing shaped structures, in particular fibers, from metal oxides. It also relates to the use of the structures produced in this way.

It is known e.g. B. according to US-PS 6 23 723, mantles by soaking a tissue Manufacture plant fibers with metal salt solutions and ignite and burn the soaked tissue. According to US-PS 32 42 000 and 32 81 261 it is also known to fabric made of viscose rayon or to soak cotton with solutions of titanium or zirconium compounds and then in an inert To heat atmosphere; this creates fibers that essentially consist of carbon and therefore are not stable at elevated temperature in the presence of oxygen. According to US-PS 3111 396 it is also known to use a porous article made of an organic material, e.g. B. a cloth with a pulpy Metal compound, to impregnate and then to char or burn the organic matter; according to this process, porous objects made of metal compounds are obtained.

The object of the invention is a method for the production of shaped structures, in particular of Fibers, made of metal oxides, which are easy to manufacture even in complex shapes, from contiguous Metal oxides exist and have high tensile strength and flexibility.

According to the invention, this object is achieved in that a shaped structure is made from an orgarüschen polymeric material with a solution of one or more penetrating into the polymeric material Compounds of the elements beryllium, magnesium, calcium, strontium, barium, scandium, Yttrium, lanthanum, cerium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, Tungsten, manganese, cobalt, nickel, copper, zinc, cadmium, aluminum, gallium, silicon, tin, lead, Thorium, uranium or plutonium soaks the soaked material and dries it while avoiding inflammation heated so high that the organic material carbonizes and oxidizes, and that the metal compound or the metal compounds are converted into the corresponding oxides, at least part of the heating in the presence of an oxidizing

atmosphere.

The metal oxide fibers of the invention can be in various forms, for example as staple fibers with lengths of 6 mm to 7.5 cm, as continuous fibers or yarns, as

As fabrics, knitted fabrics, braids, felts and the like Non-fibrous moldings produced can, for example, be films, sponges, foams and the like.

The term "amorphous" used here and below means that the metal oxide is essentially is microcrystalline, i.e. That is, that the crystallites have such a small diameter that they can pass through the usual X-ray analysis are hardly recognizable. So you can use the expression "microcrystalline" use in the same sense as the term "amorphous". A poorly visible X-ray grid for a crystalline material means that the individual crystallites have a diameter of 100 Angstrom units or have less. The fibers of the invention made of metal oxides can have crystallites Diameters up to 10,000 Angstrom units, as determined by an X-ray analysis can be seen before their strength decreases significantly. Meanwhile, fibers with crystallites are with Preferred for diameters less than 1000 Angstrom units because of their maximum strength.

According to the invention, the procedure is that a preformed organic polymeric material is first with one or more compounds, preferably with salts or the hydrolysis products of salts, the said metallic elements soaks. The soaked organic material is then heated under controlled conditions that prevent inflammation and at least partially in the presence of an oxidizing gas. Here the organic material becomes predominantly carbon pyrolyzed. This carbon is then removed as a carbon-containing gas, whereby at the same time oxidizes the metal compound or the metal compounds to the corresponding metal oxides will. This creates fibers, textiles or moldings that have essentially the same shape like the polymeric starting material.

The term "preformed" means that the organic polymeric material is formed into a fibrous or non-fibrous form prior to impregnation with the metal compounds.
The external shape of the final metal oxide product

is essentially the same as that of the starting material from the organic polymer; however, the dimensions are significantly reduced. While the treatment of the impregnated organic fibers and during their transformation into fibers made of metal oxide both the diameter and the length shrink to around 40 to 60% of the original dimensions. A similar shrinkage in all directions also takes place in the production of non-fibrous moldings.

If you want to produce a yarn from several continuous fibers of metal oxides, then used the starting material is a yarn made of organic fibers of the same type. Likewise, one can produce a fabric or a felt made of metal oxides as a starting material a fabric or a Use felt made from organic fibers. Of course, textiles made of metal oxide fibers can be made in this way be that one first produces the fibers in the form of staple fibers or continuous yarns and they then woven in the usual way.

The following theoretical explanation may be given for what goes on in the procedure: An organic polymeric material like cellulose consists microscopically of extremely small crystallites in polymeric chains, micelles or microiibrillen, which are in a mass of an amorphous polymer be held together. If you immerse the organic material in a solvent such as water, aqueous solutions or organic solvents, so it swells, with the spaces between the Crystals are opened. The amorphous areas are enlarged, and the spaces between the Crystallites increase. The solved one. Metal compound, e.g. B. a salt, occurs in the swollen amorphous Areas which are generally 50 to 90 percent by volume of the swollen organic material. After removing the solvent, the metal compound remains in the amorphous areas between captured the crystallites.

When the organic material dries, the metal compounds do not crystallize, which usually occurs takes place when the solutions dry out. When using cellulose the metal compounds are finely suspended in particles about 50 Angstrom units in diameter between the crystallites of the polymer.

The organic starting material can also be impregnated with two or more metal compounds from the same solution, so that the end products contain more than one metal oxide. The metal compounds enter the spaces between the crystallites approximately in proportion to their concentration in the solution; this allows the loading of various metal compounds to be regulated. By d ^; With the blocking effect of the organic crystallites, the metal compounds cannot separate from one another and cannot crystallize during the further process steps either.

Any polymeric organic material can be used as the starting material if it has the has the structure described above, i. i.e., if it contains very small crystallites that are swellable in a mass amorphous material are held together. You can also use raw materials that are made from Long-chain, cross-linked molecules exist when these raw materials swell, absorbing the solvent can and do not melt during further processing when heated. As a starting material Any cellulosic material can be used, for example regenerated cellulose, saponified Cellulose acetate, cotton, wood, ramie

and the like. Further suitable organic starting materials are proteinaceous substances such as wool and silk. Furthermore, polyacrylic compounds, polyesters, polyynyl compounds and polyurethanes can be used. Certain organic materials such as polyethylene and

ίο Polypropylene are for the process according to the invention not suitable because they do not swell when soaked with the metal compound and because they also do so possibly melt during pyrolysis and lose their shape. A preferred cellulosic

»Material containing 5 consists of rayon, because it is structurally is uniform, is easy to soak and contains only small amounts of impurities.

The soaking or impregnation of the organic material can be carried out by various methods will. If the element that forms the metal oxides is good in the form of a salt in water is soluble, soaking can be carried out in such a way that the organic material is concentrated in one aqueous solution of the corresponding salt or the

»Dip 5 salts. For example, if you want a fiber made from aluminum oxide, this fiber is soaked by immersing it in an aqueous solution of Aluminum nitrate or aluminum chloride at concentrations of about 2.0 to 3.0 moles of the salt per liter.

In the case of hydrolyzing salts in water, the pH of the impregnation solution should preferably not be below 1.0 to prevent degradation of the organic material during soaking. Possibly the acid can also be neutralized with ammonia.

To achieve a good strength of the end product the cellulose-containing material is soaked with the metal compound in such an amount that for each basic molecule of cellulose at least one molecule, preferably 1.0 to 2.0 molecule, of the Metal compound or metal compounds are omitted. With the expression "basic molecule" becomes a glycosidic unit of the cellulose chain with a molecular weight of 162. Using of non-cellulose! Material you should use such amounts of the soaking salt that each Grams of the organic material at least 0.1, preferably 0.5 to 1.0 gram equivalent of the metal ion available. At lower concentrations of the metal compounds there are so few salts that that the end product is not firm enough and that the yield also decreases.

In order to increase the soaking speed and the amount of salt absorbed, this can

cellulose-containing material must be pre-swollen with water before being immersed in the impregnation solution. To the Aromatic alcohols are suitable for pre-swelling of acrylic and polyester compounds of polyvinyl and polyreethane compounds, ketones can be used.

Water is the preferred solvent for impregnating cellulosic materials with metal compounds. Other solvents such as alcohols do not cause sufficient swelling and solubility

the metal compounds in alcohols is also often low. Solvent for soaking polyvinyl and polyurethane compounds are, for example, esters and ketones such as n-butyl acetate or methylethyl

ketone. Solvent for impregnating polyacrylic and polyester compounds are aromatic alcohols and amines, such as aniline, NitiophenoL m-cresol and p-phenylphenol.

Soaking at room temperatures of 21 to 23 ° C takes a few minutes to several days, depending on the type of salts used and the type of organic starting material ° C from a 3.3 molar solution of uranyl chloride within 30 minutes 0.9 mol of the compound UO ₂ Cl ₂ per basic mole of cellulose. With aluminum chloride from concentrated solutions at 21 ° C, soaking takes longer. Under the same conditions described above for uranyl chloride, a normal viscose fiber pre-swollen with water absorbs only 0.4 mol of A1C1 _S per basic mole of cellulose within 30 minutes. After 3 days of immersion, the fiber has _{absorbed 0.7 moles of AlQ 8} per basic mole of cellulose. Immersion in concentrated salt solutions for longer than 3 days is disadvantageous for substances containing cellulose, since the starting material can be broken down. This leads to a decrease in the amount of salt absorbed and the individual fibers to adhere to one another.

By way of illustration, it should be noted, for example, that in a concentrated solution of zinc chloride the fiber swells rapidly and absorbs _{larger amounts of ZnCl 2.} At a temperature of 21 ° C., a viscose fiber pre-swollen with water absorbs 3.4 mol of ZnCl ₂ per basic mole of cellulose from a 6.8 molar solution. In this treatment, however, the fiber swells essentially to form a gel and becomes sticky. In this condition the fiber is too weak to be processed further and the individual fibers cannot be separated from one another. If such a fiber is to be impregnated with zinc chloride without the fibers breaking down and sticking together, the fiber, which has been pre-swollen with water, is immersed in a 3.6 to 4.0 molar solution for 1 to 3 hours. During this treatment, the fiber absorbs 0.6 to 1.0 mol of ZnCl ₁ per basic mol.

If the impregnation speed is to be increased, the solution of the metal compounds can be heated up to 100.degree. If, for example, salts that are only slowly absorbed by the cellulose fiber are used, such as A1C1 _S , Al (NOg) ₃ , ZrOCl ₂ and ThCl ₄ , the soaking time can be shortened by increasing the temperature of the solution to 50 to 65 ° C one should, however, be careful, as some salts degrade the organic material strongly at elevated temperatures.

Another method of loading organic material is to use in Water-insoluble compounds that hydrolyze with formation, of metal oxides or with water implement. The procedure for using these compounds is described below. Suitable hydrolyzable and / or compounds which react with water are, for example, the following:

1. VOCl ₃ , VCl ₃ , VCl ₄ , which provide the compound V ₂ O ₅ ;

2. NbOCl ₃ , NbCl ₅ , NbBr ₆ , which provide the hydrated Nb ₂ O ₅ ;

3. TaCl ₅ , TaBr ₆ , which is the hydrated Ta ₂ O _s

1 ipf prn _

4. MoCl ₅ , Mo ₂ OjCl ₈ , which provide the hydrated MoO _215- J ₁₀ ;

5. WCl ₈ , Wa ₅ , which provide the hydrated WO ₃ (tungstic acid);

6. SiCL ₁ or silanes such as trimethylsilane, which provide the SiO ₂ .

These metal halides or oxyhalides are dissolved in an organic one which is immiscible with water

ίο liquid such as carbon tetrachloride, chloroform, Carbon disulfide, ethyl ether or benzene in such amounts that the solution per 100 ml of the organic Contains liquid S to SOg of the metal halide or oxyhalide. Then one treats the cellulosic or other organic material with air having a relative humidity of 50 to 90% to swell this material by absorbing 5 to 30% by weight of water. Im swollen State and with the absorbed water becomes

ao the organic material brought into contact with the metal halide or oxyhalide by immersion into a liquid or by contacting with gaseous halides or oxyhalides. When the halide or oxy-

a5 halides in the moist material sets the compound with water, whereby a corresponding oxide is deposited directly in the organic material will. The hydrolysis is usually complete in 20 to 30 minutes.

The amount of metal deposited in the organic material is directly dependent on that in the Material absorbed amount of water. Typical hydrolysis reactions can be expressed by the equations below be reproduced:

SiCl ₄ + 3 H ₂ O

TiCl ₄ + 2H ₂ O

2TaCl ₅ + 5H ₂ O

■ H ₂ SiO ₃ + 4 HCl
TiO ₂ + 4HCl
Ta ₂ O ₅ + 10HCl

The amount of water absorbed by the organic material can easily be controlled by using the Material treated with air with a certain moisture content. To accommodate the maximum Amount of water, the material can also be immersed directly in liquid water. The table below shows what amounts of water are absorbed in commercially available viscose rayon, which is in equilibrium with moist air and liquid water at 24 ° C.

Relative humidity at 24 ° C Moisture content, Percent, based on the dry one Fiber weight 10 4th 30th 8th 50 10 70+ 14th 80 17th 90 23 95 30th 100 (immersed in water) 80 to 110

Certain hydrolyzable metal compounds are liquid under normal conditions. You can do it organic material laden with water directly into the

Immerse the metal compound, whereby the oxide is formed within the material by hydrolysis. Examples of such liquid metal halides are SiCl ₄ , TiCl ₄ , VOCl ₃ and VCl ₄ . In some cases, however, the hydrolysis takes place very quickly with the development of S heat. Here, the organic material can be broken down or broken down. Therefore, it is preferred to dilute the metal compound with a non-reactive liquid to prevent such conditions. Various polar organic liquids can be used for dilution, such as benzene, toluene, hexane, carbon tetrachloride, chloroform. If these organic liquids are used as diluents for the metal compounds, the rate of hydrolysis is reduced and the heat of reaction is dissipated. Unreacted liquid metal compounds and diluents can be removed by evaporation because they have a high vapor pressure.

If you use hydrolyzable metal compounds that are normally not liquid, they are dissolved in non-reactive liquids that are immiscible with water. Such metal compounds are, for example, TaCl ₅ , NbCl ₈ , ZrCl ₄ , UCl ₄ . Suitable solvents are bromoform, carbon ag tetrachloride, diethyl ether and nitrobenzene.

After soaking with the metal compound solution or the metal compounds must remove the excess solution before drying the fibers removed. This avoids caking of the fibers due to salts and an accumulation of dry salt on the surface of the fibers or moldings. One does not leave the absorbed Metal compounds or hydrolysis products back, the resulting end products have a smaller one Strength and greater brittleness. Dabbing with blotting paper or a tissue under moderate Pressure is sufficient to remove the excess liquid from the organic material. Further but also suitable methods are scrubbing, the use of high-speed gas streams, filtration under vacuum or centrifugation. For removing solutions with viscosities greater than about 10 centipoise, e.g., a 3.0 molar solution of aluminum chloride, it is expedient to increase the temperature to 50 to 60 ° C when removing the excess solution.

The soaked organic material is then carefully dried by conventional means, e.g. with Air or in a stream of a tub of gas. You should get the soaked fibers quickly, i.e. within an hour or less to allow the salt to leak out onto the surface impede.

If you want to produce an end product that consists of two or more metal oxides, you soak it organic material with two or more salts or hydrolysis products. If you use two or more water-soluble salts, so you can use a single solution for soaking, e.g. B. an aqueous solution, which contains both salts. Should a mixture of two oxides be obtained, one of which is made up an aqueous solution and the other is introduced by hydrolysis of a halide or oxyhalide is to be soaked first with the hydrolysis product and then with the water-soluble product Salt.

In the next process step to convert the soaked organic material into a metal oxide the soaked material is heated under controlled conditions for so long that the organic Compound is decomposed and a carbon-containing framework is formed, which the metal compound in finely divided Contains shape. Then, possibly at the same time, the carbon is removed and converted the metal compound to the metal oxide.

The working conditions must be such that the organic material does not ignite. In the event of ignition, unregulated temperature increases occur within the material; in In some cases the material burns with a flame. The unregulated one that occurs here Temperature rise is sharply differentiated from the process steps according to the invention. When well managed Working the temperature rise in the impregnated organic material is very uniform with the temperature of the environment, even if the exact temperature inside the organic material something can fluctuate above or below. But if the material ignites or burns, so the temperature of the meta-compound rises very high. Under these circumstances it is not possible to regulate the temperature, and the melting point of the metallic interconnects formed can be exceeded, or there will be strong crystallization and grain growth instead of. The meta-compound can also be suspended and entrained in the hydrolysis vapors, with losses taking place and the resulting carbon-containing framework too little of this metal compound contains. By avoiding inflammation, the end products have a smoother surface and are more solid because the individual particles of the metal compound are better ordered.

In practice, by observing the shrinkage, it can be determined whether there is inflammation has taken place. Without ignition, the organic material will shrink lengthways in the Usually by 40 to 60%>, for example from a length of 10 cm to a length of 5 cm. The end product is firm and microcrystalline, the resulting fibers are very flexible. But if one unwanted ignition has taken place during heating, the material will shrink far less, the final products obtained are crystalline rather than microcrystalline, and they are brittle and of low strength If an ignition takes place towards the end of the heating, the end product can Although it has shrunk considerably, its properties are still poor. In general, it is the amount of shrinkage is inversely proportional to the loading of the metal compound. Preferably one ensures that maximum shrinkage takes place.

When carrying out the method according to the invention, inflammation can be controlled by Working conditions are avoided. In particular, care should be taken to avoid strong sudden Changes in temperature, the composition of the atmosphere and the like do not occur. Such sudden changes easily lead to unregulated temperature rises and thus possibly to inflammation.

For example, one proceeds in such a way that one odei a cellulose-containing fiber with a metal salt impregnated with several metal salts. Then heated

one to a temperature between 350 and 900 ° C with a heating rate of not more than 100 ° C per hour in an atmosphere containing between 5 and 25 volume percent oxygen. If the resulting metal oxide has a decomposition or melting point below 900 ° C, the heating temperature must of course not go beyond this. When the temperature of about 350 ° C. or a little more is reached, a larger part of the cellulose fiber is charred under the working conditions described, and the char is volatilized in the form of a carbon-containing gas by reaction with the oxidizing gas. At the same time, the greater part of the metal compound in the impregnated fiber is oxidized to form metal oxide. The impregnated fiber should, however, be kept in an ^{atmosphere containing an Ä ^ r} o ⁿ ^ ^eS Pf at 350 to 900 C until substantially all of the impregnated fiber is charred and volatilized and until substantially all of the metal ao ™ oxide is oxidized .

After the first slow heating to a temperature above 350 ° C, the atmosphere need not contain less than 25 volume percent oxygen. However, the use of a ₅ * atmosphere bnngt with more than 25 volume percent oxyd.erendes gas no special advantages. Oxygen is preferably used as the oxidizing gas; but you can also use other oxidizing agents

Send '^ R t 5 ^Ι0Χ ί Use sulfur oxide. The rest of the atmosphere is made up of gas

l ^{n Te} 7 ^era T ⁿ f T ^CU " ^{d about it}

In a preferred sführungs A ^ ^ to the invention, a cellulosic fiber bnngt with a compound of the eenannten in Table metals whose oxides have a melting point or decomposition point above 800 ° C. Then Ξ Ξ ER-

to allow faster heating in a vacuum or in an inert atmosphere without ignition

When oxidizing the metal compound to the metal oxide, an oxidizing agent must be used. This is best done by heating the charred and partially oxidized material in an atmosphere containing oxygen or some other oxidizing gas. Here too, of course, inflammation must be avoided. This can be achieved by carefully controlling the temperature, by limiting the amount of oxidizing gas or by using a relatively less reactive oxidizing agent.For example, steam at temperatures above 700 ° C can be used as the oxidizing agent. Particularly good results are achieved by heating the charred material in an inert gas that contains a few percent water vapor

Avoiding ignition by regulating the working conditions is generally easier with fibers and fibrous materials such as textiles than with other non-fibrous molded articles such as, for example, organic foams or sponges that are soaked with metal compounds. For such non-fibrous moldings, a non-oxidizing atmosphere is preferably used for the initial heating and the temperature rise is kept at less than 50 ° C. per hour. After the char is essentially complete, an oxidizing agent can be added to the atmosphere. But also the entire carbonization and ⁰ * y ^dati ° n One can körperndurch- of nichtfLrigen ^

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atmosphere containing the substance at a temperature of 45 _M SrHchTch ^ n H of 400 to 800 ° C until the fiber in neither 7 I

of the organic material is avoided. The process can be regulated in various ways for this purpose, e.g. B. by regulating the temperature! by controlling the amount of oxidizing agent or by using a vacuum or an inert atmosphere. Here it must be noted that oxygen in numerous · organic substances "'ζ B in CeUulose, is included so that a certain amount is an oxidizing agent in the impregnated Sf terials In VerwendungvoTweineren pieces of impregnated" material or you _ch ver ° hältndsmäßig slowly heating Incorrect inflammations are avoided, especially Ws za temperatures of 350 ° C. In some systems 6 _S, for example, especially in the case of soaked cellulose fibers, TZ- it is sufficient, however, to remove the excess solvent in all

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impregnated fibers in an argon atmosphere to be carried out in separate slides

from room temperature to the. If you start heating the soaked

heated to a temperature between 600 and 1000 ° C. Material begins, so is pyrolysis to carbon

Then one oxidizes by holding the fibers at the predominant chemical reaction, and the

about 800 ° C in an argon atmosphere, the low-carbon material consists mainly of carbon

stents contains 5 percent by volume of water vapor, while with small possible residues of organic

one to 10 hours. This procedure shows that material, including hydrogen and oxygen,

there is an ignition even with rapid heating. A certain degree of oxidation of the carbon formed

can prevent if one does not initially find in one of the existing metal but also already

atmosphere reacting to high temperatures 10 takes place here, especially when the atmosphere

heated and then contains an oxidizing atmosphere of an oxidizing gas. If the

relatively low reactivity used. Heating «and when most of the organic

After the third ¹ process, the imprä- material is converted into carbon, all-

gnosed fibers quickly, often within 5 minutes, gradually the oxidation by the oxidizing atmosphere

heated to about 400 ° C in an atmosphere which 15 sphere is the predominant reaction. In the last

Less than about 10 percent by volume of oxygen is produced.

holds. Then one gradually increases the partial pressure dation of the last metal atoms and the last carbon

of oxygen at constant temperature until the only chemical reactions

carbonaceous material and the metal compound In many cases the addition of small quantities facilitates

are oxidized, which _ao is usually ¹ to 3 hours Iz gen of water vapor to the atmosphere, the letz-

contests. This procedure is used to remove traces of carbon,

tion how to prevent one inflammation caused by the oxidation of carbon

direct regulation of the partial pressure of oxygen microscopic gaps ·. A maximum compression

■ η of the area around the fiber. of the material is achieved if · one during the

These various methods described above 25 oxidize the concentration of the oxidizing gas

for the production of fibers from zirconium oxide without keeping the temperature too high. To complete

Inflammation of the organic material can also persist the oxidation are usually 1 to

Applied mutatis mutandis to other fibrous products, 48 hours required, whatever the type of

will. So one can depend on the soaked fibrous metal oxide or the metal oxides. Some

material in a non-oxidizing atmosphere, over 30 metal oxides such as uranium oxide, zirconium oxide, iron oxide,

Certainly using a vacuum or copper oxide, chromium oxide and vanadium oxide,

an inert gas, temperatures between 700 increase the rate of oxidation of the carbon

and 1000 ° C within less than an hour and therefore make it possible to

heat, whereupon you can work at the same temperature ratur. A faster oxidation of the

further heated, using an atmosphere by increasing the concentration of carbon

det, the at least 5 percent by volume of water vapor oxidizing gas or by increasing the temperature

contains. This latter step rarely completes the temperature in the first stages results in a less dense

the oxidation usually takes 1 to 10 hours. tes and less solid metal oxide, what with gaps

But you can also explain the impregnated fiber material in the structure. Relatively high temperatures of about 350 to 600 ° C ₄₀ also favor the formation of heat if an atmosphere is used that contains crystallites in the end product, which should avoid less than about 10 percent by volume of oxygen being released. The compaction of the metal frame continues; then one keeps within the same temperature oxide can be ascertained by shrinking in with a gradual increase of the partial pressure of all dimensions during the oxidation. In the case of Fa-oxygen, until the content of oxygen has reached 20 volumes, but the ratio of length to percent by volume remains; this requires a few knives, as well as the shape of the cross-section of the grooves up to a few hours, depending on the fibers, essentially the same as in the starting materials used. Although one is the par-product.

tial pressure of oxygen within a short time. In a particularly preferred embodiment

can increase, sudden increases should affect the invention for the production of a game from several

be avoided. more metal oxides, if the soaked cellulose

The method according to the invention can also contain yarn continuously during the charring and the oxytic process be performed. You can z. B. dation under tension. Tensions from about 10 to Continuously a yarn made from a metal oxide - 40 g is sufficient for yarn from around 1440 individual places. For this purpose, spooled cellulose threads with 3300 denier are used. As a rule, the au: fibers, yarns or the like. The fiber or the metal oxides existing end according to the invention are passed Yarn first through an impregnation solution, it dabs off products that are essentially amorphous or microcrystalline and dries them and finally leads them through a lini. There is some crystal formation in the end product or several ovens, in which the consents are also permitted. Even after a certain crisis carbonization and / or oxidation with the required 60 installation of the metal oxides has the end product dif borrowed regulated conditions to avoid a desired property. This characteristic Inflammation is taking place. The ones from the last furnace are only significantly deteriorated then, by whom Exiting from metal oxides existing fiber can form so large crystallites that they after the ex Continuously wound onto another reel borrowed microscopic method established who will. 65 den can. In this latter case the one is micro

The charring of the soaked organic macrystalline structure is replaced by the relativelyi]

terials and the removal of the formed coal- large crystalline areas. The properties voi

Substance due to oxidation need not be necessary - fibers made of metal oxides are especially dam

13 14

worse if the diameter of the single crystal melting, but catalytically active metal oxide

lite contains more than a tenth of the fiber diameter.

wearing. Fibers containing uranium oxide or plutonium oxide A very important class of metal oxides in the sense of the invention with diameters of one or a few microns are those that can be used as fuel elements in nuclear reactors 80 percent by weight from one or more Me-, especially in those where taloxides with a melting point above 1728 ° C, "radiation reactions" or a fission carried out, ie the melting point of silicon oxide. should be. The fibers can consist solely of uranium - these preferably include the oxides Al ₂ O ₃ , BeO, oxide or plutonium oxide, they can also consist of CaO, CeO ₂ , MgO, TiO ₂ , ThO ₂ and ZrO ₂ individually from a mixture of these oxides with other substances or in mixtures with one another. These oxides and tallow oxides, such as BeO, Al ₂ O ₃ , ZrO ₂ or ThO ₂ , be-oxide mixtures are chemically very stable and stand. For use as fuel elements in other types of reactors, for research purposes, have strength even at high temperatures. In dense sintered form, these and research purposes, for the generation of oxides, an important class of commercially available electrical energy or the like, can expediently be refractory materials. Fibers made from these refractory materials, these fibers with an impermeable Ma-metal oxides can be coated for the production of heat material, in order to use the escape of structural shields and abrasion-resistant reinforcing materials from the radioactive end products in the cooling stream. One can use them to reinforce art to prevent the reactor. For use with materials even at relatively low temperatures or high temperatures or in a non-oxidizing atmosphere or for reinforcing metal, atmosphere, the uranium dioxide UO _{2 is} the preferred porcelain and other ceramic materials to form; it is obtained by reducing the use of uranium at high temperatures. Test these highly flammable trioxide, UO ₃ with hydrogen at 500 to 600 ° C. Fibers made of metal oxides are excellent. For use as a reactor element under oxydie-filters for corrosive gases and liquids at 25 generating conditions is excellent at elevated temperatures. You can z. B. fiber according to the invention, the 20 to 60 weight molten metals, molten salts, over percent uranium trioxide, the rest, ie 80 to 40 weight filter heated air and exhaust gases from ovens. Except for percent, it contains aluminum oxide or zirconium oxide. Filter purposes are the end products of metal oxides uranium dioxide-containing fibers made of metal oxide according to the invention are also very useful as construction 30 according to the invention are generally useful as elements and for thermal insulation of the high fuel elements in reactors; Fibers from a temperature and in a corrosive environment. So mixture of uranium dioxide and thorium dioxide are z. B. End products that contain cerium oxide, thorium oxide particularly well suited as fuel elements in • nd zirconium oxide, particularly advantageous for breeders.

Use in contact with corrosive or alkali moldings according to the invention made of metal oxides

liquid like electrolytes in batteries. can be used for many purposes. Foils

Fibers made from zirconium oxides are particularly useful; made from metal oxides with a very uniform texture

bar because of their low thermal conductivities, thicknesses down to 10 microns can be considered thin

and their high stability at high temperatures dielectrics or as heat insulating films or

even in an alkaline environment. 40 foils can be used, e.g. B. Films made of aluminum

The well-known production of blocks from cera- oxide or other ceramic oxides. Other

mix materials from linings, crucibles and moldings according to the invention can be used as building

Other more complicated moldings are often elements used, e.g. B. as insulators against

difficult because the melting or sintering too - heat or tension, as partitions in battery

connected bodies is not easy. These 45 and similar sponge-like molded bodies made of metal

Dead shaped bodies are not very resistant. Oxides can also be used as filters. For this purpose

against thermal shock and are used in the case of sudden one preferably as a starting material

Changes in temperature destroyed. If you use cellulosic foam or sponge materials with

but the inventive loose fibers, yarns, open pores of a uniform pore size and

Papers or fabrics, so it is easy to shape 50 a low density.

and related, even complex ones. The following examples illustrate some of the molded bodies to sinter together. One can implement the invention. The specified the substances according to the invention, even thin-walled temperatures, are always the temperatures of the Manufacture pipes, as well as linings for furnaces. The actually prevailing within the material ovens, protective tubes for thermocouples and gui- 55 Seeing temperature can depend on the oven temperature supply pipes for liquid metals. differ slightly.

Some metal oxides with relatively deep ones

Melting or decomposition temperatures, for example Example 1
wise the oxides of vanadium, molybdenum, tungsten, manganese, cobalt, nickel, copper, zinc, cad became viable catalysts. The fibers produced from these oxides according to the invention by immersion in water for four and a half hours have pre-swelled them. After spinning off · the supercatalytic activity and excess water can be used per gram of the yarn like the usual catalysts. So 65 fiber can hold 0.70 g of water. One dipped this yarn with one z. B. with good success as a catalyst use a 22 ° C for 22 hours in a 2.8 molar aqueous fiber, the 80 to 98% of a high-melting solution of aluminum chloride. The excess metal oxide and 20 to 2% of it were then lowered. Tüsnrw ah nnH trnck-

16 69 555

15 16

nete. The yarn contained 0.79 g of aluminum per gram of fiber.

minium chloride and had its original bending work. The felt made of aluminum oxide had

its original shine. A 60 cm weighing 650 g per m * and an apparent

long section of the impregnated yarn had a density of 0.127 g / cm ^s . The felt was very pliable

then- in the air at a temperature rise of 5 and had high strength.

100 ° C per hour heated to 400 ° C and during

two more hours at this temperature from Example 4

400 ° C helda To remove the last traces

of the carbon, the yarn was removed for 6 hours. A 30 χ 30 cm piece of a piece of

heated to 800 ° C in air. Here one held io webes made of regenerated cellulose with a weight

the yarn under a tension of 10 g. of 56.2 g was used. In the weft and in the chain

The aluminum oxide yarn obtained had 7.5 yarns per cm. The tissue was swollen

a high gloss and flexibility that was found in water before and then immersed for 46 hours

Flexibility of the starting material corresponded. That at 22 ° C in a 2.86 molar aqueous solution of

Alumina yarn was 1260 denier and 15 zirconyl chloride. After immersion, the solution

a concentration of 2.55 MqI per liter was found at 46% of its original length. Man

shrinks. In four measurements in one apparatus, the fabric was spun off and kneaded at 50 ° C

according to I η s t r ο η it was found that 5 cm of it was obtained in this way - quickly in circulating air. The dried

Tenen yarn loads of 730, 730, 730 and weave contained 0.96 g of zirconyl chloride per gram. The

Withstood 860 g. Later the tensile strength ao soaked fabric was then gradually in air

measured by single threads from this yarn. Heated at 500 ° C for 30 hours, what a

three measurements it was found that the yarns, temperature increase of about 16 ° C per hour,

without breaking, loads of 900, 730 and spoke. The tissue was held during further

Withstood 590 g. The calculated tensile strength of the 6 hours at a temperature of 500 ° C to the

individual fibers lay between 6000 and 25 last traces of carbon to remove ra. The

9000 kg / cm ² . made of brownish colored zinc oxide i

Example 2 ^we ' ^3e ^^ ^em weight of 14.2 g and each contained

cm about 19 yarns. The fabric was pliable and

This example describes the impregnation and watering had a tear strength of 1.0 to 1.1 kg / cm width,

work from a fabric to a fabric made of aluminum 30 An X-ray analysis showed that the fabric

minium oxide. The starting material was a 41.4 g weight amorphous zirconium oxide and only traces of

Weighing piece with the dimensions 30 χ 30 cm weakly crystallized tetragon alem zirconium oxide

used, which consisted of a yarn from 1100 single.

Threads with 3300 denier consisted, in the weft 7 and in B e i s ρ i e 1 5

the warp contained 3V * yarns. This tissue turned 35

45 g of a viscose fiber of 1.5 denier was swollen by immersing it in water for one hour. After the excess water had been dabbed off and then preswollen with an aqueous solution, the tissue contained 0.81 g of water per gram. The soaked, which contained 0.4 mol of uranyl chloride and pre-swollen tissue per liter, was immersed while 2.8 mol of alumindum chloride, the soaking in an aqueous solution of aluminum 40 ken lasting 48 hours for 65 hours. After the discharge chloride. After the end of the immersion, that of the excess liquid and, after the dissolution, a concentration of 2.5 mol AlCl ₈ in the drying of the fibers in a stream of warm air liters. The excess solution was spun off, heated in the air at a temperature rise from the fabric and dried quickly in a rotation of 50 ° C per hour to 400 ° C. The air was at 50 ° C. The dried fabric was removed further Heated for 4 hours at 400 ° C. in air, held 0.69 g of salt per gram. It was heated while to remove all carbon. The end 48 hours gradually up to 400 ° C in air. The product from metal oxides contained 56.5 percent by weight of the last traces of carbon were replaced by five percent UO ₈ and 43.5 percent by weight Al ₂ O ₈ . The hourly heating in air at 800 ° C removed. The amber-colored fiber had a high gloss, so obtained white alumino oxide fabrics had 50. Its tensile strength was almost as high as that of high gloss and was very flexible. It weighed from aluminum oxide fibers according to Example 1. The weight was 7.1 g and had shrunk to a dimension of approximately mixed oxides had no crystal structure, such as 12 × 12 cm. An X-ray analysis showed to tear.
Weight of 0.65 kg / cm width required. Spec-

The fabric was found trographically to be 55 samples
Contained 99.5% Al ₂ O _8. The greatest pollution

consisted of zinc, which was contained in the starting material. There were four different aqueous solutions

was and also prepared by washing with dilute salt, which per liter are those given below

acid could have been removed. An X-ray mole of the salts contained:

Beam analysis showed that the aluminum oxide was practically 60.

table was amorphous. Only very small amounts of W ² ' ³ ™ ^{o1 A u} · ^un ° "/ l ™ ° ™ ^ *'

crystallized gamma-aluminum oxide were to- ( ^b ) ² > ^{3 Mo1 AIC1} s ^and °> ^{32 Mo1 CrC1} s;

against what is determined by a broad diffraction band- (c) 2.3 mol AlCl ₈ and 0.27 mol IFeCl ₈ ;

was asked. (d) 2.3 moles of AlCl ₈ and 0.33 moles of CuCl ₂ .

^eis P ^ie Four different patterns of common viscose

A felt made of rayon weighing 1000 g per m * fiber with 1.5 denier was pre-swollen and then

was soaked with aluminum chloride and after each in one of the four solutions, for 48 hours

The submerged one removed the excess solution and dried the fibers in warm air The temperature was then increased from 50 ° C. to 400 ° C. per hour and held during this time another 4 hours at this temperature. The four metal oxide fibers each contained 13.0 percent by weight Nickel oxide, 11.7 percent by weight chromium oxide, 15.9 percent by weight iron oxide and 13.2 percent by weight copper oxide, the remainder in each case aluminum oxide. All four fibers so obtained made of mixed oxides had a high tensile strength and were practically amorphous.

Example 7

An incandescent gas sock made of knitted rayon fibers soaked with a thorium compound was made Heated in air to a temperature of 400 ° C for 7 hours and in one for a further 24 hours Oxygen flow kept at this temperature. “° After this treatment was the organic matter completely decomposed and the carbon liquefied. The stocking obtained consisted of white and glossy ones Fibers of amorphous thorium oxide. The stocking was just as flexible as the starting material. When viewed under a microscope at a magnification of 50, the fibers were made of thorium oxide just as transparent to light as window glass.

A second sock impregnated in the same way was burned off, with the oxide quickly becoming with it Flange formation arose. The thorium oxide stocking it contained contained white fibers with a matt shine. The fibers were brittle and poor in strength. An X-ray analysis showed that the thorium oxide was well crystallized. The brittleness and poor strength of when burned The resulting fibers from thorium oxide are to be explained with the crystallization and with a large number of gaps between each crystal. In contrast, they will be useful Properties, d. H. high strength and good flexibility, only when slowly converting to amorphous Metal oxide developed, as the first part of this example shows.

45

Example 8

This example shows the undesirable effects of making a felt from zirconium oxide occur by burning.

Two identical samples of felt from rayon measuring 15 15 cm were placed in the same aqueous 2.17 molar Immersed solution of zirconyl chloride. After 200 hours of immersion, the samples turned off taken from the solution, dabbed off and spun off, whereupon it was dried. The first pattern was then treated according to the invention. The mixture was heated with a temperature increase of 50 ° C. per hour up to 350 ° C and held for 4 hours in air at this temperature. Then you increased them in air Temperature to 600 ° C for 2 hours and held for a further 2 hours at 600 ° C. The second sample was treated as follows. The sample was placed in an oven heated to 800 ° C in air and removed after half an hour.

The product treated according to the invention had shrunk to a size of 5.4 × 5.4 cm, which indicated an average shrinkage of 65%. The other sample had a size of 10.8 X 10.8 cm, which corresponds to an average shrinkage of only 29 ⁰ Z _0. The sample produced according to the invention was strong and flexible, while the sample obtained by burning was very weak and fell apart into crumbs .

Example 9

Cellulose fibers were immersed in an aqueous solution of the chlorides of nickel, zinc and iron In this solution the metals were present in such amounts that they were absorbed by the cellulose The proportions of salts corresponded to the composition of a spinel. After 24 hours Immersion removed the fibers from the solution, dabbed them and hurled them to the remove adhering solution. It was then dried in air at about 50.degree. Subsequently were heated the fibers in air at 350 ° C for 24 hours. The fibers obtained consisted of mixed oxides of nickel, zinc and iron. Only a diffuse diffraction pattern was obtained from an X-ray analysis. The fibers weren't magnetic in contrast to crystalline spinels of the same composition.

Example 10

Several 5 x 5 cm pieces of cellulose film were placed in a 2.0 molar aqueous solution of Immersed aluminum chloride for 18 hours. A cellophane film like the one used for Wrapping of cigarettes is used. Before treatment, he was washed with acetone to get rid of remove the moisture-repellent paint from the surface. After immersion, you wiped the unabsorbed solution and dried in a desicator between two pieces of paper to to keep the film flat. Then the pieces were heated with an hourly increase in temperature from 10 ° C in air to 365 ° C and held at this temperature for 8 hours. Then continued Heated to 800 ° C for 20 hours to remove the last traces of carbon.

The films obtained were smooth and about 2 by 2 cm in size; their thickness was 10 to 12 microns. The films were pliable, colorless, and as transparent as window glass. They consisted of very weakly crystalline gamma aluminum oxide of 97 ⁰ Zo purity.

Example 11

Three pieces of the cellulose film described in Example 10 were immersed in an aqueous solution containing 2.0 mol of aluminum chloride per liter and Contained 0.08 mol of uranyl chloride. After immersion, the excess liquid was wiped off, and the films were dried between papers in a desicator. With an increase in temperature from 10 ° C hourly, the films were heated in air to 365 ° C and for 8 hours at this Temperature held.

Smooth yielded 12 microns thick films that were about 50 ⁰ / o shrunk by its original dimensions. The films were very smooth, transparent and yellowish in color. They consisted of 27 percent by weight of UO ₃ and 72 percent

weight percent Al ₂ Oj. One
showed that they were amorphous.

X-ray analysis

Example 12

A piece of foam made of a foly ether, 3.0 X 3.1 χ 1.5 cm, with open cells was immersed in a solution of uranyl nitrate hexahydrate in n-butyl acetate, each 100 ml containing 60 g of the salt contained. The immersion time was 1 hour. The piece was then blotted and dried.

The impregnated piece was then placed in a vacuum tube furnace with a temperature increase of Heated 40 ° C hourly to 900 ° C and kept at this temperature for 1 hour. The charred Foam was then held at 750 ° C. Air was slowly passed over for 4 hours to remove the To oxidize carbon.

The final product obtained was about 70% of its original size, had the same open cell structure of about 91 "open cells, the cells being 50 to 75 microns in diameter. The color was blackish green, indicating that it was Compound U ₈ O ₈ , acted.

Claims (4)

Patent claims: 1. Process for the production of shaped structures, in particular fibers, from metal oxides, characterized in that a shaped structure made of an organic polymeric material with one in the polymer Material penetrating solution of one or more compounds of the elements beryllium, magnesium, Calcium, strontium, barium, scandium, yttrium, lanthanum, cerium, titanium, zirconium, Hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, cobalt, nickel, copper, Zinc, cadmium, aluminum, gallium, silicon, tin, lead, thorium, uranium or plutonium soaks, the soaked material dries and heats it so high, avoiding inflammation, that the organic material carbonizes and oxidizes and that the metal compound or the Metal compounds are converted into the corresponding oxides, at least one Part of the heating is carried out in the presence of an oxidizing atmosphere. 2. The method according to claim 1, characterized in that there is used as the shaped structure ceilulosic fiber material and a compound de ^c zirconium as the metal compound. 3. The method according to claim 1 or 2, characterized in that there is a shaped structure Cellulose fibers are used and the impregnated fibers are kept under tension when heated. 4. The use of structures obtained by the method according to any one of claims 1 to 3 have been made, as a partition in batteries.