EP1934156A1

EP1934156A1 - Ceramic from preceramic paper or board structures, process for producing it and its use

Info

Publication number: EP1934156A1
Application number: EP06777091A
Authority: EP
Inventors: Andreas Hofenauer; Renate Kirmeier; Ralf Markusch; Hans Windsheimer; Nahum Travitzky; Peter Greil
Original assignee: Pts (papiertechnische Stiftung) Muenchen
Current assignee: Pts (papiertechnische Stiftung) Muenchen
Priority date: 2005-10-12
Filing date: 2006-08-28
Publication date: 2008-06-25
Also published as: DE102006022598A1; DE102006022598B4; US8048544B2; US20090011208A1; WO2007042105A1

Abstract

The invention relates to a ceramic from preceramic paper or board structures in a particular shape previously represented in a paper structure, in which, according to the invention, the preceramic papers or boards have a content of ceramic fillers of from 30 to 95% by mass, with the ceramic fillers having a particle size of < 30 µm. Furthermore, the invention relates to a process for producing such ceramics and their use.

Description

Ceramics made of preceramic paper or cardboard structures, process for their preparation and their use

The invention relates to a ceramic of pre-ceramic paper or cardboard structures, a method for producing such ceramics and their use.

Porous ceramics are used in the art for numerous applications, such as thermal insulation structures, kiln furniture, pore burner substrates and fire protection structures. Another field of application is in the field of catalyst supports.

It is already known to dip corrugated board bodies or other paper structures into a slurry of metallic or ceramic powders to form an outer coating (Sieber, T. Fey, D. Schwarze, M. Weidner and M. Kresch; Ceramics from Paper Structures ", in" Das Keramikerjahrbuch 2002 ", publisher: H. Reh, Göller Verlag, Baden-Baden / Germany, pages 47-54 (2003)). The corresponding dipped papers are then subjected to pyrolysis in inert gas and a subsequent temperature treatment at 1400 ⁰ C in the air. In this process tion are already high temperature resistant, cellular ceramics with relatively low weight. Disadvantage of the previously known method is that on the one hand, the coating to be made is relatively expensive. Furthermore, no coating with the reactive substances is possible inside the paper structure. In addition, a coating is only possible for bodies that are submersible. However, this excludes any type of hollow bodies, in which the slip can not penetrate. Furthermore, in a coating of fine structures, such as a fine wave in the corrugated board, a uniform coating of the surface by immersion in the slurry is no longer guaranteed.

The object of the invention is to provide a ceramic of preceramic paper or cardboard structures in a specific shape previously imaged in a paper structure, with which any body can be produced.

According to the invention this object is achieved by a ceramic having the features of claim 1.

Accordingly, a ceramic of preceramic paper and cardboard structures is created in a certain form, previously imaged in a paper structure, in which the preceramic papers or paperboards have a content of ceramic fillers between 30 and 95 mass%, the ceramic fillers having a particle size <30 have μm.

According to the invention, therefore, "filled papers" or "filled boards" are produced, which are enriched to a large extent with ceramic filler.

Advantageously, the ceramic may be formed in the form of a previously illustrated paper or cardboard structure as a composite ceramic.

Fillers used in ceramics may be selected from a group of the following: carbides, nitrides, oxides, borides and / or zeolites. Particularly suitable as fillers Al ₂ O ₃ , ZrO ₂ , SiC, Si ₃ N ₄ , TiO ₂ , B ₄ C, TiC, TiB ₂ and mixtures thereof and / or glasses such as aluminosilicates.

In order to increase the retention of the fillers in the preceramic paper or in the preceramic cardboard, ie to enable a high loading of the preceramic paper or the preceramic paperboard with the fillers, according to a particularly advantageous embodiment of the invention, loaded latex or charged starch Combined with a charged polymer in the mixture. The proportion of latex in the preceramic paper or in the preceramic paperboard is between 0.2 and 15% by mass. The proportion of polymer in the preceramic paper or in the preceramic paperboard is advantageously between 0.05 and 5 mass%.

As reinforcing elements ceramic fibers may be added.

As pulp, any pulps, such as sulfate pulps, sulfite pulps, TMP and / or CTMP can be used. The thickness of the preceramic paper structure is advantageously in the range of 50 to 500 μm. The weight of the preceramic paper structure is in the range of 100 to 500 g / m ² .

It is also possible to produce preceramic paperboard structures which are comparatively thick-walled and are, for example, up to about 50 mm thick.

According to the invention, the above-described ceramic is produced by the following method:

Mixture of pulp and filler, processing into a paper or a cardboard,

Exposure of the paper or paperboard produced to pyrolysis at temperatures up to 1200 ^° C. and / or Sintering at temperatures between 100O ⁰ C and 2000 ⁰ C.

Advantageously, the prepared base paper or the produced raw board is subjected to a molding step before the pyrolysis steps, for example a corrugation or a corrugated board production.

Advantageously, the individual layers of papers or paperboards can be gummed to obtain thicker layers. In this case, differently structured ceramic paper or paperboard can be particularly vergautscht together. As a result, a alternating-layer ceramic can be produced. The preceramic paper or the preceramic paperboard produced in this way can additionally be coated with ceramic slips by means of an established paper coating technique. The aim is the production of multi-layer systems. In the green or sintered state of the preceramic paper or the preceramic cardboard layers can be applied by means of sol-gel technique.

The preceramic paper or the preceramic paperboard can be processed by means of established papermaking techniques or paperboard forming techniques in order to produce a thin-walled, possibly complex-shaped structured ceramic. It is particularly advantageous that the use of paper joining techniques is possible here.

Comparatively thick-walled boards can be produced with the aid of, for example, multilayer embossing, twin-wire presses or card corrugators.

These boards can be thermally converted into plate-shaped ceramic products. Such large-area ceramic plates are for example as lining elements of chemically, mechanically or thermally stressed line constructions of great interest. In the thermal reaction, a reaction or removal of the pulp and the latex takes place first by means of pyrolysis and oxidation. Subsequently, depending on the ceramic system, it is sintered under inert conditions or in air.

For the pyrolysis and the debinding process temperatures up to about 1200 ⁰ C are necessary, whereby the pyrolysis takes place under inert conditions (eg nitrogen atmosphere) and the debinding process under air or oxygen. In contrast, temperatures between 1000 ° C and 2000 ⁰ C must be observed for the sintering process.

Depending on the starting mixture, density as well as porous ceramics can be realized. The microstructure of the resulting ceramic then over the pulp and thus after appropriate pyrolysis the remaining voids, the filler content, the particle size distribution of the filler, the degree of compaction or the nature or proportion of other additives, such as long or short ceramic fibers, fiber fabrics, platelets, Whisker and / or organic fibers (as placeholders) of the paper can be set in a wider range.

The corresponding thermal conversion of paper structures makes it possible to realize complex-shaped three-dimensional ceramic structures.

Advantageous uses of the ceramic according to the invention will become apparent from the claims 20 to 22. In the gas separation or liquid filtration, the ceramic according to the invention can be used advantageously. Such ceramic membranes are used in micro-, ultra- and nanofiltration. Here flat, large-scale filter designs are sought, which are not feasible by conservative methods, such as extrusion. The advantage of using the above-mentioned method according to the invention is that large-area, thin ceramic substrates can be produced and can be realized by means of paper-coating methods in multilayer systems. The thickness of the ceramic substrates is below 500 microns for papers, but up to 50 mm for paperboard. Another application according to the invention is the use as a pore burner. Ceramic pore burner systems can be used in a new temperature range up to much higher temperatures than metallic systems. It can be achieved here about 2000 ⁰ C with ceramic systems. The pore size of such burner systems is in the range between 2 and 6 mm. In addition to foam structures, wave structures can also be used. Such wave structures can be effectively achieved with paper technical design.

Finally, an inventive use of the present invention in the field of thin-walled and dense construction ceramics. Thin-walled or dense ceramic elements are of great interest, for example, as components for ceramic heat exchangers.

By using suitable bonding layers, laminate ceramics can also be produced from the preceramic papers or boards according to the invention.

In this case, ceramics convertible, advantageously layered material is bonded / connected by the connecting layers and converted in a subsequent temperature treatment in ceramics, whereby a permanent, solid and temperature-resistant connection between the converted into ceramic material layers and also converted into ceramic connecting layers is achieved.

Laminated ceramic bodies are well established in the art, but their production sometimes requires great technical effort. Thus, techniques such as hot pressing of slip infiltrated and impregnated fiber preforms are used in the manufacture of ceramic composites. However, such methods are mostly limited by the use of a KalWHeißpressschrittes in the geometry of the components to be created, here only simple geometries such as plates can be realized. An innovative step for the creation of components with a complicated shape is the application of rapid prototyping methods. Through such methods, technical components can be created without a mold. Above all, the Laminated Object Manufacturing (LOM) method is suitable for this because comparatively large components can be created. As starting materials in this case, for example, paper webs are used, which are mechanically laminated by the action of temperature and pressure and then cut to size. By means of temperature and pressure, the adhesive applied to the underside of the paper layers is briefly melted and, after solidification, forms a permanent bond between the paper layers. With a cutting device, the component outline is cut into each material layer, in this way the component is generated additively in layers.

Is used as the starting material of the LOM process, a ceramizable, planar substrate, such. As ceramic films or preceramic papers or cardboard used, so ceramic components can be made very easily in this way. Since this process does not require the use of a molding or molding tool ("mold"), any complicated components can be made quickly and inexpensively.

In the tie layers of the present invention, polymer-based adhesive bonds are used for layered ceramic components (laminate ceramics). Since thermoplastic / thermosetting adhesives at high temperatures (> 800 ⁰ C), as they are necessary for the consolidation of a ceramic molding, thermally decomposed, adhesives must be used, which are assembled so that they have a high enough residue at high temperatures ,

Therefore, the bonding layer according to the invention consists proportionately of a powdery polymer solid at room temperature, which softens by the action of heat and solidifies again after the end of the temperature. Just- Thus, silicone or phenolic resins, which exhibit a thermoplastic behavior up to the crosslinking temperature, can be used.

The ceramic yield after a temperature treatment is adjusted by introducing fillers. Thereafter, the starting polymer is homogeneously enriched with filler particles, advantageously with particle sizes of less than 50 μm.

Advantageously, the filler particles used are ceramizable filler particles and thus the connecting layer can also be ceramized.

The proportion of the introduced filler particles can advantageously be up to 90% by mass, based on the dry mass of the polymer used.

The use of the dry bonding layers with ceramic yield makes it possible to connect ceramic surfaces by briefly softening and solidifying.

Thus, there are ceramizable bonding layers which, after a deposition step, form a permanent bond with the corresponding substrate materials and with which a plurality of substrate layers can be bonded by the action of temperature. Said compound layers have a ceramic yield after a high-temperature treatment, which can be influenced by the amount of the ceramic fillers added.

Sheet materials coated with the adhesive layer of the invention may then be laminated, inter alia, but not limited to, by the LOM process for the purpose of component fabrication. This results in components with layer structure, which are shown schematically in Figure 1. By appropriate choice of the composition, thickness and porosity of substrate and adhesive layer, among other things, graded structures (functionally graded materials, FGM) can be obtained. The adhesive bond according to the invention can also find a wide field of application in ceramic technology, for. B. for the connection or fixation of catalyst parts, soot particle filters or as a fixing aid for furnace linings. The present invention also allows for the choice of appropriate starting materials for use in fuel cell technology for the provision of electrolyte layers. Another field of application of the invention is the application as an abrasion or oxidation protection layer to correspondingly protected, not necessarily planar substrates.

Advantageously, the starting materials used are thermoplastic polymers, such as polyacrylates, polyurethanes, polyethylenes and copolymers thereof. The polymer used can be present before application to the corresponding substrate as a dispersion or solution in a liquid medium. In addition, mixtures of the aforementioned polymers can be used.

Advantageously, the ceramicizable bonding layers are matched in their material composition to the ceramic of the layers to be joined.

The invention makes it possible to produce a firm, permanent cohesion between individual ceramized layers. The invention also makes it possible to adapt the properties of the filling layer to the properties of the material of the ceramic layers to be bonded by appropriate choice of the composition of the filling material.

The laminates so produced are then converted into ceramic by a thermal treatment, with both the layers of material and the intermediate layers provided by the invention being converted into ceramics.

In addition, the bonding layers can be easily applied to planar precursors, which can then be laminated.

As filler particles here preferably metals / semimetals of II. To IV. Main group, the subgroups including lanthanides and their alloys, and their crystalline and amorphous compounds are used with non-metals of the second period (excluding fluorine and neon) of the Periodic Table of the Elements.

Also usable as filler particles are mixtures and mixed compounds of these substances, such as aluminosilicates, glasses, and the like,

The filler particles of the bonding layer can be matched to the type of ceramic to be created, in the case of oxidic ceramic oxide, in the case of carbide ceramics carbide filler particles can be used.

In addition, when mixing the adhesive layer forming the bonding layer, process aids such as dispersants and defoamers may be added, advantageously in the range from 0 to 2% by weight in each case.

The bonding layer can be applied to the substrate to be coated with all technologies used in the coating technology, such. As screen printing, pad printing or spraying. For example, paper webs can be coated by brushing, technologies such as powder spreading and subsequent fusing can also be used. The achieved layer thicknesses are preferably in the range of 1 to 500 microns.

After the substrate has been coated with the adhesive, substrates can be laminated, the adhesive being heated briefly above the glass transition temperature of the polymer or the adhesive and the substrates being joined together without pressure or pressure, so that the surfaces of the material layers can come into contact with one another. By solidification of the adhesive during cooling, the substrate layers are permanently connected. The result is a laminate which has an alternating sequence of material layer and connecting layer. Such a laminate is characterized by at least two layers of material and at least one bonding layer.

In a subsequent temperature treatment, the bonding layer is thermally treated, wherein the temperature treatment is carried out until the polymer used no change in mass, determined by thermogravimetric analysis, learns more, depending on the polymer and atmosphere polymer residues in the range of 0 to 75% by mass can.

The base polymer is either completely removed or, in the case of a temperature treatment under an inert gas atmosphere, converted into a carbon film. When using polysiloxanes as base polymer Si-OC are formed accordingly. When using polysilazanes as the base polymer, a Si-ON phase is formed accordingly. This is advantageous in temperature ranges of 200 - 1400 ⁰ C.

By a further temperature treatment, a ceramic intermediate layer is formed from the adhesive residue. Surface reactions take place between the pyrolysis residue, the filler particles and the substrate surfaces and combinations thereof. Advantageously, this temperature treatment takes place in temperature ranges in which the filler particles used have an increased surface reactivity. Typically, this occurs in temperature ranges between 1000 and 2000 ⁰ C.

Advantageously, both temperature treatments can be carried out in one step.

The invention is further characterized in that the thickness of the bonding layer can be changed by previous temperature treatments. Typical boundary layer thicknesses are in the range of 0.5 μm to 200 μm. While the bonding layers described are advantageously used to bond the preceramic papers or boards of the invention, it will be apparent to those skilled in the art that these bonding layers can be used to bond any ceramizable material.

Further details and features of the invention will become apparent from the following embodiments.

Embodiment 1

To prepare an aluminum oxide paper, the starting components used are firstly 15% by mass of eucalyptus sulphate pulp, based on the sheet material. 83% by mass, based on the leaf mass, of aluminum oxide powder having an average particle size diameter (D50) of 0.8 μm are added. Furthermore, anionic latex is admixed to 2% by mass, based on the leaf mass, and 0.7% by mass, based on the filler of a cationic polymer (Katio- fast VFH).

From this mixture, a circular laboratory sheet with a diameter of 20 cm and a basis weight of 380 g / m ^{2 is} produced.

In the experiment, 360 g of pulp suspension (0.5% strength) were admixed with 7 g of Katiofast (1% strength). Further, 19.92 g of alumina slurry (50%) was added. Finally, 6 g latex emulsion (4%) was added. From this mixture, a leaf was formed, which was then dried.

The resulting green body is shown in Figure 1 in section. This structure was then sintered. After sintering, the structure shown in FIG. 2 results.

Variants for embodiment 1: In a variant of the aforementioned embodiment, an aluminum oxide powder having an average particle size (D50) of 3.9 microns is added. In addition, a coating of an alumina powder-latex mixture with an average particle diameter (D50) of 0.8 microns is provided.

A corresponding sectional view through the green body formed here results from FIG. 3.

Variant 2 for the embodiment 1:

A further variant of the mixture results from the fact that a bimodal aluminum oxide powder mixture was used here, wherein on the one hand an average particle size (D50) of 0.8 .mu.m and on the other hand an average particle size (D50) of the order of 3.9 .mu.m was. The corresponding green body is shown in FIG.

Embodiment 2:

To produce a silicon carbide-filled paper, based on the leaf mass, 20% by mass of a eucalyptus sulfate pulp having 77% by mass of silicon carbide powder having an average particle size (D50) of 4.5 μm are mixed. It is mixed anionic latex to 3 mass% based on the leaf mass. Based on the filler, 0.9 mass% of a cationic polymer (Katiofast VFH) is now added.

From this mixture, a circular laboratory sheet is produced with a diameter of 20 cm and a basis weight of 320 g / m ² .

In the experiment, 400 g of a 0.5% pulp suspension with 7 g of 1% Katiofast were added in this embodiment. 7.7 g of silicon carbide powder were added and 7.5 g of 4% latex emulsion. The mixture became a leaf formed and the sheet was dried. The corresponding green body is shown in section in FIG. 5. After the corresponding pyrolysis, the sectional image corresponding to FIG. 6 results. Subsequently, a siliconization is carried out by further heat treatment. After the siliconization, the sectional image corresponding to FIG. 7 results.

8 shows a laminate ceramic 1 produced by the LOM method from substrate layers 3 and connecting layers 2. The LOM method makes it possible to create ceramic components in virtually any three-dimensional shape.

FIG. 9 shows a section through such a laminate ceramic with substrate layers 3 and connecting layers 2.

The following exemplary embodiments of the bonding layers according to the invention and the laminate ceramics according to the invention show an exemplary implementation of the invention.

Embodiment 3

100 g of a heat sealable, present in aqueous dispersion Kaschierklebstoffes polyacrylate are diluted with 40 ml of distilled water, 32 g of an Al ₂ O ₃ powder (d ₅₀ = 0.8 microns), 2 g of a dispersant and 1 g of a defoamer are stirred , The mass is homogenized in a PE vessel with grinding balls for 24 h and then evacuated. The mass is applied by brushing one side of a preceramic paper in a wet film thickness of 100 microns and dried in air. The applied adhesive film experiences a dry shrinkage of 60%. After drying, several layers of paper can be machine laminated at 180 ^° C. The organic components of the laminates are burned out in the temperature range from 350 to 800 ^° C. in air, the shaped body is then sintered at 1600 ^° C. for 2 hours in air. This process results in ceramic components whose microstructure Adhesion is shown in Fig. 9. After the temperature treatment, the adhesive has yielded a ceramic layer with a thickness of about 10 μm and permanently bonds the material layers.

Embodiment 4

10Og of a Polymethylsilseqiuoxanes, 20g of a novolak phenolic resin and 10 g of a fumed silica are dry mixed and homogenized in a PE vessel with grinding balls for 24 h. The powder mixture is then sprinkled onto a surface of preceramic paper layers and fused at 90 ^° C. for 15 minutes. Multiple paper layers can be machine laminated at 140 ° C. After pyrolysis under nitrogen atmosphere at 800 ⁰ C and subsequent liquid-sigphasensilizierung at 1500 ° C under vacuum components are obtained.

One possible cardboard structure is corrugated cardboard. As a result of the method according to the invention, it is also possible here to realize corrugated cardboard with small waves.

By selecting appropriate fillers and appropriate application of pyrolysis and sintering steps, microstructure and properties can be adjusted specifically.

In addition, subsequent infiltration with glasses, metal or polymer melts can be applied to the ceramic composite body.

The inventively presented paper-filler system allows the transfer to rapid prototyping process.

The papers can also be processed into laminates by so-called Laminated Object Manufacturing (LOM).

The linear shrinkage of the paper is usually between 10 and 20% depending on the type of filler. The variation of the filler load of the paper leads to the ex- plicit adjustability of process-determining material parameters, such as cuttability, shape or structure gradients. As a result, the properties of the ceramics produced from the preceramic paper or from the preceramic paperboard can be varied within a wide range.

Claims

claims

1. Ceramic of preceramic paper or cardboard structures in a specific shape, previously shown in a paper structure,

characterized,

that the preceramic papers or boards have a content of ceramic fillers between 30 and 95 mass%, wherein the ceramic fillers have a particle size <30 microns.

2. Ceramic according to claim 1, characterized in that it is designed in the form of a previously illustrated paper or cardboard structure as a composite ceramic.

3. Ceramic according to claim 1 or 2, characterized in that the fillers are selected from a group of the following substances: carbides, nitrides, oxides, borides and / or zeolites.

4. ceramic according to claim 3, characterized in that as fillers Al2O3, ZrO ₂ , SiC, Si ₃ N ₄ , TiO ₂ , B ₄ C, TiC, TiB ₂ and / or mixtures thereof and / or glasses are used as aluminosilicates.

5. Ceramic according to one of the preceding claims, characterized in that in the preceramic paper or in the preceramic cardboard for the retention of the fillers latex loaded or charged starch are contained in combination with a charged polymer.

6. Ceramic according to one of the preceding claims, characterized in that the proportion of latex in the preceramic paper or in the preceramic cardboard is between 0.2 and 15% by mass.

7. Ceramic according to one of the preceding claims, characterized in that the proportion of polymer in the preceramic paper or in the preceramic cardboard is between 0.05 and 5% by mass.

8. Ceramic according to one of the preceding claims, characterized in that long or short ceramic fibers, fiber fabrics, platelets and / or whiskers are added as reinforcing elements.

9. Ceramic according to one of the preceding claims, characterized in that are used as fibrous Suifatzellstoff, sulfite pulp, TMP and / or CTMP.

10. Ceramic according to one of the preceding claims, characterized in that the thickness of the preceramic paper and / or cardboard structure is in the range of 50 to 500 microns.

11. Ceramic according to one of the preceding claims, characterized in that the weight of the preceramic paper and / or cardboard structure is in the range of 100 to 500 g / m ² .

12. Ceramic according to one of the preceding claims, characterized in that the ceramic is infiltrated with glasses, metal or polymer melts.

13. Ceramic according to one of the preceding claims, characterized by

Tie layers based on either room temperature solid thermoplastic polymers or silicone / phenolic resins below their cure temperature.

14. The ceramic of claim 13, wherein the polymers include polyacrylates, polyurethanes,

Polyolefins, and their copolymers include.

15. The ceramic of claim 13, wherein the compound layer contains filler particles whose content is up to 90% by mass, wherein the filler particles have mean particle sizes less than 50 microns.

16. The ceramic of claim 15, wherein as filler particles metals / semimetals of II. To IV. Main group, the subgroups including lanthanides and their alloys, and their crystalline and amorphous compounds with non-metals of the second period (excluding fluorine and neon) of the Periodic Table of the Elements be used.

17. ceramic according to claim 16, wherein mixtures and mixed compounds of the substances used there, such as aluminosilicates, glasses, and the like can be used as filler particles.

18. Ceramic according to claim 15, wherein the homogeneous distribution of the filler particles by means of appropriate processing aids such as dispersants and defoamers in levels of 0 to 2 mass% is improved.

19. ceramic according to claim 13, wherein the connecting layer by means of conventional

Coating technologies in layer thicknesses of 1 to 500 microns is applied to the substrate to be joined, which can be converted by appropriate temperature treatment in ceramics.

20. The ceramic of claim 13, wherein the bonding layer according to the preceding claims is briefly heated over T _{m of} the polymers and permanently bonds after their solidification.

21. The ceramic of claim 13, wherein the bonding layer is present after a Lami- niervorgang between individual substrate layers, resulting in an alternating material structure.

22. The ceramic of claim 21, wherein the substrate layers of preceramic

Paper or preceramic cardboard.

23. The ceramic of claim 21, wherein the laminate ceramic by at least two

Material layers and at least one tie layer is characterized.

24. The ceramic of claim 13, wherein the polymers in a subsequent

Temperature treatment, advantageously between 200 and 1400 ⁰ C, are thermally decomposed; the treatment is carried out until, during the temperature treatment, there is no longer any change in mass, irrespective of the polymer used, the atmosphere and the residue obtained.

25. The ceramic of claim 15, wherein the compound layer is converted by a temperature treatment under an air or inert atmosphere in a ceramic intermediate layer, wherein surface reactions between Polymer residuum, filler particles, substrate surfaces and combinations thereof take place.

26. The ceramic of claim 25, wherein the temperature treatment takes place in temperature ranges in which the filler particles used have an increased surface reactivity, typically in the range of 1000 - 2000 ⁰ C.

27. Ceramic according to claim 13, wherein the temperature treatments according to claims 24 - 26 are carried out in one step.

28. The ceramic of claim 13, wherein the thickness of the bonding layer through the

Temperature treatments can be varied, typically in the range of 0.5 to 200 microns.

29. The ceramic of claim 13, wherein the bonding layer is applied as protection against atmospheric or chemical attack on a substrate.

30. The ceramic of claim 13, wherein the bonding layer is applied as a protective layer against mechanical action on a substrate.

31. A method for producing a ceramic according to any one of the preceding claims, characterized by the following steps:

Pulp and filler are mixed and processed into a paper or a cardboard,

the paper produced or the paperboard produced is a pyrolysis or a debinding at temperatures up to 1200 ° C and / or a sintering process at temperatures between 1000 ⁰ C and 2000 ° C exposed.

32. The method according to claim 31, characterized in that before the pyrolysis step, the base paper or the produced raw board is subjected to a molding step, for example, a corrugating or corrugated board production.

33. The method according to any one of the preceding claims, characterized in that individual layers of papers or paperboards are vergautscht to obtain thicker layers.

34. The method according to any one of the preceding claims, characterized in that differently constructed ceramic paper or paperboard be vergautscht together.

35. The method according to any one of the preceding claims, characterized in that on the paper or the cardboard ceramic slip is applied by means of paper coating.

36. The method according to claim 35, characterized in that different ceramic slurry layers are spread onto the paper or the cardboard such that a multilayer system results.

37. The method according to any preceding claim, characterized in that layers in the green or sintered state are applied by means of sol-gel technology.

38. The method according to any one of the preceding claims, characterized in that an infiltration with glasses, metal or polymer melts is applied in the ceramic

39. The method according to any one of the preceding claims, characterized in that a plurality of layers of the paper or the paperboard produced are connected by connecting layers.

40. Use of a ceramic according to one of claims 1 to 30 as a ceramic membrane for gas separation or liquid filtration.

41. Use of a ceramic according to one of the preceding claims as a pore burner.

42. Use of a ceramic according to one of claims 1 to 12, as a thin-walled and dense construction ceramics.