WO2020002357A1 - Ceramic fibre-composite cmc moulding, intermediate product in production, and production method therefor - Google Patents

Abstract

The invention relates to a CMC moulding, such as for example a turbine component, of ceramic-matrix composite material "CMC", in particular also a ring segment of a gas turbine and/or a component of an exhaust system, which is at least partially constructed from CMC, that is to say a ceramic-matrix composite, and/or from a CMC-metal hybrid, and realizes a novel constructing concept, which is improved in particular with regard to the mechanical, thermomechanical and/or thermal stability. The concept, presented here for the first time, of the "WRAPSTACK" composite represents a very robust CMC moulding which advantageously combines the excellent mechanical stability and damage tolerance of a CMC sub-element produced by the WRAP construction concept with the advantageous properties of a CMC sub-element formed by the STACK construction concept, with a surface that is especially stable in the hot gas flow.

Description

description

Ceramic fiber composite CMC molded body, intermediate in the manufacture, and manufacturing process therefor

The invention relates to a CMC molded body such as, for example, a turbine component made of ceramic matrix composite material “CMC”, in particular also a ring segment of a gas turbine and / or a component of an exhaust gas line, which is at least partially made of CMC, that is to say — ceramic matrix composite - And / or from a CMC metal hybrid, is built and a new, in particular with regard to the mechanical, thermomechanical and / or thermal stability, realized on construction concept.

So far, such CMC moldings such as ring segments, for example for stationary gas turbines, made of nickel-based superalloys with additional protective coatings, e.g. TBC coatings used. Although the properties of these materials are constantly being developed, this technology seems to be quite exhausted and, according to the general assessment of the experts, only a small substantial increase is still possible.

In contrast, the technology of component construction with CMCs, i.e. the fiber-reinforced ceramic materials, is an alternative that can be used alone and / or in combination with metal or metal alloy parts, as a so-called CMC-metal hybrid molded body Novel moldings such as turbine components and / or components in an exhaust line can still be used profitably, i.e. leading to substantial increases. Super alloys, such as nickel super alloys, are preferably used as metals.

As a rule, a CMC molded body comprises layers which in turn have fibers, in particular in the form of a fiber composite, a fabric and / or a three-dimensional composite made of fibers especially made of ceramic reinforcing fibers, which are embedded in a likewise preferably ceramic matrix. To produce the CMC shaped body, CMC prepreg layers are preferably laminated to one another and subsequently sintered to form the ceramic CMC shaped body. The arrangement of the CMC prepreg layers in relation to one another is a critical point. For this reason, constant research is being carried out on an optimal arrangement of the CMC layers with respect to one another, that is to say on construction concepts for the arrangement of the layers into three-dimensional shaped bodies, be it for turbines and / or for elements of an exhaust tract.

Turbine components that are already known include, for example, laminate made of CMC layers. The laminates are deposited and / or stacked, formed from CMC prepreg layers on the one hand in the so-called stack construction concept on a metal core and / or on a support structure and on the other hand in the so-called winding construction concept around a core and / or a support structure is wrapped around and / or inserted and / or deposited in a mold or "mold". In both cases, after the CMC prepreg layers have been dried and / or tempered, they are sintered with or without a support structure.

In particular, in the manufacture of CMC-based ring segments for stationary gas turbines, either the wrap, that is, the winding structure concept, or the stack, that is, the stack structure concept, has so far been implemented.

CMC moldings produced in this way for turbine components and / or components of an exhaust line are then fundamentally suitable for being exposed to extremely high thermal, thermo-mechanical and mechanical loads during operation. However, they should also be suitable for effective component cooling and / or have a surface which has sufficient hardness for pretreatment by roughening for a suitable adhesion of a TBC layer to be applied. These two last points, the formation of the cooling structure within the component on the one hand and the surface quality on the other hand still cause problems according to the conventional assembly concepts. In addition, conventionally constructed CMC molded parts show anisotropic strength.

With the "wrap" - or, to put it internationally, "WRAP" construction concept, the CMC layers are built up in layers parallel to the outer contour of the finished molded body. In this way, complex components such as ring segments can also be produced with the aid of appropriate molding tools. However, a major disadvantage of the WRAP concept is the weak matrix layers with low interlaminar strength that are oriented parallel to the component surface. This can lead to large-scale delamination if the outer layers are damaged - for example by impact, "rub-in" and / or high thermal stress. In particular, it is difficult to CMC parts based on the WRAP assembly concept with a permanently stable To provide protective layer, such as a thermally sprayed run-in layer, a thermal barrier coating “TBS” layer and / or an environmental barrier coating “EBC” layer, because these do not mechanically roughen before the coating is applied withstand.

In the case of the "stack" - or international "STACK" construction concept, the individual layers are generally perpendicular to the outer contour of the finished molded body, although the mechanical final contour machining works well in contrast to the WRAP concept, but none in the vertical direction Tractive forces can be transmitted and there is a risk of cracks. In particular, the low interlaminar strength of a CMC sub-element can have a disadvantageous effect on the thermo-mechanical resilience and / or the surface hardness of the finished molded body.

Therefore, there is still a need to include a new assembly concept for a CMC molded body or a CMC hybrid molded body to create increased mechanical, thermomechanical and / or thermal resilience.

The object of the present invention is therefore to provide a structural concept for CMC molded articles which, compared with the prior art, shows improved mechanical, thermomechanical and / or thermal resistance.

This object is achieved according to the invention by the object as disclosed in the description, the figures and the claims.

Accordingly, the subject of the invention is a ceramic fiber composite CMC molded body, representing a composite of at least two CMC sub-elements, with a first sub-element laminated ceramic matrix composite layers in the winding-up concept and a second sub-element laminated ceramic matrix composite layers in the stack. Construction concept includes such that the second sub-element is at least partially arranged within the first sub-element.

In addition, the invention relates to an intermediate product, an unsintered ceramic fiber composite CMC molded body, which has a composite of at least two CMC sub-elements, with a first sub-element laminated ceramic matrix composite prepreg layers in the winding construction concept and a second Partial element comprises laminated ceramic matrix prepreg layers in the stack construction concept, such that the second partial element is at least partially arranged within the first partial element.

The present invention also relates to a method for producing a CMC molded body, wherein in a first process step to form the intermediate product, two CMC sub-elements, a first CMC sub-element in the wrap-up construction concept and a second CMC sub-element in Stack construction concept, are produced, which then in a subsequent process step with each other to form a Composite can be combined, with a second CMC part, which is at least partially internal and realized in the stack construction concept, is at least partially surrounded by a first CMC part realized in the winding construction concept, so that in a subsequent sintering process step the intermediate product with the composite of the at least two CMC sub-elements is sintered.

In the present case, “laminating” means when at least two flat sections, for example two prepreg-CMC laminate layers or a prepreg-CMC laminate layer and a substrate, are connected to one another by pressure and / or temperature The surfaces of the surfaces to be joined overlap completely or only partially. When laminating the CMC molded bodies, for example with the WRAP, very differently cut CMC laminate layers can be connected, the surfaces of which cannot be made identical because the surfaces are identical differentiate in shape and scope: With the STACK, stacks can also be stacked from several prepreg-CMC laminate layers with exactly the same cut and thus laminated together.

According to a preferred embodiment of the invention, the CMC molded body comprises at least one partial element made of metal and / or a metal alloy. This is then a so-called “CMC hybrid molded body”.

According to a preferred embodiment of the invention, the outline of the CMC molded body has at least one curved edge. For example, a side wall of the CMC molded body can have a meandering course, or the side wall is curved in a convex or concave manner. Of course, two opposite side walls can also show a parallel curved course, as is useful, for example, for producing a ring segment. For example, a ring segment of a gas turbine is a “curved” shaped body in the present sense.

A “CMC” shaped body is a body that is made entirely or partially of ceramic matrix composite material, also known internationally as Ceramic Matrix Composite, or CMC for short. This material regularly comprises reinforcing fibers in a ceramic matrix. The material is preferably used in Formed CMC prepreg layers, which comprise fibers in dried slip, processed and then sintered.

CMC can, for example, be based on silicon carbide or based on metal oxide. Prominent representatives of this class of materials are the “Ox-Ox-CMC and the SiC-CMC. In the case of an Ox-Ox-CMC, there are, for example, aluminum oxide fibers or corresponding fiber composites which are impregnated with an aluminum oxide and / or an aluminum oxide-mullite slip to form the CMC layer. This is similar for the SiC-based CMC variant, there are corresponding silicon carbide fibers which are then embedded in a silicon carbide slip which is burned out to form the matrix.

A “CMC molded body” comprises the finished sintered CMC layer-matrix composite. The “intermediate product” comprises the fully laminated but not yet sintered prepreg-CMC laminate layers.

A layer made of the fiber composite or fiber fabric covered with slip is then referred to as the “CMC layer”.

"Laminating" is the process by which the individual CMC layers are stacked on top of one another and / or connected in some other way. When laminating, for example, the CMC layers are neither tempered nor sintered, but may already have dried, not yet tempered and so on The sintered CMC layers are preferably also subjected to a temperature treatment in order to form a prepreg CMC layer. As an intermediate product, a molded article is obtained from prepreg CMC layers before sintering.

According to an advantageous embodiment of the invention, at least a first and a second CMC sub-element are connected to form the CMC molded body in such a way that a material-locking bond results. The first and the second CMC sub-elements are connected to one another, for example, by a high-temperature ceramic phase, the matrix and / or a glass ceramic.

According to a further advantageous embodiment of the invention, at least a first and a second CMC sub-element are connected to form the CMC molded body in such a way that a positive connection results.

In particular, according to one embodiment, the construction of a curved outer CMC sub-element, which is produced using a WRAP construction concept, is carried out by laminating individual CMC layers on a support structure. The second STACK-CMC sub-element is introduced into this curved CMC sub-element. To this end, the first CMC sub-element is open on at least one side.

A composite produced in this way can, for example, be wrapped again with a WRAP system.

The finished CMC molded body can then optionally be combined with one or more further STACK and / or WRAP-CMC parts.

This combined construction concept of the "WRAP-STACK" creates a 3-dimensional CMC structure by laminating CMC prepreg layers.

Ring segments of the first and second turbine series are particularly attractive candidates for the use of CMC Shaped bodies according to the present invention, which promise significant cooling air savings and increases in efficiency. Ring segments are subject to very high thermal and mechanical loads, which require a very robust construction concept and a suitable cooling scheme - for example including a thermal protective layer.

According to an advantageous embodiment of the invention, the shaped body in the turbine and / or in the exhaust line is arranged in such a way that the interior, realized in the stack construction concept, CMC sub-element forms the surface oriented towards the hot gas and the outer surface, in the winding Construction concept implemented CMC sub-element that provides the surface required for structural stability, for example of the ring segment.

The invention is explained in more detail below with reference to a figure:

Figures la and lb show the schematic structure of a ring segment according to an embodiment of the inven tion.

FIG. 1 a shows the first CMC sub-element formed according to the WRAP construction concept - not yet filled - and in perspective view and FIG. 1 b shows a cross section of the composite of the first and second CMC sub-elements.

FIG. 1 a shows a perspective view of a tub formed from a first CMC sub-element 1 in the WRAP assembly concept. This forms, for example, filled or partially filled, a ring segment of a gas turbine.

The first CMC sub-element 1 has two longer sides 2 and two shorter sides 6. The longer sides 2 are bent in a ring. The sub-element 1 defines with five sides a cavity 3 which, as shown for example in FIG. 1b, with a second, formed in the STACK construction concept, CMC sub-element 4 can be filled and / or into which a second CMC sub-element fits.

The production of the first CMC sub-element 1 according to the WRAP assembly concept can be achieved by laminating into a corresponding shape and subsequent compression and heat treatment. The CMC part 4 arranged in the stack assembly concept on the hot gas side, on the other hand, is made by stacking prefabricated and accordingly processed CMC laminate layers in the prefabricated first CMC sub-element 1.

The contact areas between the individual CMC laminate layers of the second CMC sub-element 4 and / or between the STACK-CMC sub-element 4 and the WRAP-CMC sub-element 5 can be with the matrix used for the CMC laminate layer, the slip, a high temperature stable ceramic slurry and / or via a glass ceramic and corresponding penetration.

The longer side walls 2 of the first CMC sub-element 1 have holes 7 which can be used, for example, for fastening the ring segment and / or for cooling ducts.

FIG. 1b shows a cross section of the first CMC sub-element 1 known from FIG. 1 a. The sides 5 in the WRAP construction concept and the second, internal CMC sub-element 4 are formed as a STACK. As can be seen, this second CMC sub-element 4 gives the finished CMC molded body from the two CMC sub-elements 4 and 5 stability, so that the sides 2 and 6 of the tub 1, as well as the bottom of the tub 1, in shape being held.

The CMC assembly concept presented for a - in particular curved - molded body, such as a ring segment, offers a multitude of advantages, which are briefly summarized below.

- The combination of WRAP-CMC part on the housing and STACK-CMC part on the hot gas side - for example a gas turbine - is superior to the previously known ring segments in terms of temperature stability, torsional rigidity, damage tolerance and / or strength.

- The production of the ring segment can at least

 partially automate, especially when placing the CMC laminate layers on a support structure and / or in a mold.

 - The specific roughness and characteristics of the processed CMC surface, in particular the STACK-CMC partial surface, ensures very good adhesion of thermally sprayed protective layers, such as an inlet layer of a TBC and / or an EBC.

The concept of the "WRAPSTACK" composite presented here for the first time represents a very robust CMC molded body, which advantageously has the excellent mechanical stability and damage tolerance of a CMC sub-element manufactured in the WRAP assembly concept with the advantageous properties of a STACK assembly concept formed CMC sub-element with its specially stable surface in the hot gas stream connec det.

Claims

claims 1. Ceramic fiber composite CMC molded body, representing a composite of at least two CMC sub-elements, a first sub-element comprising laminated ceramic matrix composite layers in the winding construction concept and a second sub-element laminated ceramic matrix composite layers in the stack construction concept, such that that the second sub-element is at least partially arranged within the first sub-element. 2. Molded body according to claim 1, which is present as a CMC hybrid molded body, that is to say additionally comprises at least a third partial element made of metal and / or a metal alloy. 3. Shaped body according to one of claims 1 or 2, the floor plan has at least one curved edge. 4. Shaped body according to one of the preceding claims, in which two opposite side walls are bent and pa rallel. 5. Shaped body according to one of claims 1 or 2, which is formed on an oxidic material basis. 6. Shaped body according to one of claims 1 or 2, which is formed on a silicon carbide material basis. 7. Shaped body according to one of the preceding claims, wherein the first CMC sub-element is trough-shaped. 8. Shaped body according to one of the preceding claims, wherein the second CMC sub-element is positively connected to the first CMC sub-element. 9. Shaped body according to one of the preceding claims, in which the second CMC sub-element is materially connected to the first CMC sub-element. 10. Intermediate product, an unsintered ceramic Representing fiber composite CMC molded body, which has a composite of at least two CMC sub-elements, a first sub-element laminated ceramic matrix composite prepreg layers in the winding construction concept and a second sub-element laminated ceramic matrix composite prepreg layers in the stack construction concept comprises, such that the second sub-element is at least partially arranged within the first sub-element. 11. The method for producing a shaped body according to claim 10, wherein in one  - First method step, to form the intermediate product, comprising at least two CMC sub-elements, a first CMC sub-element in the winding construction concept and a second CMC sub-element in the stack construction concept, each comprising prepreg-CMC laminate layers, laminated,  Then, in a subsequent process step, these two CMC sub-elements are combined with one another to form the composite, with the composite comprising a second CMC part, at least partially in the internal structure and in the stack construction concept, of a first one in the winding construction concept CMC part is at least partially surrounded. 12. The method according to claim 11, wherein  in a subsequent sintering process step, the intermediate product according to claim 10 with the composite of the at least two CMC sub-elements is sintered to form the CMC molded body. 13. The method according to any one of claims 11 or 12, in which - In a subsequent process step, a ring segment for a turbine is produced from the CMC molded body by mechanical processing. 14. The method according to any one of claims 11 to 13, wherein in a subsequent process step, the CMC molded body is at least partially coated with a thermal protective layer. 15. Ring segment of a device operated with hot gas, comprising a ceramic fiber composite CMC molded body, comprising a composite of at least two CMC sub-elements, a first sub-element being laminated ceramic Matrix composite layers in the winding construction concept and a second sub-element comprises laminated ceramic matrix composite layers in the stack construction concept, such that the second sub-element is arranged at least in part within the first sub-element.