Sandwich component and method for manufacturing a sandwich component

Abstract

A sandwich component is provided comprising a first face layer assembly (22), a core assembly (26) made of C / C-SiC, a second face layer assembly (24), wherein the core assembly (26) is located between the first face layer assembly (22) and the second face layer assembly (24), and at least one interface area (16a, 16b; 42) for force transmission, characterized in that the at least one interface area (16a, 16b; 42) comprises a tube element (44) or rod element made of C / C-SiC, which is connected to the core assembly (26).

Description

[0001] The invention relates to a sandwich component comprising a first face layer assembly, a core assembly made of C / C-SiC, a second face layer assembly, wherein the core assembly is located between the first face layer assembly and the second face layer assembly, and at least one interface area for force application.

[0002] The invention further relates to a method for manufacturing a sandwich component comprising a first cover layer device, a core device, a second cover layer device and at least one interface area.

[0003] The invention is based on the objective of providing a sandwich component of the type mentioned, in which optimized force transmission can be achieved at the at least one interface area.

[0004] This problem is solved in the sandwich component mentioned at the outset according to the invention by the fact that the at least one interface area comprises a tube element or rod element which is made of C / C-SiC and which is connected to the core device.

[0005] The tube element or rod element forms a C / C-SiC interface to the C / C-SiC core unit.

[0006] This interface is thermally neutral with respect to the core unit. This prevents even the smallest stresses and distortions.

[0007] No adhesive or similar material is required. This prevents outgassing or other material changes, especially under a vacuum atmosphere (such as in space).

[0008] Shear stresses can be safely transferred and introduced into the core device; this results in a mechanically good connection at the at least one interface area to the core device for force dissipation.

[0009] The C / C-SiC material provides high temperature resistance.

[0010] The sandwich component is easy and inexpensive to manufacture because individual components can be produced.

[0011] A connection between the core device and the tube element or rod element with the same microstructure can be established by siliconizing the core device and the tube element or rod element, including the connection area between them (possibly including the first cover layer device and / or the second cover layer device).

[0012] A precise and therefore mechanically robust connection can be achieved between the pipe element or rod element and the core device at at least one interface area.

[0013] The tube element or rod element is a region of the sandwich component that is geometrically identifiable. It is not a separate component, but rather an element (made of C / C-SiC) that is integrally connected to the core structure (and was, for example, a separate precursor during manufacturing).

[0014] It is advantageous if at least one of the following is provided: - the pipe element or rod element is integrally connected to the core device; - the pipe element or rod element is connected to the core device by in-situ joining; - the tube element or rod element is connected to the core device without an intermediate layer, wherein in particular the tube element or rod element, the core device and a connection area have the same microstructure; - the tube element or rod element forms a material composite of C / C-SiC and / or a ceramic material composite with the core device.

[0015] The tube or rod element and the core assembly form a type of composite material made of C / C-SiC with the same (ceramic) microstructure. Microscopically, in the solution according to the invention, the microstructure at the connection area between the core assembly and the tube or rod element cannot (generally) be distinguished from the microstructure of the core assembly or the microstructure of the tube or rod element.

[0016] In particular, there is no adhesive layer or the like, so that no outgassing can take place, and no foreign material is introduced into the C / C-SiC on the finished component.

[0017] It is particularly advantageous if the fiber orientation in the tube or rod element is the same as the fiber orientation in the core assembly, at least at one connection point between the core assembly and the tube or rod element. This allows forces at the at least one interface point to be effectively transferred into the core assembly. Furthermore, this results in a substantially identical coefficient of thermal expansion for the tube or rod element and the core assembly. Consequently, there is no uneven deformation of the core assembly and the tube or rod element during temperature changes.

[0018] It is particularly advantageous if the tube or rod element has a height that is at least as high as the core assembly, and especially at least as high as the sandwich component comprising the first face sheet assembly, the core assembly, and the second face sheet assembly. This provides an effective C / C-SiC interface with the advantages described above.

[0019] In one embodiment, the pipe element or rod element projects beyond the first cover layer assembly and / or the second cover layer assembly. This can be advantageous for certain connection structures.

[0020] In one embodiment, at least one central element is arranged on the pipe element, in particular with at least one of the following: - the height of at least one central element is less than the height of the pipe element; - the at least one central element sits in a recess of the pipe element; - the at least one central element is connected to the pipe element by in-situ joining; - a fiber orientation in the at least one central element corresponds to the fiber orientation in the pipe element; - the at least one central element has a first end face which can be used as a mounting surface, and has an opposite second end face which can be used as a mounting surface.

[0021] Such a central element is advantageous, for example, when screws or bolts are to be used that have a length less than the thickness of the sandwich component. The central element forms a type of insert on the tube element and serves as a mounting element for screws, bolts, or the like.

[0022] If the height of at least one central element is less than the height of the pipe element, corresponding screws or bolts or the like with reduced height can be used.

[0023] In particular, the central element (at least one) sits in a recess of the pipe element to achieve, for example, a reduction in its height. This allows for a precise and mechanically robust connection between the central element and the pipe element. (In principle, the central element can also fill the entire pipe element. In this case, the combination of pipe element and central element ultimately forms a rod element.)

[0024] The at least one central element is connected to the tube element in the sandwich component by in-situ joining and, in particular, is siliconized together with the core assembly (optionally also in a second siliconization step). This achieves the same advantages for the transition between the central element and the tube element as described above for the transition between the tube element and the core assembly. In particular, thermal neutrality exists between the at least one central element and the tube element. No adhesive or similar material is required, so no outgassing or other material changes can occur. A mechanically and thermally robust connection to the tube element, and thus to the core assembly, is achieved for the reliable transmission of shear stresses. High-temperature resistance is achieved with simple and cost-effective manufacturing.

[0025] It is also advantageous if the fiber orientation in the at least one central element corresponds to the fiber orientation in the pipe element in order to achieve effective force transmission and thus also force dissipation.

[0026] Because the at least one central element has a first end face and a second end face, at least one contact surface, and in particular two contact surfaces, are provided, which can be used, for example, for a nut, a washer, or the like. Advantageously, the at least one central element is connected to the tube element in the same way as the tube element is connected to the core device, with the same microstructure in C / C-SiC being provided in particular.

[0027] In one embodiment, the pipe element or rod element and / or at least one central element attached to the pipe element has at least one flange. This flange rests, for example, against the first or second cover layer assembly. It is connected to the corresponding cover layer assembly, particularly by in-situ joining. This provides additional support, especially against compressive or tensile forces.

[0028] Furthermore, it is advantageous if at least one application recess, in particular a continuous application recess, is arranged at the at least one interface area, especially with at least one of the following: - at least one application recess is located in the rod element; - the at least one application recess is located in a central element which is arranged on the pipe element; - the at least one application recess has an orientation that is parallel or at an acute angle of less than 30° to a vertical direction of the sandwich component; - at least one application recess serves to accommodate a mounting element.

[0029] The application recess is used in particular for mounting the sandwich component to a corresponding support or for mounting one or more elements to the sandwich component, in which case the sandwich component acts as the support. For example, an application recess serves to guide a bolt or screw.

[0030] It may be provided that at least one application recess is located in the rod element, or, if a central element is provided, in the central element.

[0031] Preferably, for optimized force transmission, an application recess is oriented with an axis parallel to or at an acute angle of less than 30° to a vertical direction of the sandwich component. The at least one application recess serves in particular to receive a mounting element for mounting the sandwich component or for mounting another component to the sandwich component.

[0032] It is particularly advantageous if the core structure has a 2D lattice structure with cells, which is primarily manufactured using strips. This allows for simple production of the core structure. An optimized core structure for a sandwich component with face sheets (face skins) can then be provided.

[0033] The cells can, for example, have a hexagonal structure. In a manufacturing-technically simple embodiment, the cells have a rectangular shape, and in particular a square shape. A square shape provides good homogeneity with regard to force absorption. From a manufacturing perspective, such a core assembly can be easily produced using strips, which are manufactured individually and then joined together, particularly by interlocking. The connection between the strips is achieved, in particular, by positive locking.

[0034] Furthermore, it is advantageous if at least one of the following is provided: Cells at the at least one interface area have smaller dimensions than cells that are at a certain distance from the at least one interface area, with a cell reduction in the ratio of 1:4 at the interface area in particular. nis done, where n is a natural number; - Cells at least one interface area are provided with a filling structure made of C / C-SiC.

[0035] If cells at the at least one interface area ("near cells") have smaller dimensions than cells ("far cells") located at a certain distance from the at least one interface area, then a kind of cell density can be achieved at the interface area. This generally results in increased material density at the at least one interface area, leading to increased mechanical strength and stiffness.

[0036] In an advantageous embodiment, the cell size is reduced by a ratio of 1:4 at the interface area. n This means that, with regard to a long-distance cell, a subdivision of an actual long-distance cell into 4 is possible in the local area. nNear cells are created. This subdivision is easily achieved by using additional ridges in the area of ​​at least one interface region. In an advantageous embodiment, n = 1.

[0037] Material compaction at at least one interface area is also achieved when cells are filled with a C / C-SiC structure. This optimizes force transmission and allows for the absorption of increased forces. The mechanical connection of the core assembly to the interface area is improved by increasing the contact surface.

[0038] It is advantageous if at least one of the following is provided: - the C / C-SiC filling structure is manufactured in-situ with the core device and the at least one interface area; - the filling structure comprises at least one bar profile and in particular a plurality of bar profiles in a cell; - the filling structure comprises a 2D woven fabric or 2D knitted fabric or 2D crocheted fabric; - the filling structure comprises a wound 2D woven fabric or 2D knitted fabric or 2D crocheted fabric; - the filling structure comprises a stack of layers of 2D woven or 2D knitted fabrics or 2D crocheted fabrics; - the filling structure includes short fibers; - the filling structure includes monolithic areas, which are produced in particular by means of joining paste; - The material density of the core device is higher at the at least one interface area than at a certain minimum distance from the at least one interface area.

[0039] Several options exist for the filling structure. In particular, the C / C-SiC filling structure is produced in-situ with the core assembly and the at least one interface region. If the core assembly and the at least one interface region (with the tube element or rod element) are siliconized, then the filling structure is preferably siliconized as well.

[0040] In one embodiment, the infill structure comprises at least one bar profile and, in particular, a plurality of bar profiles within a cell. A cell can be made mechanically more stable with a bar profile. When multiple bar profiles are used, their arrangement depends on the application. A bar profile can be solid ("filled") or hollow.

[0041] The filling structure can also include a 2D woven or 2D knitted fabric.

[0042] For example, the filling structure comprises a wound 2D woven fabric or 2D knitted fabric or 2D crocheted fabric, which has then been silicified accordingly.

[0043] It may also be provided that the filling structure comprises a stack of layers of 2D woven or 2D knitted fabrics, which are appropriately siliconized.

[0044] It is also possible that the filler structure comprises short fibers, which were bonded together, in particular, using a bonding paste. The bonding paste is silicon-based.

[0045] The infill structure can also include monolithic areas, which are often produced using bonding paste. It is also possible that, for example, when using bar profiles, gaps between the layers were filled with bonding paste. In the sandwich component, a bonding paste area then becomes a C / C-SiC layer.

[0046] In particular, the material density of the core device at the at least one interface area is higher due to the filling structure than at a certain minimum distance to the at least one interface area.

[0047] It is specifically intended that the at least one interface area serves as a connection area for the sandwich component (in an application) and / or for a component on the sandwich component, and in particular for receiving at least one mounting element. An interface area allows, in a sense, the connection of the sandwich component to the outside world (such as to a satellite structure).

[0048] According to the invention, a method of the type mentioned at the outset is provided in which a precursor of the core device is produced from C / C elements, a recess is produced on the precursor of the core device or the core device for an interface area, a precursor for a tube element or rod element, which is made of C / C or C / C-SiC, is positioned in the recess, and siliconization is carried out with an in-situ joining of the tube element or rod element to the core device.

[0049] The C / C elements for the precursor of the core device as well as the precursor for the tube element or rod element are in particular open-porous.

[0050] Through appropriate silicification, a uniform microstructure is achieved.

[0051] It is generally intended that during the siliconization of the tube or rod element, the core assembly (possibly including any filler structure) is also siliconized. This is, in effect, an integrated manufacturing process for the core assembly with the in-situ joined tube or rod element (and, if applicable, the central element). It is also possible, for example, that the core assembly has already been siliconized and consists of C / C-SiC. In this case, a siliconization ("initial siliconization") of the tube element (possibly including the central element) or the rod element is carried out, particularly with a joining area made of joining paste. The core assembly is then siliconized again. (The entire assembly is siliconized.) In particular, further carbide formation occurs at the carbon phases (e.g., of the joining paste). This also creates an in-situ bond between the core assembly and the tube or rod element.This procedure is particularly suitable for repairs or when an interface area needs to be created on an existing sandwich component. Specifically, the recess is then created on the core element. (If the core element's precursor and the rod or tube element's precursor are siliconized together, then the recess is advantageously created on the core element's precursor.)

[0052] A core device, or a pipe element or rod element, which is made of C / C-SiC and is later re-siliconized, can be considered a precursor.

[0053] The recess is first produced on the precursor of the core device (possibly with a filling structure) in order to then position the precursor for the tube element or rod element in the recess, possibly using joining paste.

[0054] It is also possible that the tube or rod element is already made of C / C-SiC. In this case, it undergoes re-siliconization upon connection with the core unit. The general principle is that the core unit (possibly including filler structures) and the tube or rod element (possibly including the central element) are completely siliconized.

[0055] In principle, the following combinations are possible: a C / C core element precursor is combined with a C / C tube or rod element precursor (1). Preferably, an adhesive paste is introduced between these elements. Another possibility (2) is that the core element or the corresponding precursor is already made of C / C-SiC and is combined with a C / C tube or rod element. Another possibility is that a core element precursor is made of C / C and the tube or rod element intended for combination is made of C / C-SiC (3). Another possibility (4) is that a C / C-SiC core element precursor is used, and a C / C-SiC tube or rod element precursor, and in particular, an adhesive paste, is provided.In options (1) to (4), the entire combination of core assembly and tube element (possibly with central element) and rod element is siliconized to produce a uniform C / C-SiC joining area. Areas that have already been siliconized are siliconized again to create the final joint.

[0056] If the precursor of the core device or the tube element or rod element is already made of C / C-SiC, the production is advantageously adjusted so that enough free carbon phases are present (which are also accessible during siliconization) to achieve sufficient carbide formation during the subsequent siliconization (for the production of the joining area).

[0057] This is followed by silicification to produce a uniform material.

[0058] If necessary, precursors of the face layer devices are siliconized in order to then produce the sandwich component with face layer devices, core device and at least one interface area.

[0059] In particular, a precursor for a central element made of C / C or C / C-SiC is positioned on the precursor for the tube element, especially using an joining paste. This allows for the provision of an additional central element, which, for example, has at least one application recess. This results in a differential manufacturing process in which individual components can be manufactured separately, then positioned in the C / C state (especially with open porosity) or already as a C / C-SiC element, and subsequently siliconized, resulting in a uniform C / C-SiC material, also for a connection area between the tube element or rod element and the core device.

[0060] In particular, the precursor for the rod or tube element is manufactured or provided with at least one application recess, and especially a continuous application recess, or the tube or rod element itself is provided with at least one application recess. This allows for the simple creation of an application recess in the finished sandwich component, for example, for a screw or bolt. While it is also possible to subsequently create such an application recess at the at least one interface area, this is very complex due to the carbide ceramic component in the sandwich component. Preparing the precursor for the tube or rod element simplifies manufacturing.

[0061] It is particularly advantageous if the precursor to the core device is manufactured as a 2D lattice structure with cells, whereby the cell density is increased as the number of cells per unit area at the recess. This results in improved force dissipation.

[0062] Improved force dissipation is also achieved when the core element's precursor is manufactured as a 2D lattice structure with cells, where cells in the recess area are filled with a C / C or C / C-SiC structure that is siliconized along with the core element and the tube or rod element. This results in reliable shear stress transmission.

[0063] A precursor of the filling structure is, in particular, open-porous and made of C / C.

[0064] It is advantageous if the recess is produced as a cylindrical recess. This results in simple geometric definition. It is produced, for example, using a diamond hollow drill. It can be produced separately on the core preparation and separately on the face sheet preparation, or a sandwich component precursor with core preparation and face sheet preparation is already assembled (especially using bonding compound), and the cylindrical recess is then produced on this assembly by the face sheet preparation and the core preparation.

[0065] In particular, joining paste is used when positioning the precursor of the tube element or the rod element at the recess. The joining paste serves as a carbon precursor to provide carbon at the connection area for siliconization to produce the corresponding C / C-SiC microstructure.

[0066] Furthermore, it is advantageous if at least one of the following is provided: - a precursor of the first deck layer equipment is made from C / C; - a precursor of the second deck layer device is made from C / C; - the first layer assembly and / or the second layer assembly are made of C / C-SiC; - the first cover layer structure and / or the second cover layer structure is silicified along with the core structure during the silicification process; - A precursor of the first cover layer device and / or a precursor of the second cover layer device is positioned on the precursor of the core device using joining paste.

[0067] If a cover layer device made of C / C-SiC is provided, then this can be manufactured in particular integrally with the manufacture of the core device and the at least one interface area.

[0068] The following description of preferred embodiments, in conjunction with the drawings, serves to further explain the invention. The drawings show: Fig. 1 a schematic representation of a sandwich component in the form of an optical bench; Fig. 2 a partial sectional view through a first embodiment of a sandwich component according to the invention; Fig. 3 a sectional view along line 3-3 of the sandwich component according to Fig. 2; Fig. 4 schematic steps of the manufacture of a precursor to a core device for the sandwich component according to Fig. 2; Fig. 5 a top view of an embodiment of a core device, showing different filling structures for cells; Fig. 6 the precursor core device according to Fig. 5 after making a recess to create an interface area; Fig. 7 a schematic sectional view of a precursor for a sandwich component with precursor of a pipe assembly and precursor of a central element (during the manufacturing process); Fig. 8 an embodiment of a precursor of a pipe element with an inserted precursor of a central element (with application recess); Fig. 9 another embodiment of a precursor of a pipe element with an inserted precursor of a central element (without application recess); Fig. 10 a first embodiment of a filling structure; Fig. 11 a second embodiment of a filling structure; Fig. 12 a third embodiment of a filling structure on a cell; Fig. 13 to 15 further examples of filling structures on a cell; Fig. 16 a sectional view of another embodiment of a sandwich component in partial representation; Fig. 17 a sectional view along line 17-17 according to Fig. 16 of the sandwich component according to Fig. 16; and Fig. 18 a schematic sectional view of a manufactured sandwich component with a plurality of interface areas.

[0069] One embodiment of a sandwich component according to the invention is an optical bench 10 ( Fig. 1) The optical bench 10 is used, for example, in a satellite as a carrier for optical elements 12, 14.

[0070] The optical bench 10 (the sandwich component) comprises interface areas 16a, 16b. An interface area 16a, 16b serves to introduce force into the optical bench 10 and in particular as a mounting area.

[0071] The optical bench 10 basically has two types of interface areas, namely the interface areas 16a, which serve to mount corresponding holders 18, via which the optical bench 10 can be mounted on a support for the optical bench 10.

[0072] Furthermore, there are interface areas 16b where components can be mounted on the optical bench 10 itself, and in particular the optical elements 12, 14 can be mounted.

[0073] An embodiment of a sandwich component according to the invention 20 ( Fig. 2, Fig. 3) comprises a first layer assembly 22, a second layer assembly 24, and a core assembly 26. The first layer assembly 22 is connected to the core assembly 26 at a first side 28 of the core assembly 26. The second layer assembly 24 is connected to the core assembly 26 at a second side 30 of the core assembly 26. The second side 30 faces away from the first side 28. The core assembly 26 is located between the first layer assembly 22 and the second layer assembly 24.

[0074] The first cover layer assembly 22 and the second cover layer assembly 24 form cover skins for the core assembly 26.

[0075] Core device 26 is made of C / C-SiC. The material of core device 26 comprises silicon carbide (SiC) with carbon fibers and a free carbon phase, wherein the carbon fibers are embedded in a C matrix (C / C), which in turn is embedded in a SiC matrix.

[0076] The first cover layer assembly 22 and the second cover layer assembly 24 are made of a fiber-reinforced composite material. In particular, they are also made of C / C-SiC.

[0077] The core device 26 is designed as a lattice structure 32. It comprises a plurality of cells 34. Each cell has a wall 36 (made of C / C-SiC) and an interior space 38, which is surrounded by the wall 36. The lattice structure 32 is, in particular, a 2D lattice structure. R→=n1a1→+n2a2→ with the primitive vectors a1→,a2→, which span the grid.

[0078] A distance direction 40 between the first cover layer device 22 and the second cover layer device 24 lies perpendicular to these primitive vectors. a1→ and a2→.

[0079] In one embodiment, the grid structure 32 is a rectangular grid, and in particular a square grid, in which a cell 34 has the same length with respect to the primitive vector. a1→ and the primitive vector a2→ exhibits, where the primitive vectors are perpendicular to each other.

[0080] Adjacent cells 34 are in particular separated from each other and their interiors 38 are not connected to each other.

[0081] Cells 34 are empty at least outside the interface area 42 (with a minimum distance to the interface area 42) with respect to the interior 38.

[0082] The first side 28 and the second side 30 lie on opposite end faces of the wall 36. The first cover layer assembly 22 and the second cover layer assembly 24 are supported on these end faces of the walls 36 of the cells 34.

[0083] A pipe element 44 made of C / C-SiC is arranged at the interface area 42.

[0084] In the illustrated embodiment, the pipe element 44 has a hollow cylindrical shape with a cylinder axis 46 which is perpendicular to the primitive vectors. a1→,a2→ The tube element 44 has a shell wall 48 made of C / C-SiC. The tube element 44 is connected to the core unit 26, forming a ceramic material connection made of C / C-SiC. Between the core unit 26 and the shell wall 48, a uniform microstructure for the C / C-SiC exists at the connection point, and a single block of C / C-SiC material is formed from the core unit 26 to the transition area and the shell wall 48.

[0085] The tube element 44 is connected to the core assembly 26 by in-situ joining and is manufactured as a C / C-SiC element. This is explained in more detail below. The core assembly 26 and the shell wall 48 are siliconized together to create the in-situ joining.

[0086] In one embodiment, the fiber orientation with the shell wall 48 is the same as the fiber orientation at the core device 26.

[0087] The pipe element 44 as a C / C-SiC element is produced at the core device 26 during siliconization.

[0088] The tube element 44 has a height in the cylinder axis 46 which is at least as high as a height H of the sandwich component 20. The tube element 44 extends over the entire core assembly 26 with respect to the spacing direction 40 and also over the first cover layer assembly 22 and the second cover layer assembly 24.

[0089] In the illustrated embodiment, the pipe element 44 projects beyond the first cover layer device 22 with a region 50.

[0090] The pipe element 44 is connected to a region 52 of the first cover layer device 22 and to a region 54 of the second cover layer device 24. These regions 52, 54 surround, in particular, circular recesses on the first cover layer device 22 and the second cover layer device 24, respectively.

[0091] Furthermore, the pipe element 44 is connected to the walls 36 of cells 34 at the interface area 42 and to longitudinal sides 56 of the walls 36, which are oriented parallel to the spacing direction 40 (parallel to the cylinder axis 46). The longitudinal sides 56 lie transversely and, in particular, perpendicular to the aforementioned end faces of the walls 36.

[0092] The connections are made by in-situ joining, as mentioned above.

[0093] Furthermore, the pipe element 44 can also be connected to filling structures 58 within cells 34 in the area of ​​the interface region 42. This is explained in more detail below. (By connecting, and in particular ceramically connecting, the pipe element 44 to the filling structure 58, a larger joining surface to the core device 26 is provided. Shear loads can be transferred from the wall of the pipe element 44 via the filling structures 58 into the walls 36 of the cells 34. For force transmission, not only the relatively small longitudinal sides 56 of the walls 36 are effective.)

[0094] In one embodiment, a central element 60 is arranged on the tube element 44. Geometrically, the central element 60 can be considered a type of plug positioned on the tube element 44. The central element 60 is made of C / C-SiC and is connected to the tube element 44 by in-situ joining.

[0095] In particular, the fiber orientation at the central element 60 is the same as at the tube element 44.

[0096] The central element 60 has a region 62 which lies in an interior of the pipe element 44.

[0097] The central element 60 has a height 64, which is less than the height H of the pipe element 44. The central element 60 has a first end face 66, which is oriented transversely and, in particular, perpendicularly to the spacing direction 40.

[0098] At the in Fig. In the embodiment shown in 2, the first end face 66 is located above a cover surface of the first cover layer device 22.

[0099] The central element 60 also has a second end face 68 opposite the first end face 66. The second end face 68 lies transversely to the spacing direction 40 and, in particular, perpendicular to it. The second end face 68 lies within the interior of the pipe element 44. The first end face 66 and the second end face 68 are parallel to each other. This ensures, for example, a secure fastening of a flange with a bolt or with a bolt and nut.

[0100] The first end face 66 and the second end face 68 provide usable contact areas, for example for a nut or a washer or the like.

[0101] The central element 60 has (at least) one continuous recess 70. The recess 70 extends between the first end face 66 and the second end face 68. The recess 70 is an application recess, for example to accommodate a bolt or the like.

[0102] In the illustrated embodiment, the application recess 70 extends parallel to the spacing direction 40.

[0103] In one embodiment, an application recess 70 is provided with a thread, and in particular an internal thread. This allows, for example, direct screwing.

[0104] The height 64 of the central element 60 and its position on the pipe element 44 depend on the application. In principle, several central elements 60 can also be provided on one pipe element 44.

[0105] Force is introduced (and dissipated) into the core device 26 of the sandwich component 20 via the central element and the pipe element 44.

[0106] In one embodiment, material compaction is carried out on the core device 26 in the area of ​​the interface area 42.

[0107] This can be achieved in particular through two measures, which can be implemented alternatively or combined with each other.

[0108] In measure (1), a reduction in cell size 72 takes place in the area of ​​the interface area 42. Cells 34 at a certain distance from the interface area 42 are larger than cells 74 at or in the vicinity of the interface area 42. The cells 74 can be described as near cells for the interface area 42, and cells at a sufficiently large distance from the interface area 42 as far cells.

[0109] The above grid structure applies to the distant cells.

[0110] The following applies to the local cells: R→'=n1n3a1→+n2n4a2→ n3 and n4 are greater than or equal to 2.

[0111] At the in Fig. In the embodiment shown in Figure 3, n3 and n4 are equal and equal to 2. This means that a near cell 74 occupies one quarter of a far cell, or that at the interface area 42 a far cell is divided into four near cells 74.

[0112] This is achieved by providing additional walls 76a, 76b between walls 36 of remote cells.

[0113] The number of walls for connection with the pipe element 44 is thereby increased at the interface area 42.

[0114] A further measure (2) to increase the material density at the interface area 42 is the provision of filling structures 58. Filling structures 58 are arranged in cells 34, which in particular border the pipe element 44 (its outer wall 48) or are in the vicinity thereof. In particular, such filling structures 58 are arranged in adjacent cells 74.

[0115] The filling structures 58 are also made of C / C-SiC. (In particular, precursors of the filling structures 58 made of C / C are used in their manufacture, and the filling structures 58 made of C / C-SiC are produced during the siliconization of the entire structure, including the precursors of the core device 26.)

[0116] In one embodiment ( Fig. 3) A filling structure 58 for a near cell 74 is produced from a wound C-woven fabric or C-knitted fabric, in particular with a 2D fiber structure. A winding axis 78 lies parallel to the spacing direction 40 or the cylinder axis 46.

[0117] In the illustrated embodiment, each near cell 74 adjacent to the tube element 44 is provided with the corresponding filling structure 58. Furthermore, cells 80 adjacent to such near cells 74 are also provided with the filling structure 58.

[0118] Further examples of filling structures are explained below.

[0119] For example, it is also possible that a rod element without an interior is provided instead of a pipe element 44. In this case, no central element 60 is provided. The corresponding rod element can have one or more application recesses, or, depending on the application, it can also be free of application recesses 70.

[0120] In the solution according to the invention, at least one force introduction element is provided in the interface area 42, where force can be introduced (by mounting the sandwich component 20 and / or by further components mounted on the sandwich component). This force introduction element, like the core assembly 26, is made of C / C-SiC and is connected to it by in-situ joining. The force introduction element is the central element 60 with the tube element 44 or the rod element.

[0121] The force introduction element has the same coefficient of thermal expansion as the material of the core device 26 due to the in-situ joining and the material selection. This avoids internal stresses during thermal cycling.

[0122] Adhesives such as polymeric adhesives, which can outgas in principle (and especially in a vacuum atmosphere like in space), do not need to be used. This in turn prevents outgassing from affecting, for example, optical devices 12, 14.

[0123] The interface area 42 has a high temperature resistance, since, for example, no adhesives, metallic inserts or the like are required to achieve the force connection to the core device 26.

[0124] A mechanically optimized connection to the core device 26 is provided, so that shear stresses in particular can be safely transmitted and dissipated.

[0125] The production of the sandwich component 20 (as explained in more detail below) is simple and inexpensive.

[0126] By compacting the core unit 26 in the interface area 42 through cell reduction 42 and / or filling structures 58, the force introduction and force dissipation can be further optimized.

[0127] The pipe element 44 (with central element 60) or correspondingly the rod element is, in a sense, an interface element and serves to fasten or mount application elements such as screws or bolts and to introduce and dissipate forces and moments.

[0128] In one exemplary embodiment, the sandwich component is manufactured as follows: First, a precursor 82 of the core device 26 is produced. For this purpose, C / C plates 84 are first manufactured. (The C / C plates 84 are made of carbon with embedded carbon fibers.)

[0129] First, CFRP plates 86 are produced. These are thin-walled (for example, with a thickness in the range between 0.3 mm and 0.6 mm). These contain carbon fibers 88, for example, in a 0° / 90° orientation or +45° / -45° orientation.

[0130] The CFRP plates 86 are subjected to pyrolysis, resulting in each open-porous C / C plate 84.

[0131] Strips 90 are machined from the C / C plates 84, for example by laser beam cutting or water jet cutting. These strips 90 are provided with slots 92. The corresponding width of a strip 90 then determines the height of the core assembly 26.

[0132] The strips 90 with the slots 92 are joined together, resulting in a precursor to the 2D grid structure 32. This precursor is in Fig. 4 is labelled with 82.

[0133] In the area where an interface area 42 is to be produced, additional strips may be used to produce the near cells 74.

[0134] Precursors of the first deck layer device 22 and the second deck layer device 24 are also manufactured as C / C plates, which in turn are produced from CFRP plates by pyrolysis.

[0135] A typical thickness of such a C / C plate for the first cover layer device 22 or the second cover layer device 24 is 1 mm to 3 mm.

[0136] In one embodiment, a typical cell 34 of the precursor 82 of the core unit 26 has a length and width of 20 mm. These are also typical dimensions for the cells 34 of the core unit 26.

[0137] On the precursor 82 of the core device 26, corresponding cells 94 are provided with a precursor 96 for a filling structure 58.

[0138] In Fig. 5 are different precursors 96 for filling structures shown, whereby these different types can be used, or only one type, or fewer than the four different types shown.

[0139] In one embodiment, a precursor 96 is produced from a wound prepreg 98. The prepreg is, for example, a carbon fabric with phenolic resin. In principle, production from a dry fabric winding with subsequent resin infiltration is also possible.

[0140] In another example, C / C tubes 100 are provided, which are positioned in the corresponding cell 94 and are connected with joining paste 102.

[0141] The joining paste is typically a mixture of carbon powder and phenolic resin, with the exact composition being defined. After the components to be joined have been positioned, the joining paste is cured. For example, it is heated to approximately 130 °C for two hours. This creates a stable precursor structure. This can then be further processed, for example, by drilling and subsequent siliconization. The joining paste is a carbon precursor. A portion of the joining paste undergoes siliconization, forming silicon carbide (SiC), possibly with carbon phases.

[0142] Another embodiment of a filler structure consists of short carbon-based fibers 104 with bonding paste.

[0143] Another embodiment is a braided 3D preform made of C / C 106.

[0144] For the precursors 98, 100, 106, an axis orientation is preferably parallel to the later cylinder axis 46, that is, perpendicular to the primitive vectors.

[0145] During the positioning of the C / C precursor 96 on the precursor 82, the precursor 82 can already be positioned on a precursor of the first cover layer assembly 22 or the second cover layer assembly 24. In particular, the precursor 82 is joined to the precursor of the first cover layer assembly 22 or the second cover layer assembly 24 by means of a joining paste. The joining paste is then cured.

[0146] After positioning the precursors 96 of the filling structure 58, the precursor of the further cover layer assembly can then be applied, for example, using an adhesive paste, so that a precursor of the sandwich structure is achieved. The adhesive paste is then cured.

[0147] A cylindrical recess 108 is then created in an area where a later interface area 42 is planned. This can be done, for example, by drilling with a diamond hollow hole drill.

[0148] This recess 108 is in particular continuously through the precursor of the first deck layer device 22 and the precursor of the second deck layer device 24 and in particular continuously through the precursor 82 of the core device 26.

[0149] In principle, in a manufacturing process the recess 108 can be provided on both a precursor of the cover layer device 22, 24 and on the precursor 82 of the core device 26, or a recess can be provided separately on the precursor 82 of the core device 26 and the precursors of the cover layer devices 22, 24, and a connection can be provided separately, in particular via joining paste with appropriate alignment of the recesses.

[0150] If precursors of filling structures are introduced before the production of the recess 108, then these are partially removed (“drilled out”) in particular during the production of the recess 108 in order to obtain a corresponding surface (“gapless surface”) for the insertion of the precursor 110 for the pipe element 44 or rod element.

[0151] In recess 108 (compare Fig. 7) A precursor 110 for the pipe element 44 or rod element is then positioned precisely and, in particular, by means of joining paste 102. The precursor 110 for the pipe element 44 or rod element is made of C / C.

[0152] When a central element 60 is provided, a precursor 112 of this central element 60 is positioned on the precursor 110 of the pipe element 44. This precursor 112 of the central element 60 is made of carbon steel. The joining paste is hardened after positioning. This is done, for example, by heating to 130 °C for approximately two hours. This creates a stable precursor structure that can be further processed.

[0153] An example of a precursor 110 is in Fig. 8 shown. This is produced by winding C / C prepreg elements with appropriate dimensions and then positioned in the recess 108. This in Fig. The 8 shown precursors already contain the corresponding application recess 70.

[0154] For example, it is also possible ( Fig. 9) to cut out the precursor 110, which is, for example, a rod element, from a corresponding C / C plate. A corresponding application recess, if required, can be produced, for example, by drilling such a precursor 110.

[0155] The predecessor, which was in Fig. As shown in Figure 9, a flange 114 is provided which can be placed on the surface of the corresponding precursor of the cover layer device 22, 24.

[0156] The corresponding arrangement of precursors for the core unit 26, the cover layer units 22, 24 and, if applicable, the filling structures 58, as well as the tube element 44 or rod element and central element 60, are siliconized after assembly and after curing of the joining paste. For example, siliconization is carried out according to the LSI process (Liquid Silicon Infiltration).

[0157] The corresponding precursor combination is infiltrated with liquid silicon.

[0158] The C / C material of the precursors must be porous. This porosity (open porosity) is achieved primarily through pyrolysis. The precursors used are therefore primarily porous C / C precursors.

[0159] For an example of the LSI procedure, reference is made to EP 1 547 992 B1.

[0160] During siliconization, the sandwich component 20 with the core assembly 26 is made of C / C-SiC. The first face layer assembly 22 and the second face layer assembly 24 are also made of C / C-SiC. The filling structures 58 are also made of C / C-SiC. The tube element 44 or rod element and, if applicable, the central element 60 are also made of C / C-SiC; during siliconization, silicon reacts with carbon to form SiC. A free carbon phase typically remains from the carbon that did not react with silicon. Furthermore, the material contains carbon fibers.

[0161] The individual components are joined via an in-situ joining process. The connection areas are siliconized and exhibit the same microstructure as the core unit 26 and the tube element 44, or the rod element and, if applicable, the central element 60 in bulk.

[0162] Above, an embodiment was described in which a joint siliconization of the precursor 82 of the core device 26 and the precursor 110 of the tube element 44 or rod element takes place, optionally with siliconization of the precursor 112 for the central element 60.

[0163] It is also possible that the core device 26 is already manufactured from C / C-SiC, possibly with C / C-SiC filling structures. The recess 108 is already manufactured or is being manufactured.

[0164] The precursor 110 is then inserted for the tube element 44 or rod element, with joining paste positioned between the core unit 26 and the precursor 110. If necessary, the precursor 112 is also inserted for the central element 60. The tube element 44 or rod element, and optionally the central element 60, are then siliconized by siliconizing the joining paste. This creates the corresponding in-situ connection with the core unit 26.

[0165] Such a procedure is particularly advantageous for repairing an interface area 42 or when a corresponding interface area 42 is to be subsequently added to an existing sandwich component.

[0166] One embodiment of a filling structure 58 is a winding 116 ( Fig. 10) made of C / C-SiC. This winding 116 is produced by winding prepreg material.

[0167] The coefficient of thermal expansion (CTE) for such a winding 116 made of C / C-SiC (after siliconization) is approximately zero in all three spatial directions.

[0168] Another example of a fill structure 58 is a layer stack 118 ( Fig. 11) from C / C-SiC layers. This layer stack 118 is produced by stacking 2D woven or knitted layers or 2D knitted layers made of C / C on top of each other. These are made in particular of prepreg.

[0169] The coefficient of thermal expansion of such a layer stack 118 is approximately zero in the lateral directions of the layer stack 118. Perpendicular to this, it is significantly greater than zero.

[0170] The layer stack 118 is positioned within a cell 74 or 34 such that a height direction 120 of the layer stack 118 is parallel to the spacing direction 40. In this height direction 120, the coefficient of thermal expansion is significantly different from zero.

[0171] It is also possible, for example, that the filling structure 122 is monolithic, and may contain short fibers. This monolithic filling structure 122 consists in particular of C / C-SiC.

[0172] The coefficient of thermal expansion in all three directions is particularly different from zero.

[0173] Further embodiments of filling structures 58 are described in the Fig. Figures 13 to 15 show that 34 profile bars 124 are positioned in one cell. The profile bars 124 can be solid or hollow. One wall 126 of the profile bars 124 is made of C / C-SiC.

[0174] These profile bars 124 are manufactured from corresponding C / C profiles by siliconizing with siliconizing the core device 26.

[0175] The arrangement of the profile bars 124 is such that a cylinder axis of the profile bars 124 is parallel to the cylinder axis 46 of the pipe element 44 or bar element, or parallel to the spacing direction 40.

[0176] It can be provided that areas 128 between profile bars 124 are empty or filled. They can, for example, be filled with C / C-SiC. This is produced from bonding paste, especially during siliconization. Precursors of the cylindrical profiles 124 (made of C / C) are positioned in precursors of the cells 34 and fixed in the intermediate areas with bonding paste (as C precursors).

[0177] During silicification, C / C-SiC is formed.

[0178] The number and size of the profile bars 124 within a cell 34 (at the interface area 42) depends on the application.

[0179] In one embodiment, the profile bars 124 are arranged uniformly in rows and columns ( Fig. 13, Fig. 15).

[0180] In accordance with the order Fig. 15 a middle profile bar is provided which touches and is connected to all other outer profile bars.

[0181] In another embodiment of a sandwich component 130 ( Fig. 16, Fig. 17) An interface area 132 is provided, which includes a central element 134 with a plurality of application recesses 136. In the illustrated embodiment, four application recesses 136 are provided. These are arranged in the central element 134.

[0182] The sandwich component 130 includes a tube element 138 which has a flange 139 on the first cover layer device 22 (identical reference numerals are used for identical elements).

[0183] In principle, it is also possible that the central element 134 is equipped with a flange.

[0184] Otherwise, the sandwich component 130 is designed in the same way as the sandwich component 20.

[0185] In Fig. Figure 18 shows a cross-section through an embodiment of a sandwich component, for example for the optical bench 10, which has different interface areas 140, 142, 144 for different connection types. These are arranged in a distributed manner.

[0186] A corresponding core facility 26 with cells 34 is provided.

[0187] In the embodiment according to Fig.No fill structures 58 are shown for corresponding cells 74. Such a fill structure can be provided at interface areas 42 at corresponding cells 74, as described above.

[0188] During the manufacturing process for a sandwich component 10, a bonding paste is used. This paste is a carbon precursor. During siliconization, the bonding paste material is at least partially transformed, resulting in SiC. Free carbon phases may also be present. This is the same material as the material of the (final) core assembly 26 and the (final) tube element 44 or rod element. A microstructure has formed where the bonding paste was previously located. No layer of foreign material remains that could, for example, outgas. The area where the bonding paste was previously located is integrated into the C / C-SiC microstructure at the transition between the core assembly 26 and the tube element 44 or rod element.

[0189] The bonding area created by the use of the joining paste is a ceramic bonding area.

[0190] It is generally intended that if a precursor of the core assembly 26 is made of C / C-SiC and / or a precursor of the tube element 44 or rod element is made of C / C-SiC, a combination is produced, in particular using joining paste, and then (after the joining paste has cured) the entire combination (including, if applicable, the central element and filling structures) is siliconized. Those areas that are already made of C / C-SiC are siliconized again.

[0191] A uniform structure made of C / C-SiC, including the joining area, is then achieved. Reference symbol list 10 optical bench 12 optical element 14 optical element 16a, 16b Interface area 18 holders 20 Sandwich component 22 first deck layer setup 24 second deck layer equipment 26 Core facility 28 first page 30 second page 32 Grid structure 34 cells 36 wall 38 Interior 40 Distance direction 42 Interface area 44 pipe element 46 cylinder axle 48 Mantle wall 50 area 52 area 54 area 56 Long side 58 Fill structure 60 Central element 62 area 64 Height 66 first front 68 second front 70 Application recess 72 Cell reduction 74 Near cell 76a, 76b wall 78 Winding axis 80 cells 82 Precursor Core Facility 84 C / C plate 86 CFRP plate 88 Carbon fiber 90 bar 92 slots 94 cells 96 Precursors 98 wound prepreg 100 tubes 102 Joining Paste 104 Short fiber 106 braided preform 108 Exclusion 110 Precursors 112 Precursors 114 Flange 116 windings 118 stacks of layers 120 Altitude 122 monolithic filling structure 124 profile bar 126 wall 128 area 130 sandwich components 132 Interface area 134 Central element 136 Application Exclusion 138 pipe element 139 Flange 140 interface area 142 Interface area 144 Interface area QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1 547 992 B1

[0159]

Claims

[1] Sandwich component comprising a first face layer assembly (22), a core assembly (26) made of C / C-SiC, a second face layer assembly (24), wherein the core assembly (26) is located between the first face layer assembly (22) and the second face layer assembly (24), and at least one interface area (16a, 16b; 42) for force transmission, characterized by , that the at least one interface area (16a, 16b; 42) comprises a tube element (44) or rod element made of C / C-SiC, which is connected to the core device (26). [2] Sandwich component according to claim 1, characterized by at least one of the following: - the pipe element (44) or rod element is integrally connected to the core device (26); - the tube element (44) or rod element is connected to the core device (26) by in-situ joining; - the tube element (44) or rod element is connected to the core device (26) without an intermediate layer, wherein in particular the tube element (44) or rod element, the core device (26) and a connection area have the same microstructure; - the tube element (44) or rod element forms a material composite of C / C-SiC and / or a ceramic material composite with the core device (26). [3] Sandwich component according to claim 1 or 2, characterized by , that a fiber orientation in the tube element (44) or rod element is the same as a fiber orientation at the core device (26) at least at a connection area between the core device (26) and the tube element (44) or the rod element. [4] Sandwich component according to any of the preceding claims, characterized bythat the tube element (44) or rod element has a height which is at least as great as the height of the core device (26), and in particular at least as great as the height of the sandwich component with the first cover layer device (22), the core device (26) and the second cover layer device (24). [5] Sandwich component according to claim 4, characterized by , that the pipe element (44) or the rod element projects beyond the first cover layer device (22) and / or the second cover layer device (24). [6] Sandwich component according to any of the preceding claims, characterized by , that at least one central element (60) is arranged on the pipe element (44), in particular with at least one of the following: - the height of the at least one central element (60) is less than the height of the pipe element (44); - the at least one central element (60) sits in a recess of the pipe element (44); - the at least one central element (60) is connected to the pipe element (44) by in-situ joining; - a fiber orientation in the at least one central element (60) corresponds to the fiber orientation in the tube element (44); - the at least one central element (60) has a first end face (66) which can be used as a mounting surface and has an opposite second end face (68) which can be used as a mounting surface. [7] Sandwich component according to any of the preceding claims, characterized by that the pipe element (44) or the rod element and / or at least one central element (60) which is attached to the pipe element (44) has at least one flange (139). [8] Sandwich component according to any of the preceding claims, characterized by, that at least one application recess (70), in particular a continuous application recess (70), is arranged on the at least one interface area (42), in particular with at least one of the following: - the at least one application recess (70) is located in the rod element; - the at least one application recess (70) is located in a central element (60) which is arranged on the pipe element (44); - the at least one application recess (70) has an orientation which is parallel or at an acute angle of less than 30° to a height direction of the sandwich component (20); - the at least one application recess (70) serves to accommodate a mounting element. [9] Sandwich component according to any of the preceding claims, characterized by , that the core device (26) has a 2D grid structure with cells (34), which is produced in particular via strips (90). [10] Sandwich component according to claim 9, characterized by at least one of the following: - Cells (74) at the at least one interface area (42) have smaller dimensions than cells (34) which are at a certain distance from the at least one interface area (42), wherein in particular at the interface area (42) there is a cell reduction in the ratio 1 : 4 n is done, where n is a natural number; - Cells (74) at which at least one interface area (42) is provided with a filling structure (58) made of C / C-SiC. [11] Sandwich component according to claim 10, characterized by at least one of the following: - the filling structure (58) made of C / C-SiC is produced in situ with the core device (26) and the at least one interface area (42); - the filling structure (58) comprises at least one profile bar (124) and in particular a plurality of profile bars (124) in a cell (74); - the filling structure (58) comprises a 2D woven fabric or 2D knitted fabric or 2D knitted fabric; - the filling structure (58) comprises a wound 2D woven fabric or 2D knitted fabric or 2D crocheted fabric; - the filling structure (58) comprises a stack of layers (118) of 2D woven or 2D knitted fabrics or 2D crocheted fabrics; - the filling structure (58) comprises short fibers; - the filling structure (58) comprises monolithic areas, which were produced in particular by means of joining paste (102); - the material density of the core device (26) is higher at the at least one interface area (42) than at a certain minimum distance to the at least one interface area (42). [12] Sandwich component according to any of the preceding claims, characterized by, that the at least one interface area (42) is a connection area for the sandwich component and / or for a component on the sandwich component and in particular serves to accommodate at least one mounting element. [13] Method for producing a sandwich component comprising a first face sheet device (22), a core device (26), a second face sheet device (24) and at least one interface area (42), in particular according to one of the preceding claims, wherein a precursor (82) of the core device (26) is produced from C / C elements, a recess (108) is produced for an interface area (42) on the precursor (82) of the core device (26) or the core device (26), a precursor (110) for a tube element (44) or rod element, which is made of C / C or C / C-SiC, is positioned in the recess (108), and siliconization is carried out with an in-situ joining of the tube element (44) or the rod element with the core device (26). [14] Method according to claim 13, characterized by, that a precursor (112) for a central element (60) made of C / C or C / C-SiC is positioned on the precursor (110) for the tube element (44), in particular using joining paste (102). [15] Method according to claim 13 or 14, characterized by , that the precursor (110) for the rod element or the tube element (44) is manufactured or provided with at least one application recess (70) and in particular a continuous application recess (70), or that the tube element (44) or rod element is provided with at least one application recess (70; 136). [16] Method according to any one of claims 13 to 15, characterized by , that the precursor (82) of the core device (26) is manufactured as a 2D lattice structure with cells, the cell density being increased as the number of cells per unit area at the recess (108). [17] Method according to any one of claims 13 to 16, characterized by, that the precursor (82) of the core device (26) is produced as a 2D lattice structure with cells, wherein cells in the area of ​​the recess (108) are provided with a filling structure (58) made of C / C or C / C-SiC, which is siliconized with the siliconization of the core device (26) and the tube element (44) or rod element. [18] Method according to any one of claims 13 to 17, characterized by , that the recess (108) is produced as a cylindrical recess. [19] Method according to any one of claims 13 to 18, characterized by , that joining paste (102) is used when positioning the precursor (110) of the tube element (44) or the rod element at the recess (108). [20] Method according to any one of claims 13 to 19, characterized by at least one of the following: - a precursor of the first deck layer device (22) is made from C / C; - a precursor of the second deck layer device (24) is made from C / C; - the first layer assembly (22) and / or the second layer assembly (24) are made of C / C-SiC; - the first cover layer device (22) and / or the second cover layer device (24) is silicified along with the core device (26) during the silicification; - a precursor of the first cover layer device (22) and / or a precursor of the second cover layer device (24) is positioned on the precursor of the core device (26) by means of joining paste (102).

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