DE102010055248B4 - Method and device for producing a ceramic composite material - Google Patents

Abstract

A method of making a ceramic composite (64) comprising the steps of a) providing ceramic fibers (10) with a1) coating the ceramic fibers (10) with a liquid; b) braiding the ceramic fibers (10); and c) infiltrating the ceramic fibers (10) with a matrix material (40) suitable for forming an oxide ceramic.

Description

The invention relates to a method and an apparatus for producing a ceramic composite material.

In fiber-reinforced ceramic composite materials, ceramic fibers are preferably embedded in preferably ceramic matrix systems so as to achieve a bond between the ceramic fibers and the respective matrix material.

The only commercially available braiding tools made of oxide ceramic fibers are the Nextel braided sleeving ^TM from 3M (3M Nextel Ceramic Textiles and Materials, Nextel-Brochure, 2009).

Gries, T., Stueve, J. Grundmann, T., Textile Reinforcement Structures, Ceramic Matrix Composites, Wiley-VCH, 2008 describes that 3D braids are overwound with Nextel ^™ 720 fibers and used as hot gas filters.

In Mello, M.D., Florentine, R.A., 3D braided, continuous Fiber ceramic matrix composites produced by chemical vapor infiltration, SBIR report, US Army Research Laboratory, 1993, it is described that three-dimensional braids have been developed for ballistic applications.

For the thermal protection concept of the European space transporter Hermes planned in the 1980s, ceramic tiles were to be sealed against each other by oxide-ceramic cushions (Nemoz, G., Dogigli, M., High-temperature static seals for space vehicles, Proc. Conference on Spacecraft Structures, Materials and Mechanical Testing, 1996).

In the patent US 4,928,645 A It is disclosed that a part of valves for internal combustion engines is to be made of Nextel ^™ braided sleeving in combination with short fiber reinforced ceramic.

In the patent US Pat. No. 6,345,598 B1 a Handflechtverfahren is described for the preparation of Ventilpreformen.

Nicalon and Hi-Nicalon SiC fibers, according to Sharp, K. et al., Show high modulus fibers in 3D woven and braided CMC preforms, 37 ^th Int. SAMPE Technical Conference, 2005 showed better textile processability than Nextel ^™ 720 fibers.

In fiber composites, fiber preforms are generally impregnated with a variety of infiltration processes.

A first method is the RTM process (Resin Transfer Molding), in which a fiber preform is introduced into a two-sided, mostly heated mold with release agent, and then the mold is closed and evacuated. Matrix material and hardener are mixed externally and then injected under pressure into the mold. In the mold, the component is cured and then removed from the mold. The relatively easy monitoring of the process parameters and the automated impregnation of the fibers allows the production of high-quality components with constant quality, high fiber volume content and smooth surfaces on both sides of the mold. However, the production of complex shaped components is difficult and the process involves high tooling costs. This process is described, for example, in Berenberg, B., Resin transfer molding and preforms for jet engine stators, High-Performance Composites, 2004.

In the VARTM process (English: Vacuum Assisted Resin Transfer Molding), only a one-sided mold is used and the contact pressure is achieved by applying a vacuum under a vacuum film and the air pressure from the outside. Therefore, the negative form need not be as stable as the RTM method. In particular, large-area components can be produced; The VARTM process brings significantly lower tooling costs than the RTM process. For example, this method is described in Cunningham, G., JASSM composite body programs saves millions, Leading Edge, 2002.

In the VAP process (English: Vacuum Assisted Process, described in the DE 100 13 409 C1 ), the fiber preform is provided with flow aids, covered with an air-permeable and impermeable to matrix material membrane and provided with a feed for the matrix material. A nonwoven is placed over it to achieve a uniform vacuum, the structure is covered with a vacuum film and equipped with a connection for the vacuum pump. At the beginning of the process, the air is drawn off under the vacuum film and from the preform, then the feed for the already mixed matrix material-hardener mixture is opened and flows into the preform. The membrane allows uniform wicking of the matrix material as well as large area degassing of the matrix material allowing for high quality, nonporous laminates with high fiber volume fraction. It is only a one-sided tool necessary, resulting in lower tooling costs than the RTM method. Preferably, the film-side surface is post-processed.

If fiber-reinforced composite materials are to be mass-produced as semi-finished products with a constant cross-section, this is preferred Pultrusion method applied. The fibers are withdrawn from coils on which they are wound, then impregnated, for example, in an impregnating bath with matrix material and fed into a heated nozzle. There they are compacted, so that the matrix material is distributed between the filaments and a defined fiber volume fraction results. During the subsequent thermal curing, the desired cross-sectional shape is fixed.

DE 109 44 345 A1 discloses a manufacturing method for making a fiber reinforced ceramic matrix composite in which ceramic fibers are entangled and the resulting web is infiltrated with a matrix material from which a ceramic matrix is formed by high temperature treatment.

In DE 696 07 056 T2 For example, a process for making a fiber reinforced ceramic composite is described in which oxide ceramic fibers are entangled and then infiltrated with a matrix material from which an oxide ceramic can be formed. The ceramic fibers are coated with a sliding layer or a barrier layer made of a solid material prior to interlacing and infiltration via evaporation.

DE 42 24 779 A1 describes a method for producing a ceramic composite in which ceramic fibers are wound around a winding core and then infiltrated with a sol from which an oxide ceramic can be formed.

The object of the invention is to propose a method for producing a ceramic composite material, which leads to a particularly advantageous ceramic composite material. In particular, the method should be qualitatively more accurate, faster and less expensive compared to previously customary production methods.

The object is achieved by a method having the features of claim 1. An apparatus for producing ceramic composite materials is the subject of the independent claim.

Advantageous embodiments of the invention are the subject of the dependent claims.

• a) Bereitstellen von Keramikfasern mit a1) Beschichten der Keramikfasern mit einer Flüssigkeit;
• b) Flechten der Keramikfasern; und
• c) Infiltrieren der Keramikfasern mit einem zum Bilden einer Oxidkeramik geeigneten Matrixmaterial.

A method for producing a ceramic composite comprises the following steps:

• a) providing ceramic fibers with a1) coating the ceramic fibers with a liquid;
• b) braiding the ceramic fibers; and
• c) infiltrating the ceramic fibers with a matrix material suitable for forming an oxide ceramic.

Steps b) and c) may be performed in any order or simultaneously.

Conventional methods of making ceramic composites are more time consuming and costly than a method of braiding ceramic composites. Furthermore, a better reproducibility of the braids produced and a more complicated geometry of the components can be achieved by means of the braiding technique.

To infiltrate the ceramic fibers, the following routes can be chosen:
In the so-called PIP process (English: Polymer Infiltration and Pyrolysis), the ceramic fibers are guided, for example, by means of impregnating rollers or impregnating baths in order to wet them with a so-called slip as matrix material. Alternatively, a dry braided or otherwise prepared fiber preform may be infiltrated with a preceramic slurry via vacuum and / or pressure assist. The slip comprises, for example, a not yet cross-linked preceramic polymer and optionally ceramic fillers, wherein preferably the preceramic polymer is later converted by pyrolysis to ceramic.

In the so-called LPI (Liquid Polymer Infiltration) process, the ceramic fibers processed into prepregs in planar structures, for example plates or in complex component-like structures, are pressed in an autoclave to crosslink the polymer and to draw air out of the body. Alternatively, a sol-gel slip may also be used here, whereby preferably an autoclaving step may be omitted. Subsequently, the polymer or the preceramic matrix material is pyrolyzed in the sintering furnace under protective gas and thereby converted into ceramic. When using a pure oxide ceramic matrix can be dispensed with a protective gas atmosphere and the sintering can preferably be carried out with air contact. By increasing the density and the associated shrinkage of the matrix material, a porosity is produced, which is reduced by post-infiltration of preceramic polymers and subsequent repeated pyrolysis. By means of several infiltrations, ceramic composite materials, so-called CMCs, can be produced with very low residual porosity.

Alternatively, the sol-gel technology can be used in which, instead of a preceramic polymer ceramic particles in a stable colloidal solution, a so-called sol, are used. The sol as a matrix may also be incorporated into the fibers by impregnating baths or other infiltration techniques such as rolling, brushing or spraying. It is, for example, by changing the pH or gelled by freezing, dried and then sintered to form a ceramic, porous matrix.

Also, by applying an electric field, ceramic particles that are in a colloidal solution can be deposited on the fibers. This process is called electrophoretic infiltration (EPI). The interstices of the fibers are filled with the ceramic particles. Dry and finished Faserpreformen are advantageously used in the EPI process, which are introduced into an electric field. After drying, the infiltrated component is sintered without pressure. In order to apply an electric field, the ceramic fibers should preferably be rendered conductive by applying a surface charge. This can be done by adding additives. Thanks to the EPI process, even deep pores can be evenly filled with particles. For this, the colloidal solution should preferably be kept in motion so as to keep constant the concentration of the particles in the solution. Furthermore, the particles should preferably be small enough to be able to penetrate into the spaces between the fibers. To prevent agglomeration, the particles should preferably repel each other and from the fibers through the applied surface charge.

Furthermore, the following methods for the infiltration of ceramic fibers with matrix material can also be used:
When rolling in matrix material, the braided fibers are introduced into immersion baths, immersion baths under vacuum or immersion baths in ultrasound with matrix material. Then the matrix material is manually rolled by hand with a rubber roller. Thus, the ceramic particles are distributed into the smallest interstices of the fibers. Subsequently, the impregnated fibers are stacked layer by layer and hot pressed.

• • Der Partikeldurchmesser sollten kleiner sein als 0,05 mal der Durchmesser der Fasern.
• • Die Partikel des Matrixmaterials sollten sich gegenseitig abstoßen.
• • Es sollten abstoßende Kräfte zwischen Partikeln und Fasern vorliegen.

The PI process (Pressure Infiltration) uses a slurry, ie matrix material of water and mullite particles, in which the braided fibers are immersed. Then they are put together in a pile. This stack is placed in a precisely fitting shape, wherein the bottom of the mold is constructed of a perforated steel plate and is provided with a filter paper, which does not let particles through. From the top slip is filled and applied with a stamp a pressure. Once the fibers have been completely infiltrated, the component is removed, dried and sintered without pressure. If necessary, it is post-infiltrated to achieve maximum tensile strength at room temperature. For a successful PI procedure, the following parameters should preferably be adhered to:

• The particle diameter should be less than 0.05 times the diameter of the fibers.
• • The particles of the matrix material should repel each other.
• • There should be repulsive forces between particles and fibers.

The actual infiltration can be supported by applying a vacuum and the resulting pressure gradient. Rapid infiltration can be accelerated by the application of vibration (vibrointrusion) as it makes it easier for the particles to repel one another and make the mass flowable.

The ceramic fibers can be impregnated at various stages of processing by the above methods.

The first conceivable possibility of introducing matrix material into the fibers is the impregnation of each individual roving before it is deposited on the braided core. This can be done by using prepreg rovings or on the way from the bobbin to the core. The prepreg rovings can be soaked in mattresses with matrix material just before winding the rovings onto the bobbins. Furthermore, the matrix material can be sprayed onto the fibers on the way from the bobbin thread to the batt ring. The matrix material is infiltrated by the deflection at the braiding ring and the final compression of the composite in the spaces between the fibers.

A second way to introduce matrix material into the fibers is to apply matrix material to the fibers after each braided layer during the braiding process. The matrix material can be rolled up manually, brushed on or sprayed on.

As a third option, all braided fibers can be impregnated with matrix material at the same time. This can be supported by a combination of the VAP method with the PI method. In this case, a colloidal solution is sucked in on one side of the preform and flows through it. At the other end of the preform is a semipermeable membrane which allows the solvent to pass but retains the particles therein. As a result, the particles accumulate counter to the direction of infiltration and fill the preform. When the preform is completely filled, the excess solvent is dried out.

Preferably, oxide ceramic fibers are provided in step a). Depending on the field of application, oxide-ceramic fibers have the advantage, in comparison to, for example, carbon fibers or silicon carbide, that they are particularly effective in an oxidative atmosphere a better temperature resistance have a longer life.

The oxide ceramic fibers preferably comprise an oxide ceramic material or are composed of the pure oxide ceramic material selected from a group containing Al ₂ O ₃ , mullite, SiO ₂ and / or B ₂ O ₃ . Such oxide ceramic materials as well as the respective oxide ceramic fibers are available on the market, whereby the manufacturing costs of the ceramic composite materials are preferably lowered.

Step a) comprises step a1) coating or coating the ceramic fibers. By etching the ceramic fibers are protected. In most cases, a size contains, among other things, polyvinyl alcohol (PVA) and additives which protect the ceramic fibers during winding on spools and during subsequent braiding, d. H. facilitate, improve and / or make possible the textile processability of the ceramic fibers. By coating, the ceramic fibers are prepared for braiding, for example, made supple. In addition, it is also possible to use various fiber coatings which weaken or "adjust" the fiber-matrix connection, in particular in the case of a dense matrix, and thus enable damage-tolerant material behavior.

On the one hand, a Fugitive Coating can be applied, which is burned away before the use of the finished component and thus leaves a gap between the ceramic fibers and the matrix. Matrix cracks can not be passed through and run along the fiber. Suitable coating materials here are, for example, phenolic resins which are converted to carbon with the exclusion of oxygen and finally outgas in the oxidative aging process as carbon dioxide.

On the other hand, it is also possible to apply weak oxide layers with lower strengths than those of the matrix and with plastic deformability. They derive matrix cracks parallel to the fibers. For example, monazites (LaPO ₄ ) or other phosphates can be used here. In addition, by applying a porous layer on the ceramic fibers targeted the fiber-matrix connection can be weakened. Zirconium oxide (ZrO ₂ ) and compounds of rare earth metals or aluminum are suitable for this purpose.

Preferably, the ceramic fibers are coated in step a1) with a lubricant. As a result, the ceramic fibers are supple and can be braided on a braid core with less probability of breakage. As a lubricant, for example, water, oils or glycerol can be used. However, all liquids are conceivable which make the ceramic fiber so pliable that it can be braided with a lower probability of breakage on a braided core, for example polypropylene or polyvinyl alcohol.

• • Polymer
• • Füllstoff
• • Lösungsmittel.

In a preferred embodiment, the ceramic fibers are infiltrated with a sol or a suspension as matrix material in step c). In this case, the suspension preferably has at least one of the following ingredients:

• • Polymer
• • filler
• • solvents.

The sol is a mostly water-based colloidal dispersion that spreads well over the ceramic fibers. By appropriate steps, the sol is consolidated into a gel from which an oxide ceramic can be obtained in further steps.

The ceramic fibers may also preferably be infiltrated with a suspension whose ingredients can be varied, thereby adapting to both the ceramic fiber used and the requirements of the component being manufactured. Depending on the application, various polymers, fillers and solvents can be used for this purpose.

Preferably, a preceramic polymer is used, from which a ceramic can be obtained by appropriate treatment. Preferably, a polymer is used from which an oxide ceramic can be obtained. Thereby, a ceramic composite can be produced in which the reinforcing fibers and the matrix have similar properties.

Particularly preferably, a flowable polymer is used. Both powdered, solvent-incorporated polymers and liquid polymers are suitable for this purpose. The fluidity of the polymer is advantageous for uniformly incorporating the polymer into the interstices of the ceramic fibers by the methods described above.

Advantageously, an active or passive filler, in particular a ceramic filler, is used in the polymer as filler. Active fillers themselves become a ceramic material during post-treatment, while passive fillers only fill up the resulting pores. Depending on the process and the desired pore depth, a suitable filler can thus be used.

Preferably, after step c), a step d) is followed by high-temperature treatment of the braided ceramic fibers infiltrated with matrix material. By the High-temperature treatment is made of the matrix material, a ceramic, in particular an oxide ceramic. Depending on the matrix material is spoken of pyrolysis or sintering. Pyrolysis means that, for example, a polymer decomposes during high-temperature treatment and reacts to form an inorganic oxide ceramic. When sintering is usually, but not necessarily, under pressure in granular form matrix material interconnected.

• • Trocknung;
• • Aushärtung;
• • Chemische Reaktion; und/oder
• • Gefrieren

durchgeführt.It is advantageous before step d) at least one of the steps

• • drying;
• • curing;
• • Chemical reaction; and or
• • Freeze

carried out.

Through a chemical reaction, a polymer material applied / infiltrated matrix material can advantageously crosslink, so as to later form an oxide ceramic layer between the ceramic fibers. If the polymer is dissolved in a solvent, it is preferably first cured before step d) by removing the solvent, for example by heating. For example, a matrix material applied as sol consolidates or gels irreversibly to a gel upon freezing or by changing the pH, and is then preferably desized from water in a drying oven, i. H. it is dried. Thus, ceramic fibers infiltrated with either sol or polymer as matrix material are prepared for the high temperature treatment to form the oxide ceramics.

In a particularly preferred embodiment, after the high-temperature treatment, further infiltration steps, so-called post-infiltration, follow, in order to fill up the resulting pores in the matrix.

An apparatus for producing ceramic composite materials comprises a fiber preparation device for weaving ceramic fibers, a braiding device for braiding ceramic fibers and an infiltration device for infiltrating the ceramic fibers with a matrix material suitable for forming a ceramic matrix, in particular an oxide ceramic matrix.

Thus, the ceramic fibers can first advantageously be prepared for braiding in the fiber preparation device by, for example, first being rewound by means of a rewinding device and / or rendered supple in a coating device by, for example, applying a lubricant.

The braiding device preferably has a fiber guiding system and / or a braiding core and / or a handling device, in particular a robot arm, and / or the braiding device is designed for braiding oxide ceramic fibers. Then, the fiber guide system should preferably be designed so that the oxide ceramic fibers are subjected to the least possible deflecting forces and changes in radius and are not damaged, for example, break.

The device preferably has a heating device and / or a cooling device. Thus, the ceramic fibers impregnated with matrix material can be dried, hardened, frozen and pyrolyzed or sintered.

With the device, it is possible to braid ceramic fibers and then infiltrated with a matrix material. By braiding different geometries of a component can be produced and also costs can be saved over conventional methods.

Embodiments of the invention will be explained in more detail with reference to the accompanying drawings. It shows:

1 the preparation of a ceramic fiber for braiding;

2 braiding the ceramic fiber on a braided core;

4 a first infiltration embodiment for infiltrating the braided ceramic fibers;

5 all steps for the production of ceramic composite materials with the infiltration process according to the first embodiment;

6 a second embodiment for infiltrating the braided ceramic fibers;

7 a second step in the infiltration of the ceramic fibers according to the second embodiment; and

8th all process steps for the production of ceramic composite materials with the infiltration process according to the second embodiment.

1 shows steps to prepare a ceramic fiber 10 braiding in a fiber preparation facility 12 be performed.

The fiber preparation device 12 has a desizing device 14 , one coater 16 and a rewinding device 18 on.

The ceramic fiber 10 is commercially available, for example 3M Nextel ^™ 610 fiber, and is coated with a size on a first spool by the manufacturer 20 delivered. Nextel ^™ 610 ceramic fibers are oxide ceramic fibers 11 and have high mechanical strength and stiffness and are at the same time very temperature and oxidation stable. In a first step, the size is in the desizing device 14 removed by burning down. In a further step, in the coating apparatus 16 on the desized ceramic fiber 10 a layer of a lubricant 22 about roles 24 applied. The lubricant 22 can depending on the desired application a polar lubricant 22 , such as water or glycerol, or a nonpolar lubricant 22 , such as sunflower oil. There is just so much lubricant 22 on the ceramic fiber 10 applied that to the ceramic fiber 10 is completely wetted. After coating with the lubricant 22 becomes the ceramic fiber 10 in the rewinding device 18 on a second spool 26 wound, ie it becomes relative to the first coil 20 rewound.

A variety of these second coils 26 be in an in 2 shown braiding device 28 attached. The lichen device 28 has a fiber guide system 30 , a wickerwork core 32 and a handling device 34 for the wickerwork core 32 on. The handling device 34 is here by a robotic arm 36 made available. The robot arm 36 Holds the braid core 32 and guides it relative to the fiber guiding system 30 so that the ceramic fibers 10 to a braid 38 on the wickerwork core 32 be filed.

For this purpose, two possible embodiments are described below:
In a first embodiment, shown in the 4 and 5 , becomes the matrix material 40 with the VAP process in the braid 38 , this is a preform 43 forms introduced. It will do this with the braiding device 28 made braid 38 previously from the braiding facility 28 has been detached on a mold 44 stored. On the surface of the braid 38 becomes a flow aid 46 arranged and around the braid 38 and the flow aid 46 a gas-permeable, matrix-impermeable membrane 48 placed. This one comes with sealing strips 49 sealed so that at the sealing points neither matrix material 40 still gas can escape. About the membrane 48 becomes a vacuum fleece 50 placed and the whole construction by a vacuum foil 52 enclosed. The vacuum film 52 is neither permeable to gases nor to matrix material 40 and is also covered by sealing strips 49 sealed. The vacuum film 52 is through a vacuum line 54 broken in between the membrane 48 and the vacuum film 52 formed first room 56 that sticks out.

Both vacuum foil 52 as well as membrane 48 be through a lead 58 for matrix material 40 broken, so the line 58 in the under the membrane 48 formed second room 60 that sticks out. When infiltrating the braid 38 will now be through the line 58 matrix material 40 in the form of a preceramic polymer 62 , for example, polysiloxane, in the second space 60 brought in. About the vacuum line 54 In the interior of the structure, a vacuum is generated, which flows over the vacuum fleece 50 over the entire first room 56 is distributed. The resulting negative pressure becomes matrix material 40 in the second room 60 sucked in and through the flow aid 46 over the network 38 distributed. At the same time, the braid becomes 38 freed from air or other gases. Because the membrane 48 permeable to gases, but not for matrix material 40 Also, there is no danger of the vacuum line 54 through matrix material 40 is contaminated.

In 5 are all steps to making a ceramic composite 64 shown by the VAP method. The with matrix material 40 in the infiltration device 42 infiltrated network 38 gets into a heater 66 transferred where the preceramic polymer 62 hardens and crosslinks. Thereafter, the hardened braid 38 in a high temperature oven 68 transferred where it is pyrolyzed, so that the preceramic polymer 62 to a ceramics 70 implements. Thus, the ceramic composite is 64 emerged. Because in this material 64 a large number of pores is present, further infiltration steps, curing steps and high temperature steps are needed if necessary to fill the pores and better strength properties of the ceramic composite 64 to achieve.

In a second embodiment of the infiltration device 42 for infiltrating the ceramic fibers 10 with matrix material 40 first becomes a first location 72 of the braid 38 on the wickerwork core 32 been platted. This location 72 is over a squeegee 74 with a sol 76 infiltrated. As in 7 is shown on the first position 72 a second location 78 braided and again with the squeegee 74 with the sol 76 infiltrated. This is done until the desired thickness of the component is achieved. After detachment of the braid 38 from the braided core 32 becomes the mesh 38 , as in 8th shown in a cooling device 80 brought in. The sol consolidates here to the gel, ie it gels. After thawing and removing water in a drying cabinet (not shown), the gel in the high temperature oven 68 to the ceramics 70 sintered.

Nextel ^™ 610 fibers are oxide ceramic fibers 10 that are oxidative in oxidic matrix Application atmosphere to achieve a longer life than ordinary ceramic fibers 10 ,

Fiber-reinforced oxide ceramics (oxidic CMC) are only produced via the standard routes for the production of CMCs, ie via the infiltration process by means of winding technology, PIP process or hand lamination of finished fabrics and subsequent sintering. The use of alternative textile technology for the production of fiber preforms 43 or CMCs, such as the braiding technique, has been a problem since it is difficult to use oxide ceramic fibers 10 to braid and especially in connection with this braiding technique to produce oxide fiber reinforced oxide ceramic.

Therefore, with the proposed method, an oxidic CMC material by means of braided technically processed oxide ceramic fibers 10 produced. The lichen device 28 and their components, such as the fiber guiding systems 30 , as well as the oxide ceramic fibers 10 are refined so that a damage-free textile processability is greatly improved and thus possible. An infiltration of fiber-fabricated fiber preforms 43 (Braids) with different, preferably sol-gel-based ceramic matrix systems 40 is thus possible. Thus, the production of oxide ceramic CMC bonds with oxide ceramic fibers 10 realized.

Oxide ceramic continuous fibers 10 different types, such as Nextel ^™ 610, braided without damage to braids 38 processed different fiber architecture, ie, among other things, different fiber orientations, angle, number of layers can be achieved. Related to this are the fiber preforms 43 with different oxide ceramic matrix systems 40 impregnated and other processing steps, such as drying, freezing, curing, sintering, etc., to oxide-ceramic composites 64 processed. This can be done via braiding technique and corresponding routes for the construction of oxide ceramic matrices 40 oxide ceramic CMC are produced. The braiding technique offers advantages in the production of oxide ceramic structures in terms of geometry diversity, time, cost, number, reproducibility, etc.

In principle, two different matrix systems are distinguished from each other, in which ceramic fibers 10 can be embedded: dense matrix 40 and porous matrix 40 ,

In the dense matrix 40 Matrix materials are used which have similar thermal expansions as the ceramic fibers used 10 have to prevent thermal stresses during the manufacturing process as well as in subsequent use. Also, if possible, creep resistance and mechanical properties should be comparable to those of ceramic fibers 10 be. To a forwarding of matrix cracks in the fibers 10 For example, despite the similar properties, fiber coatings, so-called interfaces or interface regions, can be used to weaken the fiber-matrix connection. Spreading cracks in the matrix 40 thus generate no voltage peaks when hitting fibers 10 , The energy dissipation occurs by growing matrix cracks, deflecting cracks along the fiber coating, and finally pulling out the fibers. When pulling out the fiber 10 From the dense matrix material, the fiber coating then acts like a sliding layer. The matrix material 40 becomes ceramics, for example, by pyrolysis 70 transformed and shrinking. By adding ceramic fillers, the shrinkage can be reduced, thus reducing the resulting porosity. The mechanical strengths of ceramic composites 64 with dense matrix 40 are relatively high.

A porous matrix 40 is inherently weak enough to avoid matrix cracks in the fibers 10 Therefore, a special fiber coating is not absolutely necessary. The energy dissipation is due to the spread of microcracks in the matrix 40 achieved, until complete pulverization of the matrix 40 enough. Advantageous for the porous matrix 40 is a finely divided but not too strong porosity to achieve good mechanical properties of the composite and yet achieve damage tolerance. Compared to ceramic composites 64 with dense matrices 40 are the interlaminar strengths of the porous matrix 40 less and the surfaces more susceptible to wear. Porous Matrices 40 However, they are much cheaper to produce than dense matrices 40 since no post infiltrations, ie further infiltration steps, are necessary.

LIST OF REFERENCE NUMBERS

10

ceramic fiber

11

Oxidkeramikfaser

12

Fiber preparation device

14

Entschlichtungseinrichtung

16

coater

18

rewinder

20

first coil

22

lubricant

24

role

26

second coil

28

braiding

30

Fiber Routing System

32

braid

34

handling device

36

robot arm

38

weave

40

matrix material

42

infiltration facility

43

preform

44

mold

46

flow aid

48

membrane

49

sealing strips

50

vacuum fleece

52

vacuum film

54

vacuum line

56

first room

58

management

60

second room

62

polymer

64

Ceramic composite material

66

heater

68

High-temperature furnace

70

ceramics

72

first location

74

doctor

76

Sol

78

second location

80

cooling device

Claims (13)

Method for producing a ceramic composite material ( 64 ) comprising the following steps: a) providing ceramic fibers ( 10 ) with a1) coating the ceramic fibers ( 10 ) with a liquid; b) braiding the ceramic fibers ( 10 ); and c) infiltrating the ceramic fibers ( 10 ) with a matrix material suitable for forming an oxide ceramic ( 40 ). A method according to claim 1, characterized in that in step a) oxide ceramic fibers ( 11 ) to be provided. A method according to claim 2, characterized in that the oxide ceramic fibers ( 11 ) comprise an oxide ceramic material selected from the group consisting of Al ₂ O ₃ , mullite, SiO ₂ and B ₂ O ₃ . Method according to one of the preceding claims, characterized in that in step a1) the ceramic fibers ( 10 ) with a lubricant ( 22 ) are coated. Method according to one of the preceding claims, characterized in that in step c) the ceramic fibers ( 10 ) with a sol ( 76 ) or a suspension as a matrix material ( 40 ), wherein the suspension comprises at least one of the following ingredients: polymer ( 62 ) • filler • solvent. Process according to claim 5, characterized in that a preceramic polymer ( 62 ) is used. Method according to one of claims 5 or 6, characterized in that a flowable polymer ( 62 ) is used. Method according to one of the preceding claims, characterized in that after step c) a step d) high-temperature treatment with the matrix material ( 40 ) infiltrated braided ceramic fibers ( 10 ) he follows. A method according to claim 8, characterized in that before step d) at least one of the steps • drying; • curing; • chemical reaction; and / or • freezing is performed. Device for producing ceramic composite materials ( 64 ) with a fiber preparation device ( 12 ) for weaving ceramic fibers ( 10 ), a braiding device ( 28 ) for braiding ceramic fibers ( 10 ) and an infiltration device ( 42 ) for infiltrating the ceramic fibers ( 10 ) with a matrix material suitable for forming a ceramic matrix ( 40 ), wherein the fiber preparation device ( 12 ) a coating device ( 16 ) for coating the ceramic fibers ( 10 ) with a liquid. Apparatus according to claim 10, characterized in that the fiber preparation device ( 12 ) a rewinding device ( 18 ) having. Device according to one of claims 10 or 11, characterized in that the braiding device ( 28 ) a fiber guiding system ( 30 ) and / or a wicker core ( 32 ) and / or a handling device ( 34 ), in particular a robot arm ( 36 ), and / or that the braiding device ( 28 ) for braiding oxide ceramic fibers ( 11 ) is trained. Device according to one of claims 10 to 12, characterized in that a heating device ( 66 ) and / or cooling device ( 80 ) is provided.

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