EP3478645A1

EP3478645A1 - Process for manufacturing a ceramic matrix composite part

Info

Publication number: EP3478645A1
Application number: EP17742814.1A
Authority: EP
Inventors: Aurélia CLERAMBOURG; Marie LEFEBVRE; Sébastien Denneulin; Eric Philippe; Eric Bouillon
Original assignee: Safran Ceramics SA
Current assignee: Safran Ceramics SA
Priority date: 2016-06-29
Filing date: 2017-06-28
Publication date: 2019-05-08
Also published as: WO2018002525A1; FR3053328B1; US20200181029A1; FR3053328A1; CN109415269A

Abstract

The invention relates to a process for manufacturing a composite part comprising a fibrous reinforcement and a ceramic matrix present in the porosity of the fibrous reinforcement, the process comprising at least the following steps: a) the formation of the fibrous reinforcement by three-dimensional weaving of ceramic yarns (step E1), the fibrous reinforcement thus formed having an interlock weave; b) the formation of a first ceramic matrix phase in the porosity of the fibrous reinforcement (step E4); c) the introduction into the porosity of the fibrous reinforcement, after carrying out step b), of a powder comprising a mixture of SiC particles and carbon particles (step E5); and d) the infiltration of the fibrous reinforcement obtained after carrying out step c) by an infiltration composition in the melt state comprising at least silicon so as to form a second ceramic matrix phase in the porosity of the fibrous reinforcement and thus obtain the composite part (step E6).

Description

Process for manufacturing a piece made of ceramic matrix composite material

Background of the invention

The present invention relates to the general field of manufacturing processes of ceramic matrix composite material parts.

Various methods for manufacturing ceramic matrix composite material (CMC) parts are known. The method of chemical vapor infiltration (CVI process for "Chemical Vapor Infiltration") of a fibrous reinforcement is known. The CVI makes it possible to obtain parts having good mechanical properties as well as high densities. This method however has the disadvantage of being expensive.

The so-called "Pre-preg" process is also known in which pre-impregnated carbon precursor resin threads are formed into webs which are then draped to obtain a fibrous preform. The fiber preform is molded, baked, and finally infiltrated by a silicon alloy in the liquid state (infiltration technique in the molten state: "MI" for "Melt-Infiltration"). The production of a piece of complex three-dimensional shape by implementing this method can, however, be relatively difficult.

It should also be noted that the parts obtained by the MI technique may have a significant residual porosity, due in particular to the inhomogeneous penetration of the molten metal into the fibrous reinforcement. The mechanical properties of the parts obtained by this method can therefore be improved.

There is therefore a need to have a relatively low cost implementation manufacturing method that allows to obtain a CMC piece of complex shape having improved mechanical properties and a low residual porosity rate.

Object and summary of the invention

The main object of the present invention is therefore to overcome such drawbacks by proposing a method for manufacturing a part made of composite material comprising a fibrous reinforcement and a ceramic matrix present in the porosity of the fibrous reinforcement, the process comprising at least the following steps:

a) the formation of the fibrous reinforcement by three-dimensional weaving of ceramic threads, the fibrous reinforcement thus formed having an interlock weave,

b) forming a first ceramic matrix phase in the porosity of the fibrous reinforcement,

c) introducing into the porosity of the fibrous reinforcement after implementation of step b) of a powder comprising ceramic particles and / or carbon particles, and

d) the infiltration of the fibrous reinforcement, after implementation of step c), with a melt infiltration composition comprising at least silicon so as to form a second ceramic matrix phase in the porosity of the fibrous reinforcement and thus obtain the piece of composite material.

The implementation of a fibrous reinforcement weave interlock weave provides better penetration of the powder particles in the porosity of the latter during step c). Indeed, the inventors have found that the interlock armor defines, after step b), porosity channels adapted to a better penetration of the particles in the thickness of the reinforcement. It follows that the melt infiltration composition will also penetrate more easily into the fibrous reinforcement, during step d), by wetting the ceramic and / or carbon particles already present in the porosity of the fibrous reinforcement. . In an exemplary embodiment, the porosity in the part obtained after implementation of step d) may be less than or equal to 5%, or even less than or equal to 3%. Thus, the mechanical properties of the piece of CMC material obtained are improved and the residual porosity is reduced. In addition, the use of three-dimensional weaving to achieve the fiber reinforcement makes it possible to obtain pieces of complex geometry.

In an exemplary embodiment, particles of SiC, Si ₃ N ₄ , BN, SiB ₆ , B ₄ C, or a mixture of such particles may be introduced during step c).

In an exemplary embodiment, SiC particles may be introduced during step c). A mixture of SiC particles and carbon particles is introduced in step c).

In an exemplary embodiment, the average particle size introduced during step c) may be less than or equal to 5 μm or even less than or equal to 1 μm. By "average particle size" is meant the size D ₅₀ of the particles. particles.

In an exemplary embodiment, the first ceramic matrix phase may comprise silicon carbide (SiC).

In an exemplary embodiment, the residual porosity volume rate in the fibrous reinforcement (= pore volume / volume of the fibrous reinforcement), after implementation of step b), may be between 30% and 35%.

In an exemplary embodiment, an interphase may be formed on the ceramic son before step b).

In an exemplary embodiment, the fiber reinforcement may comprise silicon carbide wires having an oxygen content of less than or equal to 1% atomic percentage.

Finally, the invention relates to the method described above wherein the manufactured part is a turbomachine part. The part can be a part of hot part of a gas turbine of an aeronautical engine or an industrial turbine. In particular, the part may constitute at least a part of a distributor, a wall of a combustion chamber, a turbine ring sector or a turbomachine blade. Brief description of the drawings

Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings provided without limitation. In the figures:

FIG. 1 is a flowchart representing the different steps of an exemplary method according to the invention,

FIG. 2 is a schematic view showing an example of interlock weave weave,

FIG. 3 is a photograph showing a section of a part obtained by a method according to the invention, and

- Figure 4 is a photograph showing a section of a piece obtained by a method outside the invention. Detailed description of the invention

An example of a method of manufacturing a piece of CMC material according to the invention will now be described in connection with the flowchart of Figure 1.

A first step E1 of the method (step a)) may consist of forming the fibrous reinforcement of the piece by three-dimensional weaving to obtain a fibrous reinforcement having an interlock weave. The fiber reinforcement may be formed of ceramic son, for example silicon carbide son. The fibrous reinforcement obtained during step E1 constitutes a fibrous preform of the part to be manufactured.

Examples of usable silicon carbide threads may be "Nicalon", "Hi-Nicalon" or "Hi-Nicalon-S" yarns marketed by the Japanese company NGS. The ceramic son of the fiber reinforcement may have an oxygen content less than or equal to 1% atomic percentage. "Hi-Nicalon-S" wires have such a characteristic.

By "three-dimensional weaving" or "3D weaving", it is necessary to understand a weaving mode whereby at least some of the warp threads bind weft threads on several weft layers. According to the invention, the fibrous reinforcement has an interlock weave. "Armor or interlock fabric" means a 3D weave armor in which each layer of warp thread C binds several layers of weft threads T with all the threads of the same warp column having the same movement in the thread plane. armor. In the example illustrated in FIG. 2, a weft layer is formed of two adjacent half-weft layers t-offset with respect to each other in the warp direction. We therefore have here 18 half-layers of weft positioned in staggered rows. Each warp C binds 3 half-layers of weft t. However, it is possible to adopt a non-staggered layout in which the weft threads of two adjacent weft layers are aligned on the same columns. A reversal of roles between warp and weft is possible in the present text and should be considered as also covered by the claims.

A step E2 of surface treatment of the ceramic son, prior to the formation of an interphase, is preferably carried out in particular to eliminate the size that may be present on the fibers. In a step E3, a defibrillation interphase can be formed by CVI on the ceramic son of the fibrous reinforcement. The thickness of the interphase may for example be between 10 nm and 1000 nm, and for example between 10 nm and 100 nm. After formation of the interphase, the fibrous reinforcement remains porous, the initial accessible porosity being filled only for a minority part by the interphase.

The interphase can be monolayer or multilayer. The interphase may comprise at least one layer of pyrolytic carbon (PyC), boron nitride (BN), silicon doped boron nitride (BN (Si), with silicon in a mass proportion of between 5% and 40%). %, the balance being boron nitride) or boron doped carbon (BC, with boron in an atomic proportion of between 5% and 20%, the balance being carbon). The interphase here has a function of defragilating the composite material which favors the deflection of possible cracks reaching the interphase after having propagated in the matrix, preventing or delaying the breaking of fibers by such cracks. Alternatively, it will be noted that it is possible to form the interphase on the ceramic son before weaving the fibrous reinforcement, that is to say before implementation of step E1 (step a)).

A step E4 of forming a first ceramic matrix phase in the porosity of the fibrous reinforcement (step b) is then carried out on the interphase which may have been previously formed or directly on the fibers of the fibrous reinforcement. This matrix phase can be formed by CVI. The first ceramic matrix phase may for example comprise SiC. The residual porosity rate of the fibrous reinforcement following this step E4 and before introduction of the powder may be greater than or equal to 30%, for example between 30% and 35%. In general, the residual porosity rate of the fibrous reinforcement after implementation of step E4 (step b)) is sufficient to allow the introduction of a powder into the porosity of the fibrous reinforcement and the formation of a second matrix phase.

Then, in step E5, the introduction of a powder comprising particles of ceramic material and / or carbon particles into the residual porosity of the fibrous reinforcement (step c)). To do this, the fiber reinforcement can be impregnated with a composition, for example in the form of a slip, introduced into the porosity of the fibrous reinforcement by methods known per se, for example by injection. Said composition may comprise the powder in suspension in a liquid medium. The ceramic particles may be particles of SiC, Si ₃ N ₄ , BN, SiB ₆ , B ₄ C, or a mixture of such particles. The size (D ₅₀ ) of the particles of the powder may be less than or equal to 5 Mm, or even less than or equal to 1 Mm. Once the powder has been introduced into the fibrous reinforcement, for example by injection of a slip, the fibrous reinforcement can be dried.

Then, in step E6, the fibrous reinforcement in which the powder introduced in step E5 is introduced is infiltrated with a melt infiltration composition (step d)) comprising at least silicon so as to form a second ceramic matrix phase in the porosity of the fibrous reinforcement and to finalize the densification to obtain the part. This infiltration step corresponds to a step of infiltration in the molten state (MI process). The infiltration composition may consist of pure molten silicon or alternatively may be in the form of a molten silicon alloy and one or more other components. The infiltration composition may comprise predominantly silicon mass, that is to say have a silicon mass content greater than or equal to 50%. The infiltration composition may, for example, have a silicon mass content greater than or equal to 75%. The constituent (s) present (s) within the silicon alloy may be selected from B, Al, Mo, Ti, and mixtures thereof. When the particles of the powder introduced in step E5 are particles of C, B ₄ C, or a mixture of these particles, a chemical reaction may occur between the infiltration composition and the powder particles during infiltration resulting in the formation of silicon carbide.

After step E6, the piece of material CMC is obtained. Such a piece of CMC material may be a static or rotary turbine engine part. Examples of turbomachine parts have been mentioned above. Such a piece may further be coated with an environmental / thermal barrier coating.

FIG. 3 shows a photograph of a sectional cut of CMC material obtained by an exemplary method according to the invention. In this test, the fibrous reinforcement has an interlock weave and has been pre-densified by CVI (step E4) to obtain a first phase of SiC matrix. After this pre-densification, the fibrous reinforcement had a residual porosity in volume of between 30% and 35%. In step E5, an SiC powder (sold by Marion Technologies under the reference SiC MT59) having an average size (D ₅₀ ) of particles of 0.8 μm was introduced inside the porosity of the fibrous reinforcement. pre-densified. Finally, the infiltration (step E6) was carried out using pure silicon (marketed by HC Starck under the reference Silicium Grade AX-20). The photograph of FIG. 3 shows the matrix M and the wires F in the piece of CMC material thus obtained. With the method according to the invention, the overall porosity measured in the room is less than 1%.

For comparison, a test similar to that described above was carried out with the difference that the weave is multi-satin instead of interlock. Figure 4 is a photograph showing a sectional view of the CMC material part obtained in this test. Black pores are visible in the photograph of FIG. 4. An overall porosity greater than 15% has been measured in the part, and it can be seen in FIG. 4 that this porosity is also present between the F yarns. Thus, it can be seen that it is more difficult to fill the porosity in the fibrous reinforcement when the latter has a weave that is not interlocked. The mechanical properties are therefore less for this part than with that obtained in the previous test using a fibrous reinforcement with interlock weave.

Claims

A method of manufacturing a composite material part comprising a fibrous reinforcement and a ceramic matrix present in the porosity of the fibrous reinforcement, the method comprising at least the following steps:

a) the formation of the fibrous reinforcement by three-dimensional weaving of ceramic yarns (step E1), the fibrous reinforcement thus formed having an interlock weave,

b) forming a first ceramic matrix phase in the porosity of the fibrous reinforcement (step E4),

c) introducing into the porosity of the fibrous reinforcement after carrying out step b) of a powder comprising a mixture of SiC particles and carbon particles (step E5), and

d) the infiltration of the fibrous reinforcement, after implementation of step c), with a melt infiltration composition comprising at least silicon so as to form a second ceramic matrix phase in the porosity of the fibrous reinforcement and thus obtain the composite material part (step E6).

The method of claim 1, wherein the first ceramic matrix phase comprises silicon carbide.

3. The method of claim 1 or 2, wherein the average particle size, introduced in step c), is less than or equal to 5 Mm, for example 1 Mm.

4. Method according to any one of claims 1 to 3, wherein the residual porosity rate in the fibrous reinforcement, after implementation of step b), is between 30% and 35%.

The method of any one of claims 1 to 4, wherein an interphase is formed on the ceramic wires prior to step b) (step E3).

The method of any one of claims 1 to 5, wherein the fibrous reinforcement comprises silicon carbide wires having an oxygen content of less than or equal to 1 atomic percent.

7. Method according to any one of claims 1 to 6, wherein the manufactured part is a turbomachine part.