DE102019207617A1 - METHOD FOR MANUFACTURING A COMPONENT FROM A CERAMIC FIBER COMPOSITE MATERIAL - Google Patents

Abstract

The present invention relates to a method for producing components made of ceramic fiber composite materials, in which fibers (8) made of ceramic or carbon are embedded in a matrix (11) made of silicon carbide, layers (1, 3, 5) with an organic material (6 ) and silicon particles (7) and layers (2,4) with fibers (8) are arranged and shaped into a green body, the green body then being subjected to a heat treatment above the melting temperature of silicon, in which a SiC matrix (11 ) is formed in which the fibers (8) are embedded.

Description

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to a method for producing components made of ceramic fiber composite materials, in which fibers made of ceramic or carbon are embedded in a matrix made of silicon carbide.

STATE OF THE ART

Ceramic fiber composites, which are also known as Ceramic Matrix Composites CMC, are used in many areas of technology due to their good high temperature and corrosion resistance and their excellent mechanical properties, including high temperature applications in aircraft and aircraft engine construction. However, the production of components from ceramic fiber composite materials is difficult, since the absence of pores and homogeneity of the matrix are often difficult to achieve.

For example, in the production of components from silicon carbide reinforced with SiC fibers, the matrix is often produced by infiltration of liquid silicon into a fiber blank (preform). However, the penetration of the fiber blank with liquid silicon represents a difficulty which is more serious the larger the component is or the more SiC matrix has to be formed. This can mean that some of the carbon provided cannot react to form silicon carbide, so that the homogeneity of the matrix is impaired. In addition, pore formation can occur, which can also impair the use of components made of such ceramic fiber composite materials, such as fiber-reinforced silicon carbide.

In the document US 8 980 027 B2 For example, a method is described in which a fiber blank is mixed with powder particles which are then sintered to form the matrix or in which an additional, molten substance is added to form the matrix by infiltration. Here, too, the problem arises that if there is insufficient distribution of the powder particles and / or infiltration of the molten substance, the matrix can be made porous or inhomogeneous.

The document too US 9 440 888 B2 discloses a manufacturing process for a ceramic fiber composite material in which fibers coated with carbon are additionally mixed with carbon or ceramic powder in a fiber blank and molten silicon is infiltrated. Here, too, the infiltration of silicon can lead to the formation of pores or an inhomogeneous formation of the matrix.

In the US patent U.S. 5,589,115 A a method for producing a ceramic fiber composite material is described in which layers with fibers are arranged alternately with ceramic layers, which are then pressed at high temperature and pressure to form the fiber composite material. Although largely pore-free components can be produced here, the effort involved in pressing the ceramic layers with the fiber layers is high.

In the US patent U.S. 5,476,685 A a method for the production of a ceramic fiber composite material with carbon fibers which are embedded in a ceramic matrix is described, the matrix being produced by chemical vapor phase infiltration. But here too, in addition to the high expenditure for chemical vapor phase infiltration, the problem arises that the matrix can be inhomogeneous or pore formation can occur.

Also the US patent US 9 512 044 B2 describes the vapor phase infiltration of a fiber blank as a method for producing a ceramic fiber composite material. In addition, further infiltration processes for infiltrating various starting materials, such as, for example, polymers or other sludges or molten substances, are described, which, however, also lead to the problems described above.

The document too US 2016/0159066 A1 describes an infiltration method in which molten material is infiltrated into a fiber blank, with a porous ceramic layer additionally being formed on the fiber blank.

The US patent US 6,773,528 B2 describes in turn a method for producing a ceramic fiber composite material, in which ultimately molten silicon is infiltrated into a green body, which in turn brings with it the problems described above with regard to porosity and homogeneity of the matrix.

DISCLOSURE OF THE INVENTION

OBJECT OF THE INVENTION

It is therefore the object of the present invention to provide a method for the production of ceramic fiber composite materials or of components therefrom, in which the infiltration of corresponding substances into a Fiber blank or green body can be dispensed with and a homogeneous and largely pore-free matrix can be produced. In particular, a method is to be specified with which components made of fiber-reinforced silicon carbide can be manufactured in a reliable and simple manner.

TECHNICAL SOLUTION

This object is achieved by a method with the features of claim 1. Advantageous configurations are the subject of the dependent claims.

For the production of components from ceramic fiber composites based on silicon carbide, the invention proposes to form layers with an organic material and silicon particles as well as layers with fibers that are to be contained in the ceramic fiber composite material to form a green body, the green body then being one Heat treatment above the melting temperature of silicon is subjected, so that a SiC matrix is formed from the carbon of the organic material and the silicon particles in which the fibers are embedded. With this procedure, the infiltration of substances into a fiber blank can be dispensed with. Instead, the provision of the carbon via an organic material and the silicon via the silicon particles in appropriate layers, which are arranged in addition to layers with the fibers to be embedded, enables the formation of silicon carbide, which is homogeneous without the formation of pores on the fibers can be.

The silicon particles can be embedded in the layers with the organic material and the silicon particles in the organic material and / or can be arranged on the organic material.

The organic material can be a thermoplastic polymer.

The organic material can be pyrolyzed or burned during the heat treatment so that only the carbon of the organic material or thermoplastic polymer is provided for silicon carbide formation, while other components of the organic material or thermoplastic polymer burn and / or outgas.

The organic material can in particular be selected from the group comprising waxes, in particular synthetic waxes, polyamides, polyethylene and polyolefins.

The layers with an organic material and silicon particles as well as the layers with fibers can be arranged alternately with one another or alternately so that the fibers are evenly enclosed by the matrix that is created by the formation of the silicon carbide.

The green body, which is formed from the layers with an organic material and silicon particles and the layers with fibers, can be produced in a shape corresponding to the shape of the component to be produced, so that the green body already has a near net shape.

The layers with an organic material and silicon particles and the layers with fibers made of ceramic and / or carbon can be glued to one another with the aid of an adhesive to form the green body. Additionally or alternatively, the components of the individual layers, for example the silicon particles with the organic material or with one another, and the fibers made of carbon and / or ceramic, can be glued to one another. An adhesive from the group consisting of waxes, in particular synthetic waxes, polyamides, polyethylene and polyolefins, can be used to bond the layers with an organic material and silicon particles and the layers with fibers made of carbon and / or ceramic and / or their components includes.

The green body can be compressed during the heat treatment, in particular a HIP process (hot isostatic pressing HIP) can be carried out.

Silicon carbide fibers or coated silicon carbide fibers can be used as ceramic fibers, it being possible for the silicon carbide fibers to be coated with a substance selected from the group consisting of BN, Si ₃ N ₄ , SiC and C.

Figure list

• 1 eine Querschnittsdarstellung eines Grünkörpers eines ersten Ausführungsbeispiels,
• 2 eine Querschnittsdarstellung des aus dem Grünkörper der 1 gefertigten Bauteils,
• 3 eine Querschnittsdarstellung eines Grünkörpers eines zweiten Ausführungsbeispiels,
• 4 eine Querschnittsdarstellung des aus dem Grünkörper der 2 gefertigten Bauteils und in
• 5 einen Querschnitt durch eine beschichtete Faser.

The accompanying drawings show in a purely schematic manner

• 1 a cross-sectional representation of a green body of a first embodiment,
• 2 a cross-sectional view of the from the green body of 1 manufactured component,
• 3 a cross-sectional representation of a green body of a second embodiment,
• 4th a cross-sectional view of the from the green body of 2 manufactured component and in
• 5 a cross section through a coated fiber.

EXAMPLES

Further advantages, characteristics and features of the present invention will become apparent in the following detailed description of the exemplary embodiments. However, the invention is not restricted to these exemplary embodiments.

The 1 shows a purely schematic cross-sectional view of a green body produced according to the invention for producing a component from a fiber-reinforced material. The in 1 The green body shown comprises a total of five layers 1 to 5 that are arranged one above the other. In the exemplary embodiment shown, the green body has a cuboid shape, but it is also possible to form a green body which can have any desired outer contour and a wide variety of layer structures.

The first, third and fifth layers 1 , 3 , 5 of the in 1 The green body shown is each made of a thermoplastic material 6th formed in the silicon particles 7th are stored.

The second and fourth layers 2 , 4th is made up of a layer of SiC fibers 8th formed, wherein the longitudinal axis of the respective fibers are arranged parallel to one another. However, it is also conceivable that the fibers are aligned differently to one another both in one layer and in different layers. The fibers 8th are by means of an adhesive 9 , for example by an organic resin, together to form the respective layer 2 , 4th glued.

All layers 1 to 5 of the green body can also be glued to one another by an adhesive and by pressing together to form the green body, as shown in FIG 1 is shown.

The green body out 1 is subjected to a heat treatment which is carried out at a temperature above the melting point of silicon and in which an external pressure can be exerted on the green body, wherein the pressure can preferably act on all sides of the green body. For example, the heat treatment can be carried out by hot isostatic pressing at a temperature above the melting temperature of the silicon particles 7th be performed. The heat treatment melts the silicon particles 7th and the silicon reacts with the thermoplastic material 6th so that a SiC matrix 11 is formed in which the SiC fibers 8th which were arranged in the green body are incorporated. The components of the thermoplastic material 6th and the glue 9 with the exception of the carbon are in the reaction of the thermoplastic material 6th With the silicon, the silicon particles are converted into silicon carbide in the gaseous state, so that they can leave the green body through appropriate outgassing and a component 10 with a SiC matrix 11 with embedded SiC fibers 8th arises.

The 3 and 4th show a second exemplary embodiment for the production of a component according to the invention 30th made of a fiber-reinforced material with a SiC matrix 31 . In the second exemplary embodiment, no thermoplastic material with embedded silicon particles is used, but rather in the first, third, fifth and seventh layers 21st , 23 , 25th and 27 of the in 3 The green body shown is in each case a thermoplastic material 28 arranged as a carrier for silicon particles 29 serves on the thermoplastic material 28 are arranged for example with the aid of an additional adhesive. However, it is also possible to use the silicon particles 29 directly on the thermoplastic carrier 28 by connecting the silicon particles 29 with the thermoplastic material 28 to arrange.

In addition to the first, third, fifth and seventh layers 21st , 23 , 25th and 27 are in the green body of the in 3 embodiment shown a second layer 22nd , a fourth layer 24 and a sixth layer 26th each of a lattice structure, a fabric or a mesh 32 made of SiC fibers 33 and 34 arranged with the SiC fibers 33 and 34 with their longitudinal axes essentially perpendicular to one another in the fiber braid 32 are arranged.

The green body according to the second exemplary embodiment, which is shown in FIG 3 is subjected to a heat treatment which is carried out at a temperature such that it adheres to the thermoplastic carrier 28 Adhering silicon particles melt and with the carbon of the thermoplastic material 28 react to form silicon carbide. Here, too, a corresponding external pressure can be exerted, for example during hot isostatic pressing, in order to bring about a compression of the material and a largely pore-free component 30th to generate as it is in 4th is shown. With the component 30th a SiC matrix is again provided in which the fiber braids 32 with the SiC fibers arranged perpendicular to one another 33 and 34 are embedded.

Instead of the SiC fibers shown in the previous exemplary embodiments, other fibers, such as carbon fibers, can also be used. One possibility is also coated fibers 35 to use, one of which in a cross-section in 5 is shown. The coated fiber 35 has a fiber core 36 , for example also made of silicon carbide, with a coating around the fiber core 37 made of a different material such as BN.

Instead of in the embodiments 1 and 2 of 1 to 4th The arrangement of fibers shown, other fiber arrangements can also be selected and a different arrangement of the individual layers is also possible, for example an arrangement deviating from the alternating arrangement of layers made of an organic, in particular thermoplastic material with silicon particles on the one hand and fibers on the other. It only has to be ensured that a reaction of the silicon particles with the carbon of the organic or thermoplastic carrier material to form the SiC matrix can take place during the heat treatment of the green body.

Although the present invention has been described in detail on the basis of the exemplary embodiments, it is obvious to the person skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features can be omitted or other types of combinations of features can be implemented without departing from the scope of protection of the appended claims. In particular, the present disclosure includes all combinations of the individual features shown in the various exemplary embodiments, so that individual features that are only described in connection with one exemplary embodiment can also be used in other exemplary embodiments or combinations of individual features that are not explicitly shown.

List of reference symbols

1

first layer

2

second layer

3

third layer

4th

fourth layer

5

fifth layer

6

Thermoplastic

7th

Silicon particles

8th

SiC fiber

9

adhesive

10

Component

11

SiC matrix

21st

first layer

22nd

second layer

23

third layer

24

fourth layer

25th

fifth layer

26th

sixth shift

27

seventh shift

28

Thermoplastic

29

Silicon particles

30th

Component

31

SiC matrix

32

Fiber braid

33

first fibers

34

second fibers

35

coated fiber

36

Fiber core

37

Fiber coating

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 8980027 B2 [0004]
• US 9440888 B2 [0005]
• US 5589115 A [0006]
• US 5476685 A [0007]
• US 9512044 B2 [0008]
• US 2016/0159066 A1 [0009]
• US 6773528 B2 [0010]

Claims (11)

Method for the production of components from ceramic fiber composite materials, in which fibers (8; 33,34) made of ceramic and / or carbon are embedded in a matrix (1 1; 31) made of silicon carbide, characterized in that layers (1,3,5 ; 21,23,25,27) with an organic material (6; 28) and silicon particles (7; 29) and layers (2,4; 22,24,26) with fibers (8; 33,34) and are shaped into a green body, the green body then being subjected to a heat treatment above the melting temperature of silicon, in which a SiC matrix (11; 31) is formed in which the fibers (8; 33, 34) are embedded. Procedure according to Claim 1 , characterized in that the silicon particles (7; 29) are embedded in the organic material and / or are arranged on the organic material. Method according to one of the preceding claims, characterized in that the organic material (6; 28) is a thermoplastic polymer. Method according to one of the preceding claims, characterized in that the organic material (6; 28) is selected from the group comprising waxes, polyamides, polyethylene and polyolefins. Method according to one of the preceding claims, characterized in that layers (1,3,5; 21,23,25,27) with an organic material (6; 28) and silicon particles (7; 29) and layers (2, 4; 22,24,26) with fibers (8; 33,34) are arranged alternately. Method according to one of the preceding claims, characterized in that the green body is produced in a shape corresponding to the shape of the component (10, 30) to be produced. Method according to one of the preceding claims, characterized in that the layers made of an organic material and Si particles and the fibers made of carbon and / or ceramic and / or their components are glued together. Method according to one of the preceding claims, characterized in that an adhesive (9) from the group is used to glue the layers made of an organic material and Si particles and the fibers made of carbon and / or ceramic and / or their constituents Waxes, in particular synthetic waxes, polyamides, polyethylene and polyolefins. Method according to one of the preceding claims, characterized in that the green body is compressed during the heat treatment. Method according to one of the preceding claims, characterized in that silicon carbide fibers and / or coated silicon carbide fibers (35) are used as ceramic fibers. Procedure according to Claim 10 , characterized in that the silicon carbide fibers (35) are coated with a substance selected from the group comprising BN, Si ₃ N ₄ , SiC and C.

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