DD202135A5 - MOLDED MECHANICAL STABILITY PARTS AT HIGH TEMPERATURES, METHOD FOR THEIR PRODUCTION AND THEIR USE - Google Patents

Abstract

A molding made from a mixture of 100 parts by weight of ceramic fibers or a mixture of at least 20% by weight of fibers and at most 80% by weight fired fiber composite, 2-20 parts by weight of clay or finely divided refractory oxides or hydroxides, at least 2 parts by weight of binder and water, d. Mixture compacted, dried and / or fired. The moldings and in particular plates have a bulk density of 0.5-1.8, a high mechanical stability and good insulating properties.

Description

9 Q7 0 7 P Ε "- / - AP C 04 Β / 237 378/5

Berlin * the 30 * 6 _β 82 AP C 04 year 60 418 18

Moldings with high mechanical stability at high temperatures

Field of application of the invention

The invention relates to molded parts with high mechanical stability at high temperatures »a process for their preparation and their use *

Characteristic of the well-known _L> Xgjc.hji _o ischen Lö

Heat-insulating ceramic fiber bodies of refractory fibers _t: organic or inorganic binder on the one hand low strength and high Zusarzmendrückbarkeit and on the other hand, increased values for the strength _f density and dimensional stability are known * Thus, DE-AS 1 274 490 describes a combustion chamber for ovens _s by shaping the binder mass is formed * and in which the binder concentration over the cross-section of the wall is to decrease * A suitable binder is Tone ,. Alkali silicates ₉ aluminum phosphate, colloidal silica with a weight fraction of 5 to 35 , optimally 10 % _v called "The fiber body is however because of its dense hard wall surface and the opposite soft flexible Vyandoberflache not sufficiently for high loads sufficiently suitable"

In the process according to DE-AS 2,732,387, the mineral fibrous plate prebound with an organic plastic binder is intended to be solidified by drenching with an aqueous slurry of a binding clay and subsequent tempering. "Furthermore, European patent application

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0006362 Plates are known which contain in a matrix of a plastic clay reinforcing vitreous inorganic fibers. The amounts of clay in this case are in a range of 29 to 80% by weight and the amount of glassy inorganic fibers in the range of 15 to 55 wt _s -% of the plate "

Object of the invention

The aim of the invention is the provision of molded parts with improved mechanical and thermal properties, which can be used in particular as E _r rate for lightweight blanks «

Explanation of the essence of the invention

The invention has for its object to find a suitable composition of the molded parts with improved mechanical and thermal properties, which can be used in particular as a substitute for lightweight blanks _s «can be produced

According to the invention, molded parts with high mechanical stability at high temperatures are produced from the following composition:

100 parts by weight of either ceramic fibers, or one

Mixture consisting of at least 20% by weight of fibers and up to 80% by weight of a fired fiber grain,

2-20 weight parts by _e clay and / or finely disintegrated Al ₂ O ₃ and /

or finely divided SiO _? and / or aluminum

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miniumhydroxiden and / or finely divided magnesia and / or finely divided titanium dioxide and / or finely divided chromium oxide ,

8 O- "calculated parts by phosphate binder than ₅ ^p ₂ ^ 5» 0-10 wt "parts by an organic binder" and 0-10 "parts by other refractory additives _s are however at least 2 weight * parts by a binder present .

a density of 0 ₉ 5 to 1.8

a hot bending strength at 1000 C of at least 0.8 N / mm ² _s

a TWB of at least 25 air quenching *

The erfindungsgeraäßen moldings are prepared in such a way that

a) 100 Gewo Part either ceramic fibers or a mixture of s consisting of at least 20 percent by _e -% fibers, and up to 80 percent by _e -% of a fired fiber grains with 2 20 wt _e parts by clay and / or finely disintegrated Al ₂ O ₃ and / or finely disintegrated SiO ₂ and / or aluminum hydroxides and / or finely divided magnesia and / or finely disintegrated titanium dioxide and / or finely disintegrated chromium oxides 0-8 wt ~ _e parts of phosphate binder, calculated as P ₃ O _5, O lö Gewe- parts of an organic binder, _a but using at least 2 _s are present by weight parts by _e, and a binder are mixed thoroughly 0-10 wt _e -Teiien other refractory additives and water in a blender _e

737

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b) the mixture obtained in step a) by a volume factor of at least 3 with the sole use of ceramic fibers or by a volume factor of at least 1.5 using a Geräisches 80 Gew "parts fiber grain and 20 wt * parts of ceramic fibers Forming is condensed, and

c) the molded part produced in step b) is dried and / or tempered and / or fired »

The moldings according to the invention can be used for many purposes " in particular as a substitute for known light-blast panels," Their advantage here is that they have a lower density than these and they have a very narrow pore size distribution and small pore size. Despite the densification, their thermal conductivity is of the same order of magnitude as that of non-compressed, known per se, molded parts made of glass fibers, which were produced by a vacuum suction method. Compared with these, however, the moldings according to the invention have a much higher strength.

Due to their high mechanical strength moldings of the invention are particularly suitable as expansion joints filler between the stones of rotary kiln. Asbestos has been used for this, but the use of asbestos is increasingly being rejected because of its harmful effects «

As inorganic fibers, the moldings according to the invention can be any conventional ceramic fibers, such as rock wool or fibers based on aluminum silicate with an AlpO ^ content of about 40 to 95% by weight.

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The * other refractory additives used in the molded parts according to the invention are the additives usually used as fiber mold dividers, such as porcelain flour * chamotte »hollow spherical corundum or vermiculite«

The binders present in the molded parts according to the invention are phosphate-containing binders, z * B * boron phosphate, aluminum phosphate or sodium polyphosphate having a degree of polymerization of η = 4 and in particular η ^ 6 to IG *

The organic binders present in the moldings according to the invention are the binders customarily used in refractory or fire-resistant moldings, such as starch, spent sulphite liquor, molasses and, in particular, methylcellulose. "The stated amount of binder refers to solid, organic binder, ie without water content.

Both the phosphate binder and the organic binder can be added both in dissolved form and in solid form, but when using methylcellulose _3, which is usually added as a 5% by weight aqueous solution, part of this methylcellulose _f is advantageously added in particular larger amounts of methyl cellulose * used as an organic binder in solid, finely divided form otherwise the amount of water introduced into the composition via such a binder solution would become too great *

The clay present in the composition of the molded parts according to the invention and / or the finely divided Al 2 O 3 and / or the very finely divided SiO 2 _. and / or the aluminum hydroxides

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and / or the finely divided magnesia and / or the finely divided titanium dioxide and / or the finely divided chromium oxide are known components used in the refractory field. If clay is used, this is a customary binding clay or a preferably used, special one Clay, such as Bentonite "As used herein, the term" finely divided "in the context of the aforementioned ingredients means that these ingredients are in the finely ground or colloidal state, particularly when such colloidal materials are used Colloidal SiO or »colloidal alumina, it is possible to use only small amounts of binder, namely close to the lower limit of 2 parts by weight of such a binder. Either the binder may be existing only of a phosphate binder or only of an organic binder, but advantageously is a mixture of both phosphate binder and organic binder is employed, the use of about equal weight _e parts by Phosphatbindemittei and methylcellulose is especially preferred as organic binder *

Advantageously, the composition of the moldings according to the invention contains 5 to 15 parts by weight of clay or of the other constituents mentioned per 100 parts by weight of the ceramic fibers. Particularly advantageous is the use of a mixture of clay and in particular of bentonite and 1 to 3 parts by weight. Part of one of the abovementioned constituents, in particular colloidal silica,

In the production of the molded parts according to the invention, the ceramic fibers or the mixture of ceramic fibers

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and the burned fiber grain, the clay or the other aforementioned constituents, the optionally used other refractory additives and the organic binder used if necessary gegehsnenfalls a Geraisch prepared with the addition of water * If the phosphate binder and / or the organic binder already in the form of a solution ₃ usually an aqueous solution _t " the addition of water may not be necessary * In the preparation in step a) of erfindungsgeraäßen method are usually in the mixture 5 to 25 parts by weight of water per 100 Gew * T _e ile the ceramic fibers before, phosphate binders such as Natriurnpolyphosphat and Monoaluminiuraphosphat and organic binders such as sulfite waste liquor or methyl cellulose can be used in solid, ground form "it is also possible" a part of these binders in the form of a solution and the rest Part to be added in solid form «

The fired fiber grain used in the production of the molded parts according to the invention is described in more detail in the applicant's German patent application P 3 105 579.6-45 of the same date

a) 100 parts by weight of ceramic fibers, 2 to 15 parts by weight of clay and / or finely divided Al _? 0 ^ and / or finely divided SiO "and / or aluminum hydroxide and / or finely divided magnesia and / or finely divided titanium dioxide and / or finely divided chromium oxide _a optionally up to 10 percent by _e parts by other refractory additives and 1 to 8 wt _e parts by phosphate binders, optionally with the addition of Plastif izierungsrnittel _s with

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237378

about 2 to 25 parts by weight of water are thoroughly mixed in a mixer,

b) the mixture obtained in step a) is compressed by a volume factor of at least 3, and

c) if desired, the product obtained in stage b) is dried and calcined at temperatures of 800 to 1,550 ^° C. and then comminuted to the desired grain size. «

The materials used in the preparation of this fiber graining ceramic fibers, clay or »the other ingredients mentioned, the refractory additives and the phosphate binder correspond to the materials as described above« As a plasticizer, preferably methylcellulose is used. In the production of the fiber granulation, the compaction in stage b) can be carried out in an extruder, a rotary table press or a briquetting device. The mixing of the constituents in stage a) in the production of this fiber granulation can be carried out in any suitable mixer, for example in a Drais "Advantageously, fibers prepared as ceramic fibers are used in the production of such a fiber grain, as they can also be used in the production of the molded parts according to the invention." The comminution in step c) in the production of this fiber grain can be carried out in any suitable apparatus. the maximum grain size is usually 6 mm * However, this comminution can also be set to a certain range, for example, a product with a grain size between 2 and 3 mm easily by crushing in conventional crushing equipment and Aussi if necessary just the desired grain size

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The granular material obtained here has a density of 0.7 to 1.75 g / cm and has a pore volume of the order of 35-75 % . The amount of the optionally added in step a) in the manufacture of fiber granulation plasticizer depends on the type used in the step b) compressing means from * For example, when using methylcellulose and compaction in an extrusion press is added an amount of 4 percent by "parts by methylcellulose _s wherein half of these methylcellulose amount than 5% ± ge solution in water and the other half is added as a dry methyl cellulose "If the compression is carried out in an extruder _s may be up to 100-turn parts, the amount of water used in step a), however.

The amount of water used in the production of Forrateile invention should be kept as low as possible, advantageously only up to 15 parts by weight of water per 100 parts by weight of the ceramic fibers and more preferably only 10 parts by weight of water per 100 wt _e ~ parts of the ceramic fibers zugemischtv so that a dough-like mass is obtained "

The advantage of using a mixture of ceramic fibers and a F _a serkörnung lies _s that in the production of the moldings according to the invention a smaller amount of water must be used "The amount of water in this case depends on the proportion of ceramic fibers and fired fiber grain size in the mixture, wherein the required amount of water is so small, the greater the proportion of fired fiber grain in the mixture is "Particularly advantageous, the use of a mixture of

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50% by weight of ceramic fibers and 50% by weight of the burned fiber grains were exposed.

The doughy mass obtained in step a) in the production of the moldings is filled in step b) of the process according to the invention in a suitable press »for example a platen press or table press or even an isostatic press, and for a suitable period of time, these Depending on the type of press used, pressed "In a platen press, the pressing time is usually 5 to 20 seconds.

It is essential that in the production of the molding according to the invention in step b) the compression by a volume factor of at least 3 with the sole use of ceramic fibers or by a volume factor of at least 1.5 using a mixture of 80 parts by weight of fired fiber grains and 20 parts by weight of ceramic fibers »When using a mixture of ceramic fibers and burnt fiber grains in other proportions, this minimum compaction factor is between 3 and 1.5. Advantageous values for the compaction factor are between values when using ceramic fibers alone 5 and 8 and when using a mixture of 80 parts by weight of fiber grain and 20 parts by weight of ceramic fibers at 2.5 to 4. Of course, in other proportions of ceramic fibers and fired fiber grains in a mixture, the advantageous compression factors between the previously indicated borderline Erten,

/ o

"7%

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The maximum volume factor of the compaction is about 12 to 14 when using ceramic fibers alone, whereas when using a mixture of 80 parts by weight of fiber grains and 20 parts by weight of ceramic fibers, the values are from S to 8.

If the molded parts according to the invention are produced in the form of fibreboards, they can have a thickness of 1 to 50 mm *

After the press, the moldings in step c) of the process according to the invention at higher temperatures "advantageously between 110 and 180 C dried, then they can be tempered at temperatures between 250 ⁰ C and 600 C or at temperatures between 800 C and 1 650 be ⁰ C burned "However, the maximum firing temperature, as well as the application limit temperature mainly depends on the starting mixture used in the ceramic fibers from _e to a lesser Mase of the optionally present other refractory additives"

Ceramic fibers are in their delivery in the form of a loose wool, which, however, some are highly compressed ,. the fibers are before ^ · To an RRC ch better bonding of the fibers by the binder used and good wetting by liquids is surface in the lowest concentration to allow advantageously prepared before shaping, "

For this purpose, mixing units with rapidly rotating mixer heads, so-called turbomixers, can be used, whereby the existing in the delivery state of the fibers, larger

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Agglomerates are disrupted without the fibers being crushed inadmissibly

In the method according to the invention, if no burned fiber granulation is used, it is possible to carry out the step a) also in such a turbomixer, a mixer with rapidly rotating cutter heads, this means that the fiber is broken up and mixed with the other ingredients added in this stage a), namely clay and / or the other components mentioned, optionally phosphate binder, other refractory additives, optionally the organic binder. "In this case, however, only dry solids are added, on the one hand the digestion of the agglomerated Fibers and the homogeneous mixing of the added substances to be accomplished · Then then water and optionally used in the form of solution binder are sprayed into the mixing container and further mixed-mixed *

Of course, it is also possible first to carry out the digestion of the ceramic fibers in a turbo mixer and then the other additives add "This operation is in another mixer, such _# as a Drais mixer or an Eirich mixer especially when using vermiculite or hollow spherical corundum being used as further refractory additives, since otherwise these substances would be broken up, likewise when using a fired fiber grain mixture mixed with ceramic fibers. "

The moldings according to the invention have the particular advantage that, because of the relatively high content of ceramic

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mix fibers very good thermal insulation properties and still have a relatively good mechanical stability due to the compaction and a volume factor of at least 3 or * 1.5 in their production. Furthermore, its thermal shock resistance (TWB) is excellent and is more than 25 cycles,

ausf ührunpsbeispiel

The invention will be explained in more detail with reference to the following examples.

In the examples, ceramic fibers of the system Al 0, SiO _{0 were} used, namely a fiber material A with 47 % Al ₀ OJ

ο 53 % SiOpj operating temperature up to 1 260 C and one for higher

Operating temperatures suitable fiber material B with 95 O ₃ and 5 %

The mixtures were partially prepared in a turbomixer equipped with a rapidly rotating cutter head (3000 rpm). In this mixer, the fiber material is once well digested and, on the other hand, a pourable and free-flowing fiber granulate uniformly interspersed with the mixture components forms. The mixture of fiber granules results in the further processing by pressing to fiber materials with low to high bulk density and particularly homogeneous texture "with a mixer that has at relatively low speed rotating mixing arms" z, B ₉ Eirich mixer _s , however, a less intensive digestion of the fibers and a not so homogeneous preparation of the mixture achieved »The 50% monoaluminium phosphate solution in the mixer in the range of fast

2373 7

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rotating cutter head introduced as spray mist. As a result, complete wetting of the agglomerate surfaces is achieved with the least possible volume of liquid, eg, B _# 10 % by weight of MAP = 6.6 liters. Water is similarly sprayed in the same way. The water dissolves any dry methylcellulose that may be present a good green strength of the moldings *

Manufacture of fiber- reinforced plastics:

a) 100 parts by weight of the ceramic fibers A) * 10 parts by weight of binding acetone having an Al "0 ₃ " content of 35% by weight and 1.5 parts by weight of dry methylcellulose in powder form in an Eirich Mixer was added and mixed together for 10 minutes. Then, 10 parts by weight of 50 weight percent monoaluminum phosphate solution and 2 weight parts of water were sprayed onto the mass in the mixer with continued mixing and mixed for an additional 30 minutes.

The product taken out of the mixer was at a

Pressing pressure of 30 N / mm pressed in a platen press to a plate-shaped product with a thickness of 30 mm, wherein a compression by a factor of 5.5 was obtained.

The resulting plate-shaped product was then dried at 110 C for 24 hours in an oven and then fired at different temperatures for 24 hours and then comminuted to a maximum grain size of 3 mm.

The grain had the following properties:

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* J * U. <J - 15 - Table I

firing temperature ( ⁰ C) 8oo .34 1 350 1 510 Kornrauragewicht R (g / cm ³ ) 1 60 1 , 52 1 77 specific gravity S (g / cm) 2 .7 2 70 2 75 Pg (Vol.-95) 47 43 , 7 35 , 6

b) The procedure of preparation a) was repeated, but using a turbo-mixer with the fiber in it. The pressing pressure in step b) was 10 or 15 N / mm., the compression was at a factor of 4 or 5, respectively .

After a fire at 1 350 C for 24 hours and crushing, a granulation having the following properties was obtained

Table II

Pressing pressure (N / mm ² ) R (g / cm ³ )

spec «weight (g / cm) Pg (VoU-%)

c) The procedure of preparation a) was repeated, but the proportion of Honoaluminiumphosphatlösung increased to 15 parts by weight and the proportion of water to 5 parts by weight with 20 minutes shortened mixing time * After a fire at 1350 ° C. during 24 hours and crushing to the desired grain size, this had the following characteristics;

10 , 7 15 , 02 O , 7 1 , 7 2 2 74 63

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- 16 Table III

R (g / cm ³ ) 1.29

S (g / cm ³ ) 2.69

Pg (Vol.-35) 53.8

d) The procedure of preparation a) was repeated, but still 8 parts by weight of gravel powder were added in the first stage. Furthermore, only 8.3 parts by weight of 50% by weight monoaluminum phosphate solution but 4 parts by weight of water were added in the mixing step.

The compression pressure in the compression stage was 30 N / nm, which resulted in a compression by a volume factor of 5.2.

The resulting plate-shaped product was dried at 180 ^° C. and samples were fired at the different temperatures given in the following Table IV. Subsequently, the dried or burned product was comminuted to a maximum particle size of 3 mm.

The obtained granulation had the following properties:

Table IV

Treatment Temp. ( ⁰ C) Grain weight, R, (g / cm ³ ) spec. Wt., (G / cra ³ ) Pg, (% by volume)

The invention will be explained in more detail with reference to the following examples.

180 30 800 , 26 1200 , 31 1300 , 34 1500 48 1 60 1 60 1 65 1 , 68 1 72 2 , 0 2 , 5 2 , 5 2 , 0 2 , 6 50 51 50 50 45

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example 1

The following approach was used:

Wt, -Τeilο

Ceramic fibers A 100

_(e with 47 wt -% Al ₂ O ₃₎

Bindeton 10

(with 35 wt% _e ~ Al ₂ O ₃₎

Methylcellulose _? dry 1.5

Mono aluminum phosphate solution

_E 50 wt -% ig 10

Water 2

The ceramic fibers A were charged to the Eirich mixer with the binding clay and dry methylcellulose and treated therein for 20 minutes to give a homogeneous mixture. Then, with the mixer still running, the monoaluminum phosphate solution and then the water were sprayed on and thoroughly mixed further.

Subsequently, at a pressure of 30 N / mm was pressed to stones with the dimensions 405 χ 135 χ 50 mm »The compression factor was 6.0 ,.

Subsequently, the stones were dried for 4 hours at 110 C and then fired at different temperatures for different times

The properties measured after firing at different firing temperatures on the bricks were as follows:

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Table V

800 6 h

C /

1350 6 h

C /

1510 6 h

R (g / cm ⁰ ) Pg (vol%) VM (N / mm ² ) KBF (N / mra ² )

TWB

HBF, 1000 ^° C. (N / mm ² ) HBF, 1200 ^° C. (N / mm ² )

1.34 47.7 1408

5.0> 25

4.7

6.2

1.52

43.7

1303

4.4

> 25

6.6

5.9

1.77 35 * 6 5291

8.2

> 25

11.6

9.6

Shrinkage after 24 h at

1400 ⁰ C 1500 ° C 1600 ⁰ C

-3.19

-6.94

-10.32

-1.89

-3.35

- 7,70

-0.16

-5.45

Chemical analysis: Al ₂ O ₃ (%)

P ₂ O ₅ (SK)

44.7 50.7 2.95

Thermal conductivity, WLF, (W / m ⁰ K at 700 ⁰ C)

0.45

Example 2

The same mixture resulted in preparation in the turbo mixer and low pressing pressure after firing at 1350 ° C to stones with the following properties, the properties of the

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Are listed Preßdrück 30 N / mm in Table V to compare with:

Table VI

Example 1 B 20 ερ «2 10 Pressing pressure (N / mm ² ) 30 5.4 15 3.5 compression factor 6, o 1350 4.4 1350 Firing temperature ( ⁰ C) 1350 24 1350 24 Burning time (h) 6 1.34 24 0.7 R (G / cm ³ ) 1.52 58.0 1.02 74.0 Pg (% by volume) 43.7 4.1 63, 0 0.7 KBF (N / mm ² ) 4.4 - ° * ⁹ 0.8 HBF, 1000 ^° C. (N / mm ² ) 6.6 5.6 2.0 " HBF, 1200 ^° C (N / mm ² ) 5.9 - - 0.9 HBF, 1400 ^° C. (N / mm ² ) - 0.25 2.3 0 * 16 WLF, (W / m ⁰ K at 700 ^° C.) 0.45 0.20

Example 3

The following approach was used:

Wt a-T Ceramic fibers A (with 47 wt% Al ₂ O ₃ ) 100

ball clay

(with 35 wt% Al ₂ O ₃ ) 10

Methylcellulose, dry l _t 5

Mono aluminum phosphate "

solution, 50% by weight 15

Water 5

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2373 78 5

- 20 -

In step a) of the process according to the invention, an Eirich mixer was used. First, the dry ingredients were added to the Eirich mixer and mixed for 10 minutes, then the monoaluminum phosphate solution and then the water was sprayed on. After further mixing for 20 minutes, the mass was taken out of the mixer *

As in Example 1 above, the mixture was in a press at a pressure of 30 N / r compression factor was 5.2.

pressed to stones at a pressure of 30 N / mm »Der

The pressed stones were dried at 110 C for 4 hours, then they were fired at 1350 C for 6 hours.

The properties determined on the stones obtained were as follows:

Table VII

R (g / cm ³ ) l _t 29

Pg (vol.%) 53.8 HBF at 1000 ° C (N / mm ² ) 2.1

KBF (N / mm ² ) 2.6

WLF (W / m ⁰ K at 700 ^° C.) 0.35

A comparison of the stones produced according to Examples 1, 2 and 3 shows that in the preparation in a turbo mixer and the same pressure molding moldings with higher cold bending strength can be obtained. When processing in an Eirich mixer, d. H. without digestion of the ceramic fibers, it is expedient, the proportion of phosphate binder and

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- 21 -

also increase the water content slightly, the water content should zweckmäßicerweise are 8 to 10%.

Examples 4 and 5

The following approaches were used:

Ceramic fibers B (with 95% by weight)

ball clay

_(e with 35 wt -% methyl cellulose, dry

Monoaluminum urophosphate solution, 50% by weight

water

Parts by weight

100

10

1.5

.12

100

10

1.5

15

The preparation of the approach in step a) was carried out according to the procedure of Example 2 ₉ h »h. using a turbo mixer «

The mixture obtained in step a) was prepared according to the procedure of Example 2 at a pressure of

2 or * 20 N / mm pressed into stones, then 4 hours

dried at 110 ⁰ C and for 24 hours at 1350 ⁰ G burned "The thus obtained properties of the bricks were as follows:

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*, J - 22 Table VIII Ex.

R (g / cm ³ ) 0.52 1.01

Compaction factor 3.5 6.7

Pg (vol. &) 84.2 69.4

KBF (N / mm ² ) 0.9 1.9

HBF, 900 ^° C (N / mm ² ) 3,4

HBF ₁ 1000 ⁰ C (N / mm ² ) 0.8

HBF, 1400 ^° C (N / mm ² ) 0.7

WLF (W / m ⁰ K at 700 ^° C.) 0.19 0.35

Examples 6 to 9:

The following approach was used:

Gev ^ parts Ceramic fibers A) (with 47 % w / w ^A1 ₂ ° ₃ ) ²⁵

Ceramic fibers B) 75

(with 95% by weight of ^Al ₂ ° 3)

Bindeton '5

(with 35 wt.% Al ₂ O ₃ )

very finely ground alumina, <44> by 5

Methylcellulose, dry 1.5

Monoaluminiumphosphat-

solution, 50% by weight 10

Water 2

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Accordingly oer procedure of Example 2, the mixture of Example 6 in a turbo-mixer was processed and where indicated in the following Table IX pressing pressure pressed into bricks in accordance with the procedure of Example 1 "In Examples 7 to 9 was an Eirich mixer used

After drying at 110 C for 4 hours, it was baked at different temperatures, also indicated in the table, for 24 hours. The properties of the stones obtained here are given in the table «

Instead of stones with the dimensions given in Example 1, the mixtures given here were also pressed into plates with the dimensions 350 × 360 × 18 mm in a hydraulic plate press. Such plates are excellent kiln furniture for firing fine ceramic products or porcelain.

Table IX

Ex., 6 7 8 9

Pressing pressure (N / mm ² ) 8 30 30 30

Compaction factor 3.8 5.3 5.3 5.3

Drying ( ⁰ C) 110 110 110 110

Firing temperature ( ⁰ C) 1350 1520 1580 1520

Properties j

R (g / cm ³ )

Pg (vol .-%) KBF (N / mm ² ) HBF ₄ 1000 ° C (N / mm ² )

O , 57 1 , 22 1 , 22 1 , 31 79 * 9 62 ,1 62 * 2 59 3 O .4 3 _S 5 3 »6 4 2 O ,8th

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- 24 -

Table IX (continued)

Eg 6 7 8

HBFv 1400 ⁰ C (N / mm ² ) 0 ^, 8 4.5 4.9 5.6

WLF (W / m ⁰ K at 700 ^° C.) 0.22 0.47 0.49 0.53

Example 10

The following approach was used:

Weight "parts by

Fiber graining a) _ 80

Ceramic fibers B) 20

Bindeton with 35 % Al ₂ O ₃ 5

very finely ground alumina, ^ - 44 / order 5

finely ground chromium oxide, <; 44 to 2 monoaluminum phosphate

solution (50% by weight) 5

Sodium polyphosphate, solid 0.5

Water 5

The fiber grain, the clay, the clay and the chromium oxide were charged with the solid sodium polyphosphate in an Eirich mixer, then 5 parts by weight of water were sprayed and mixed for 5 minutes. Then, the 20 parts by weight of the ceramic fibers B ) was added, mixed for an additional 10 minutes, then the monoaluminum phosphate solution was added and mixed for a further 10 minutes. The mixture taken from the mixer was pressed at a pressure of 30 N / mm to plates of 405 χ 135 χ 15 mm, then dried for 24 hours at 110 ⁰ C and 8 S _t unden at 800 ⁰ C or, 1350 ⁰ C fired , On the obtained product, the following properties were determined:

800 1350 1.8 , 1.8 2.0 2.0 35 * 8 35.8 2, 6 5 6.4 4.5 7.0 0.70 0.55

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Tab ell.e _X

Firing temperature ( ⁰ C) R (g / cm ³ )

compression factor

Fg (vol ") KBF (N / mm ²⁾ HBF: * 1000 ⁰ C (N / mm ²⁾ WLF (W / m K ⁰ at 700 ° C)

Example 11

The following approach was used:

Weight "parts by

Ceramic fibers A) 100

Hollow sphere corundum, <3 mm 10

Clay with 35 % Al ₂ O ₃ 5

Magnesia 2

Boron phosphate, solid 4,5

Water 9

The fibers were first digested for 10 minutes in a turbo-mixer. Then hollow ball corundum, clay and water were added to an Eirich mixer, mixed for 5 minutes, then magnesia and boron phosphate were added and mixed for a further 5 minutes. Thereafter, the fibers digested in the turbo-blender were poured into input the Eirich mixer and mix for another 20 minutes *

From the obtained mixture, plates were prepared according to the procedure of Example 10. These were after

237378 5

AP C 04 B / 237 378/5 60 418 18

- 26 -

fired drying at 120 ⁰ C at 800 ° C and 1350 ° C "to the obtained product, the following properties were determined:

Table XI

Firing temperature (° C)

R (g / cm ³ )

Compression factor Pg (vol.-ft)

HSF, 1000 ° C (N / mm ²⁾ WLF (W / m K ⁰ at 700 ⁰ C)

800 1350 1.15 1.18 4.1 4.1 51.9 54.6 2.8 4.1 0.63 0.65

Example 12

The following approach was used

Weight "parts by

Ceramic fibers A) 100

Bindeton 10

Sulfite waste liquor, dry 9

Water 9

In an Eirich mixer, the ceramic fibers, the clay and the solid sulfite waste liquor were mixed for 10 minutes, then the water was sprayed on and dried for a further 10 minutes.

mixed. At a pressure of 30 N / mm stones were pressed as in Example 1. "After drying at 110 ⁰ C for 24 hours, these stones were respectively at 800 ⁰ C, 1350 C fired" On the stones following properties were determined *

AP C 04 B / 237 378/5 60 418 18

Table XII

Firing temperature (C)

R (g / cm ³ )

Compression factor Pg (VoL-%)

HBF 1000 ⁰ C (N / mm ²⁾ WLF (W / m ° K at 700 ⁰ C))

800 1350 1.18 1.28 5.1 5.1 54.6 52.6 1.5 2.9 0.27 0.28

Claims (10)

- 28 invention claim 1 "molded part with high mechanical stability at high temperatures, characterized in that it is made of the following composition: 100 parts by weight of either ceramic fibers or a Mixture consisting of at least% by weight of fibers and up to 50% by weight of a fired fiber granulation, 2. Molding according to item 1, characterized in that it contains bentonite as clay. 2-20 parts by weight of clay and / or finely divided Al ₂ O ₃ and / or very finely divided SiO ₂ and / or aluminum hydroxides and / or finely divided magnesia and / or finely divided titanium dioxide and / or finely divided chromium oxide, 0-8 wt _# parts by phosphate binders, calculated as P ₂ O ₅ . 0-10 parts by weight of an organic binder, and 0-10 parts by weight of other refractory additives; however, at least 2 parts by weight of a binder are present, with: a density of 0.5 to 1.8 a hot bending strength at 1000 C of at least 0 * 8 N / mm ² , a TWB of at least 25 air quenchings. 3 * molded part according to item 1, characterized in that it as AP C 04 B / 237 378/5 60 418 18 ~ 29 - further refractory additive porcelain meal, chamotte or hollow spherical corundum contains * 4 * molded article according to item 1, characterized in that it contains sodium polyphosphate or monoaluminium phosphate as phosphate binder « 5 molded article according to item 1, characterized in that it contains methylcellulose as organic binder, 6 «Process for the preparation of a molding according to item I _1, characterized in that a) 100 GeWe parts either ceramic fibers or a mixture consisting of at least 20% by weight of fibers and up to 80% by weight of a fired fiber grain with 2-20 parts by weight of clay and / or finely divided Al ₃ O. ₃ and / or very finely divided SiO 2 and / or aluminum hydroxides and / or finely divided magnesia and / or finely divided titanium dioxide and / or finely divided chromium oxide, 0-8 parts by weight of phosphate binder, calculated as ^p ₂ ° 5 * 0-10 wt * Parting an organic binder, but leaving at least 2 parts by weight of a binder and thoroughly mixing 0-10 parts by weight of other refractory additives and water in a mixer, b) the mixture obtained in step a) by a volume factor of at least 3 with the sole use of ceramic fibers or by a volume factor of at least 1.5 using a mixture of 80 wt "parts fiber grain and 20 parts by weight of ceramic fibers Forming is condensed »and AP C 04 B / 237 378/5 2373 7 8 5 ... "*" " c) the molded part produced in step b) is dried and / or tempered and / or fired » 7, the method according to item 6, characterized in that the compression in step b) by a factor of 5 to 8 with the sole use of ceramic fibers or in order
a factor of 2.5 to 4 is used when using a mixture of 80 parts by weight of fiber granulation and 20 parts by weight of ceramic fibers » 8. Method according to item 6 or 7, characterized by
that the compression in stage b) to produce
Fibreboard is performed, 9 · Method according to item 6, characterized in that fibers processed as ceramic fibers are used » Use of the molded parts according to one of the items 1 to 5, characterized in that they are used as kiln furniture,
d * h. Documents for objects to be burned are used «