WO2018141574A1 - Cmc turbine component with complex cooling structures and method for the production thereof - Google Patents

Abstract

The invention relates to a non-metal turbine component, particularly a gas turbine component, for example for stationary gas turbines, consisting of ceramic matrix composite (CMC) materials. A CMC turbine component comprising fine and complex cooling channel structures is provided for the first time by the invention. These cooling channel structures are produced inside the CMC turbine component without said component being subjected to mechanically stressful methods such as etching, milling, cutting etc. This can be seen, for example, on the inner walls of the cooling channels.

Description

description

CMC turbine component with complex cooling structures and method for the production thereof

The invention relates to non-metallic turbine components, in particular gas turbine components, for example for stati ^¬ onary gas turbines, made of ceramic matrix composite materials (CMCs).

Turbine components, particularly turbine blades, made at least in part of CMCs have the advantage over metallic components that they can be used in stationary turbines, such as gas turbines, at significantly higher temperatures. This means that with the increase of the operating temperature an increase in efficiency of the gas turbine is possible and in particular that under certain circumstances efficiencies greater than 63% can be achieved. The CMC material is a ceramic composite consisting of ceramic fibers and / or fiber fabrics, such as mullite and / or alumina fiber, which is embedded in a ceramic matrix of - again, for example - alumina. From WO 2016/159933 such a turbine component is known.

However, thermal limits are also set for this material, which are achieved, inter alia, with the temperature at which the reinforcing fibers start to recrystallise. For a long service life of the gas turbine component under the above-mentioned operating conditions, cooling is therefore essential.

Although suitable cooling structures are known for metallic Gasturbi ^¬ nenkomponenten, but not for those from - possibly even very porous - CMCs. So far

Cooling structures and / or cooling channels in metallic gas turbine components, ie, for example, in blades and / or blades, produced by casting processes. In this case, casting cores are used according to the prior art for internal cooling structures, which image the filigree cooling channels and / or structures during the metal casting and, above all, are inaccessible in the interior of the turbine component. Cooling channels that are accessible from the outside are, in contrast, introduced by erosion and / or laser drilling. Accordingly, it is an object of the present invention to provide a turbine component which is at least partially made of CMC and has suitable cooling structures in the CMC, as well as to provide a method for the production of cooling structures in such turbine components.

This object is achieved by the subject matter of the present ^¬ invention as is disclosed in the description of the figures and the claims. Accordingly, the subject of the present invention ei ^¬ ne turbine component, which is at least partially made of ceramic matrix composite material by means of a lamination process, wherein placeholder in the CMC prepreg, a CMC prepreg precursor and / or the CMC prepreg layers formed laminate before and / or be introduced during the lamination process, which are removable during sintering of the turbine component by decomposition and / or evaporation and leave defined cavities in the CMC, which are used as cooling structures.

The cavities formed by the removal of the placeholder are identifiable depending on placeholder, because they have, unlike subsequently cut, etched or milled channel structures no sharp edges, but smooth surfaces. For example, there are no cut-off fibers on the walls of the cavities formed according to the invention, but the cavities are generally without cut damage to a ceramic reinforcing fiber in the CMC educated. In this case, of course, a cracked and / or separated reinforcing fiber in a cooling channel of the finished CMC component can not be excluded in individual cases. The usable here wildcards are flexible, pliable or rigid, depending on the type cooling channel is desired in the finished construction ^¬ part. For example, it is orga nic ^¬ based polymeric plastic sacrificial micro tubes, Plas ^¬ tik-victim channel structures and / or plastic sacrificial fibers, in particular carbon-based, organic fibers. The Materi ^¬ alien the sacrificial elements are directed thereafter, of the type of ceramic reinforcing fibers and ceramic matrix in which CMC. It is crucial that the sacrificial material with the ceramic material under pressure and temperature increase, such as the debinding step before the sintering ^¬ step, not react with the ceramic material and that the vaporous decomposition products of the sacrificial material also no reactions and / or damage to the Ceramics cause.

The sacrificial micro tubes are, for example KunststoffPro ^¬-products, for example, based on organic, inorganic and / or organometallic polymers which, in turn, for example, used nalstrukturen in the form of tubes and / or injection molded Ka.

The sacrificial fibers are fibers, fibrous webs and / or fiber composites in which at least two types of fibers are present, at least one first type of fiber which remains stable under the conditions of sintering the CMC component and at least ei ^¬ ne second type of fiber, among the Conditions of sintering of the CMC component decompose and evaporate. This fiber composites with at least two types of fibers are also called Hyb ^¬ ridfasern, hybrid fiber fabric and / or hybrid fiber composites.

This makes it possible for the first time to represent turbine components with complex cooling channel structures. Complex cooling channel structures are located in the turbine components in some areas or continuously before. Doing all kinds can be easily realized by cooling structures, because in areas where increased cooling advantageous is a greater density of cooling ^¬ channel structures are present than in the regions in which examples less cooling channels are required pitch.

Thus, closer to the core, a higher density of cooling structures may be provided in some regions than closer to the surface of the laminate.

Cooling-air structures in the turbine component which are of very thin-walled design are understood as "complex cooling-channel structures." Cooling-channel structures, for example, are described in US 2016/0376957 A1.

When lamination for the production of the turbine component from CMCs in a first step CMC prepreg are Herge ^¬ represents, that is fibers, fiber woven fabric and / or fiber composites, which are infiltrated with a ceramic matrix and / or impregnated and, deposited on molds, such as press cores , in particular stored in layers, that is laminated, are. As CMC prepreg laminate, a stack is referred to meh ^¬ of exemplary CMC prepreg layers of impregnated fabric in the present case, which is sintered for producing a CMC turbine component.

The fabrics used are to be retained in the finished part, and therefore, the fibers forming the fabric are ent ^¬ speaking of ceramic material that is stable to the Sinte- approximately process conditions. It is particularly advantageous if the fibers have at least portions which are kris ^¬ tallin and their crystallization is maintained during the sintering, which are therefore neither subject to re-crystallization nor a change in the modification by the sintering process.

In these CMC prepreg laminates the placeholder preference ^{¬ are} introduced. The placeholders are also inside the CMC prepreg laminates and / or CMC prepreg sheets and optionally have a connection opening on the surface. Furthermore, placeholders can pierce CMC prepreg layers or portions of layers. For example, the CMC prepreg laminates are also formed around the placeholders.

Thus, in at least one lower CMC prepreg ply placeholder ^¬ be introduced, which do not pass the upper CMC prepreg plies extend prior to the application of an upper CMC prepreg ply. The placeholders may pierce multiple CMC prepreg layers and / or be disposed along a CMC prepreg layer. After sintering cavities form at ^¬ put the wildcard at least occupy the space of the placeholder, but under certain circumstances, because the removal of the placeholder usually during

Debinding step takes place under gas evolution, ^{¬ Kings} nen cavities may be larger or smaller than the incorporated in the CMC prepreg layer placeholder. The CMC prepreg laminate is compressed in a second process step, preferably by autoclaving, at high pressure and dried.

A lamination method is known, for example, from WO

2016/159933 known.

After sintering, a finished CMC component is obtained, wherein fibers, fiber fabric and / or fiber composite, which are stable against ^¬ over the conditions of the sintering process, substantially unchanged, ie not or only slightly recrystallize, for example, during sintering.

The cavities form, for example thin-walled and / or com plex ^¬ channel structures. These are, for example, along fibers, fiber fabrics and / or fiber composites and / or perpendicular thereto, so that they pass through at least one plane or layer, but usually several planes or layers vertically. In order to form microchannel structures along the fibers, the fiber fabric and / or the fiber composites, micro-tubes containing the fibers are inserted into a CMC prepreg laminate which is burnt out during drying, debindering and / or during sintering of the CMC.

Alternatively or additionally, hybrid fibers, woven fabrics and / or composites may also be incorporated into a CMC prepreg laminate to form the micro-hoses and / or the injection-molded channel structures.

Hybrid fiber composites are for example ^3-¬ dimansionale fiber composites, in which two different Fasermate- are at least rials processed, for example, ceramic fibers and carbon fibers. The principle is that a first type of fiber, for example, a ceramic fiber is stable to the conditions of sintering, whereas a second type of fiber during sintering, especially in the

Debinding step is removable and leaves cavities, which are used in the finished component as a cooling channel. For example, the two types of fibers are woven together and / or braided together to form hybrid structures with sacrificial fiber cords, sacrificial fiber fabrics, and / or sacrificial fiber composites.

In braiding any 3-dimensional fiber composites can be used with placeholders to form the CMC prepreg layers.

These hybrid structures make it possible to realize very delicate cooling channel structures. For example, sacrificial fibers may be braided around the stable ceramic fibers, or vice versa, different diameters of sacrificial fibers and stable fibers may be combined, and tissues having sacrificial fibers of various diameters may serve to form desired zones in the turbine component with different thicknesses. to receive canceled cooling channel structures after sintering.

By using thin sacrificial fibers, for example carbon fibers with 500 denier to 3000 denier, correspondingly fine cooling channel structures can be produced. By using correspondingly thicker sacrificial fibers, for example in the range from 7000 to 15,000 denier, correspondingly larger cooling channel structures can be formed.

When using sacrificial micro-hoses, which are removed during the sintering process, formed in the finished CMC component, for example, cooling channels that a

Have diameters of lOOym to 3mm, in particular from 300ym to 2mm, more preferably in the range of 500ym to 1.5mm.

By incorporating sacrificial micro-tubes and / or sacrificial channel structures and / or sacrificial fibers into the CMC prepreg laminate, cooling channels with the stated diameters can be formed in different regions of the CMC component.

For example, areas with cooling channels and areas without cooling channels alternate, or areas with three different diameters on cooling channels with areas with only one diameter of cooling channels. In particular, filigree cooling channels and structures that are located inside the CMC component can be produced in this way. The cooling channel structures simulate the position of the placeholders before the sintering process. Accordingly, the cooling duct structures ^¬ braided and interwoven hybrid fibers can have very complex structures, for example, wind around the reinforcing fibers of the CMC component.

The invention is explained in more detail below with reference to selected examples: FIGS. 1 a and 1 b show a photograph of a CMC turbine component with a placeholder before the sintering process and with a cooling channel after the sintering process. Figures 2a to 2d show schematically the lamination process with installation of placeholders

Figures 3a and 3b show an exemplary hybrid fiber composite a) without laminate in a schematic, perspective DarStellung; b) within a CMC prepreg laminate;

FIGS. 4a and 4b show the installation of 2D hybrid weaves for producing small cooling channel cross sections. FIGS. 5a and 5b show the installation of 2D hybrid weaves for producing large cooling channel cross sections

Finally, FIG. 6 shows a schematic representation of an exemplary 3D hybrid fiber composite for introduction into a CMC prepreg laminate.

FIG. 1 a shows a photograph of a CMC prepreg laminate before the sintering process. To recognize the is

Basic structure 1, on which the prepregs 2 are deposited in layers during the lamination process. Perpendicular to the level of

Layers can be seen as vertical lines, the introduced placeholder in the form of micro-hoses 3, whose diameter is specified with 0.5mm to 1.4mm. Figure lb shows the finished turbine component, according to the Sin ^¬ enlargement process. The viewing angle is rotated by 90 °, you can now see from above along the former placeholder, the micro-tube. To recognize this is where the placeholder 3 in the laminate 2 was now a cooling channel 5 is formed. The finally sintered CMC component 4 has reinforcing fibers 6 which are stable to the conditions of sintering (pressure, temperature). FIGS. 2a to 2d show the incorporation of polymeric channel structures into the CMC prepreg laminate, which can be produced by means of injection molding. Figure 2a shows the first method ^¬ step in which the base structure 6 - a so-called "core structure" -. Launched the CMC prepreg layers 7 are thus laminated on the interface 8 between the single ^¬ NEN CMC prepreg layers can also be seen. in this embodiment of the invention is then as shown in Figure 2b, a placeholder 9 nalstruktur in the form of an injection molded Ka pressed into the already formed CMC prepreg laminate a ^¬ and in the basic structure 6 into the corresponding Wells 10 anchored.

Figure 2c shows - always in cross-section - further CMC prepreg layers of the CMC prepreg laminate 7, ie conventional layers of CMC prepreg, as described for example in WO 2016/159933 AI ^{¬ written} outside the Platzhalter 9, so that the place ^¬ holder 9 is inside the formed CMC prepreg laminate 7, is located. After drying of the CMC prepreg laminate 7, the basic structure can be removed structural ^¬ 6 for the debinding and sintering process. This results in a CMC prepreg laminate 7 with a placeholder 9, as shown in Figure 2d.

The cooling channel structure shown here has openings 11 where the CMC prepreg laminate 7 rests on the base structure 6 and laterally.

Figures 3a and 3b show the formation and incorporation of hybrid fiber, cords and / or tapes.

Here thicker sacrificial fibers are intertwined example 12 with thin ^¬ ren ceramic fibers 13 and result in a hybrid fiber cord 14, as shown in Figure 3a. 3b shows how the hybrid fiber cord is introduced 14 into the CMC prepreg laminate 7, for example, in addition to the square ^¬ holder 9 of Figure 1 and / or 2 is shown. The cross-sectional view shown in Figure 3b goes through the CMC prepreg laminate 7 and by the inserted hybrid fiber cord 14.

Figures 4a and 4b show by way of example a 2D hybrid fabric 15 of ceramic fibers 13 and sacrificial fibers 12 in a CMC prepreg laminate 7, wherein the sacrificial fiber 12 has only a small cross-section of, for example, 1500 denier.

FIG. 4 a shows a 2-dimensional fiber fabric made of ceramic, for example oxidic, fiber 13, which is laid both in the x and y directions. In this 2-dimensional tissue is still a sacrificial fiber 12 is woven into the y-direction. FIG. 4 b shows an exemplary layer of a hybrid fabric 15 in a CMC prepreg laminate 7.

FIG. 5 shows another example of a hybrid weave 15 in which the sacrificial fiber 12 has a substantially larger cross-section than the ceramic fiber 13. As in FIG. 4 a, a woven fabric of ceramic fiber 13 is woven in the x-direction and in the y-direction, wherein a fat sacrificial fiber 12 a after the other 12 b, 12 c, ... is once covered by the ceramic fabric 13 like a wave and alternatively once on the fabric 13 comes to rest. For example, a "fat" sacrificial fiber is a 10,000 denier roving carbon fiber.

FIG. 5b again shows the incorporation of this hybrid tissue into a CMC prepreg laminate 7, the thick sacrificial fibers 12 being visible here.

FIG. 6 shows an exemplary hybrid fiber composite 16 which is formed by interweaving three fibers 12, 13 and 17. It is freely selectable, where in the composite, the sacrificial fibers 12 and where the ceramic fibers 13 are, as well as the choice of the third fiber 17 as a sacrificial fiber or ceramic fiber, because the composite 16 by producing the sintered CMC Component is stable even after removing the sacrificial fibers.

The production of a hybrid fiber composite takes place, for example, via the braiding process. In this case, oxide ^¬ ical ceramic fibers can also be processed with carbon fibers. The carbon fibers, in turn, may burn out during the temperature treatment and create a fine channel network for cooling a component. For this production method, for example, the ceramic matrix for producing the CMC turbine component is subsequently infiltrated into the SD molding, for example via a transfer molding process. In this case, in the final CMC turbine component can be seen that at least one cooling channel or at least a portion of a cooling channel is supplemented with the Ver ^¬ reinforcing fibers of the CMC component to a pattern.

The present invention provides a turbine component ^¬ will be unveiled that has nalstrukturen on fine and complex Kühlka-. This cooling channel structures are produced in the CMC turbine component without these mecha nically ^¬ tiring process, such as etching, milling, cutting, etc. is subjected. This can be seen, for example, on the inner walls of the cooling ^¬ channels.

Claims

claims 1. CMC turbine component, which is composed at least in part of a ceramic matrix composite material by means of a lamination process, with placeholders in the CMC prepreg, a CMC prepreg precursor and / or the CMC prepreg layers formed from CMC prepreg layers. Prepreg laminate before and / or during the Laminating be introduced, which are removable during sintering of the turbine component by decomposition and / or evaporation and leave defined voids in the CMC prepreg laminate, which are used as cooling channels. 2. CMC turbine component according to claim 1, which is a turbine blade or a turbine blade. 3. CMC turbine component according to one of the preceding Ansprü ^¬ che, wherein at least one cooling channel or a part of a cooling ^¬ channel complemented with at least one present in the CMC turbine component reinforcing fiber or at least a portion of such a reinforcing fiber to a pattern. 4. CMC turbine component according to one of the preceding Ansprü ^¬ che, wherein at least one cooling channel or at least a portion of a cooling channel with at least one reinforcing fiber or at least a portion of a reinforcing fiber of the CMC component results in a braid and / or weave pattern. 5. CMC turbine component according to one of the preceding Ansprü ^¬ che, wherein at least one cooling channel or a part of a cooling ^¬ channel with at least one reinforcing fiber or a part of a reinforcing fiber results in a cord. 6. CMC turbine component according to one of the preceding Ansprü ^¬ che, wherein at least one cooling channel at least partially meanders meandering through the CMC component. 7. CMC turbine component according to one of the preceding Ansprü ^¬ che, wherein the inner walls of the cooling channels have no sharp Kan ^¬ th and / or cut-off reinforcing fibers. 8. CMC turbine component according to one of the preceding Ansprü ^¬ surface, wherein in the interior of the CMC turbine component is a cooling ^¬ structure, which comprises at least one cooling channel or a part of a cooling channel, which has a diameter in Be ^¬ rich from lOOym to 3 mm , 9. A method for producing a CMC turbine component, wherein in one first process step CMC prepreg layers are laminated to a Grund ^¬ structure; in one following method step placeholder are introduced into the CMC prepreg laminate; in one on it following sintering process step, the placeholders are removed by debindering and / or sintering and the CMC turbine component is sintered. 10. The method of claim 9, wherein in a process step prior to the sintering process step, further CMC prepreg layers are laminated to the blank-mounted CMC prepreg layers. 11. The method according to any one of claims 9 or 10, wherein as a dummy micro hoses and / or injection-molded channel ^¬ structures based on organic, inorganic and / or organometallic polymers are introduced into the not yet sintered CMC prepreg laminate. 12. The method according to any one of claims 9 to 11, wherein the wildcards are used as sacrificial fibers in the form of a hybrid fiber cord, hybrid fiber fabric and / or hybrid fiber composites. 13. The method according to claim 12, wherein a carbon fiber is used as the sacrificial fiber. 14. The method according to any one of claims 12 or 13, wherein the sacrificial fiber is a carbon fiber having a diameter range of 500 to 15 000 denier used.