Method for producing an at least two-layered sandwich component

Abstract

The invention relates to a method for producing an at least two-layered sandwich component (50) in the form of a tube (24) or in the form of a panel (26), wherein the sandwich component (50) is exposed to a cold side (20) and to a hot side (22), comprising at least the following method steps: producing an insulation layer (54) which is made of a gas-tight, high-temperature-resistant glass foam material (10) and faces the hot side (22), and producing an outer layer (52) of the sandwich component (50), which outer layer comprises a fiber-reinforced composite material (12) and faces the cold side (20). The invention also relates to a sandwich component (50) of this type and to the use thereof in an aircraft.

Description

[0001] Process for producing a sandwich component with at least two layers

[0002] Technical area

[0003] The invention relates to a method for producing an at least two-layer sandwich component in the form of a tube or a panel, wherein the sandwich component is exposed to a cold side and a hot side. The sandwich component according to the invention can be used as a hot gas duct, an exhaust duct, a silencer, or a fire protection wall in an aircraft, for example in an airplane, land vehicle, watercraft, or spacecraft.

[0004] State of the art

[0005] DE 10 2016 000 915 A1 refers to a foundation structure for a building. The structure includes load-bearing insulation, with the insulation being intended as foam glass gravel as the base for a strip foundation. Except where load-bearing walls or supports are present, the strip foundation is completely surrounded by a layer of foam glass gravel. This prevents thermal bridges in the area of ​​the floor slab facing the exterior wall, thus preventing mold growth and moisture in the exterior corners of a building.

[0006] DE 11 2011 102 404 T5 relates to foam glass with low thermal expansion coefficients and related processes. Foam glass may contain natural glass, where the foam glass contains more than 5% aluminum oxide by weight and has a thermal expansion coefficient in the range between 4D x 10' 6 ppm / °C and 6 x 10' 6ppm / °C. A composition for producing the foam glass may comprise natural glass containing at least 5% alumina by weight of the composition, sodium carbonate comprising less than 10% by weight of the composition, and boric acid comprising at least 5% by weight of the composition. A process for producing foam glass may comprise mixing natural glass with boron to form a mixture, milling and melting the mixture at a temperature of at least 900°C, and allowing the molten mixture to cool such that the foam glass contains at least 5% alumina by weight of the foam glass and at least 5% boric oxide by weight of the foam glass.

[0007] AT 521 214 B1 relates to the shaping of glass foam into semi-finished products with fiber composites. A fiber composite semi-finished product is proposed, comprising a lower and an upper cover layer with fibers, wherein the lower cover layer is arranged parallel to the upper cover layer. Between the lower and the upper cover layer, ellipsoidal glass foam elements are arranged in at least two parallel planes, wherein in each plane the glass foam elements are arranged in a Cartesian grid and the grid points of two adjacent parallel planes are offset from one another in the direction of the planes such that the Cartesian grid points are arranged in one of the two adjacent planes, between the Cartesian grid points in the other of the two adjacent planes, wherein fibers and binding material are arranged between the ellipsoidal glass foam elements.The ellipsoidal elements are manufactured separately as finished glass foam elements and bonded to cover layers using a different material. The glass foam elements have ribs on their surfaces, with the ribs of the glass foam elements interlocking with ribs of glass foam elements arranged in adjacent layers.

[0008] DE 103 41 158 A1 relates to a structural element containing glass foam for sound dampening and sound insulation. The component containing glass foam for sound dampening and / or sound insulation is enclosed by a protective material at least on parts of the component. The glass foam component preferably has a first side, a second side, and an edge connecting the first and second sides. The protective material is preferably enclosed at least on parts of the edge and on a region near the edge of the first and second sides of the glass foam component. Furthermore, stud walls, sound absorber baffles, and gas-conducting ducts equipped with glass foam components for sound dampening and / or sound insulation are disclosed.

[0009] Previous concepts for insulated hot gas lines are generally constructed with a gas-tight metal pipe on the hot inner surface, usually surrounded by insulating material. This insulating material is generally not airtight and usually not dimensionally stable, such as insulation wool. In plant engineering, but not in aircraft construction, pipe half-shells made of foam glass exist. These are applied to the outside of an airtight metal pipe as external insulation. The joint between the two half-shells is glued, does not need to be airtight, and does not absorb any internal pressure, as this is borne solely by the inner pipe.

[0010] In aircraft construction, such inner tubes for hot gas are currently often made of titanium to meet weight, temperature, and corrosion requirements, and are therefore relatively expensive. Alternatively, such tubes are made of steel alloys, which, however, entails significant weight disadvantages in aircraft construction.

[0011] One alternative to reduce costs and weight is to manufacture such hot gas lines from fiber composites, but the high temperatures and the creation of an airtight shell present challenges. Sandwich constructions are also known, in which a foam material is framed by cover layers made of metal or fiber composite.

[0012] Description of the invention

[0013] The invention is based on the object, particularly in aviation applications, to provide a cable or plate arrangement which is very favorable in terms of weight and realizes an air-impermeable insulation layer, while at the same time ensuring resistance to high temperatures.

[0014] According to the invention, a method is proposed for producing a sandwich component having at least two layers, which is manufactured in the form of a tube or in the form of a plate, wherein the sandwich component is exposed to a cold side and a hot side, and wherein at least the following method steps are carried out: a) production of an insulation layer facing the hot side, which contains a gas-tight, high-temperature-resistant glass foam material and b) production of an outer layer of the sandwich component facing the cold side, which outer layer comprises a fiber composite material.

[0015] The method proposed according to the invention makes it possible to produce sandwich components that can withstand high and extremely high temperatures, while at the same time, by using a fiber composite material, inexpensive materials can be used that also have an extremely low weight, which is very advantageous for aviation applications.

[0016] In an advantageous embodiment of the method proposed by the invention, the insulation layer facing the hot side can be provided with a layer containing a fiber composite material with a ceramic, glass-ceramic, or glass matrix material. This optional additional layer on the insulation layer facing the hot side allows for a further increase in temperature resistance and improved mechanical resistance of the surface on the hot gas side.

[0017] Advantageously, the insulation layer facing the hot side according to process step a), which consists of a gas-tight, high-temperature-resistant glass foam material, is manufactured from a block material or with the aid of a preform which comprises at least one glass granulate and a foaming agent.

[0018] In the process proposed according to the invention, the insulation layer facing the hot side is smoothed by locally generating high temperatures. This allows, for example, broken glass pores to be smoothed by locally acting high temperatures, resulting in an extremely smooth, aerodynamically favorable interior of the insulation layer. The resulting closure of the glass foam surface also prevents water from penetrating the pores and thus preventing damage due to frost. In a further advantageous embodiment of the process proposed according to the invention, the sandwich construction element is held in a closed mold during the implementation of process steps a) and b), in which the glass granules are melted and subsequently foamed under the action of the foaming agent.

[0019] In a further advantageous embodiment of the method proposed according to the invention, the fiber material from which the cover layer or layers are formed is impregnated with the melt of the glass granulate in the closed mold as a preform in the form of a fiber molding or a porous fiber-ceramic material.

[0020] In a further advantageous embodiment of the method proposed according to the invention, the gas-tight, high-temperature-resistant glass foam material is mixed with fiber material, in particular carbon, metal, basalt or ceramic fiber material or also particularly high-temperature-resistant glass fiber material, during its production, wherein the fiber material can be present both as short fiber and as long fiber.

[0021] In a further embodiment of the method proposed by the invention, the fiber material—present as short or long fibers or as continuous fibers—is introduced into or around the glass granules prior to their melting or foaming, or as a wound preform for subsequent cover layers or as a semi-finished textile product, in particular as a braided / woven cover layer on one or more surfaces, or as a spacer fabric, which are impregnated with the glass granules during the melting and foaming process. In a further embodiment, a glass material that achieves a particularly low viscosity at the process temperature, for example, a glass solder, is used to impregnate the fiber interstices with the glass matrix.In particular, this glass material with particularly low viscosity is only used in the areas of the particularly densely packed fiber cover layers (hot and / or cold side) and in the area of ​​the glass foam a different glass material, which may also have a higher melting temperature.

[0022] In a further embodiment of the method according to the invention, the fibers used for depositing the cover layers (e.g. rovings) are already pre-impregnated with a glass material or a glass solder during the production of the wound preform, for example, in the form of a prepreg tape, which was impregnated in a previous process.

[0023] In an advantageous embodiment of the method proposed according to the invention, air channels are introduced into an outer side of the insulation layer containing the gas-tight, high-temperature-resistant glass foam material. These air channels remain permeable to air after the outer layer has been laminated on. In the event of a leak in the insulation layer, they guide air escaping through it to discrete air outlet openings assigned to the temperature sensors. Preparatory measures for a leak detection system can be taken during the manufacture of the sandwich component.

[0024] In a further advantageous embodiment of the method proposed by the invention, fiber optic temperature sensors are laminated into the outer layer of fiber material covering the insulation layer. This also allows for the provision of a subsequent leak detection device in an alternative approach.

[0025] In a further advantageous embodiment of the method proposed according to the invention, during the heat treatment of the insulation layer facing the hot side, webs of broken glass bubbles of the glass granulate are melted, which contract into a smooth surface due to surface tension, so that the inside of the insulation layer facing, for example, the hot air flow can be effectively smoothed and a low-friction flow is established.

[0026] In the method proposed according to the invention, the heat treatment is also carried out on the end faces of the sandwich component, in the event that the latter is manufactured as a tube, in order to obtain smooth surfaces for sealing a joint between two sandwich components proposed according to the invention, designed as tubes, which are to be joined together.

[0027] Advantageously, the fiber composite material with a ceramic matrix is ​​laminated to the insulation layer facing the hot side, followed by a thermal treatment of the laminate and the insulation layer to cure or pyrolyze the ceramic matrix together. This allows for a single manufacturing step. Furthermore, the composite of the fiber composite material with a ceramic matrix and the insulation layer is extremely effective.

[0028] In a further embodiment of the method proposed according to the invention, a prefabricated layer of fiber material with a ceramic, glass-ceramic, or glass-like inorganic matrix can be soldered to the gas-tight, high-temperature-resistant insulation layer facing the hot side by means of a soldering process, for example using a glass solder (i.e., a glass with a lower melting temperature than that of the foam glass). If necessary, this soldering process can also be applied to both sides, i.e., the hot side and the cold side, for example, if both can take place simultaneously in a temperature treatment process.

[0029] In a further embodiment of the method proposed according to the invention, a prefabricated layer of the fiber composite material with a ceramic matrix can be bonded to the gas-tight, high-temperature-resistant insulation layer facing the hot side by means of an adhesive process using a high-temperature-resistant adhesive. This procedure eliminates the need for high-temperature treatment between the fiber composite material with a ceramic matrix and the insulation layer.

[0030] In an advantageous embodiment of the method proposed according to the invention, the fiber composite material is applied on the cold side as an outer layer by means of thermoset prepreg-based methods, resin infusion methods, RTM methods or thermoplastic prepreg-based methods, in particular TP-AFP methods.

[0031] Furthermore, the invention relates to a sandwich component in the form of a tube or a plate, which is exposed to a cold side and a hot side. The sandwich component is formed of at least two layers and comprises an insulation layer facing the hot side, which comprises a gas-tight, high-temperature-resistant glass foam material, and an outer layer facing the cold side, which contains a fiber composite material. The sandwich component proposed according to the invention is, on the one hand, very lightweight, which is extremely advantageous for aviation applications, and, on the other hand, is characterized by the presence of an air-impermeable insulating layer, namely the insulation layer made of the glass foam material, which simultaneously withstands high temperatures.

[0032] The sandwich construction element can be designed either in the form of a tube or in the form of a plate, for example as a panel.

[0033] A further advantageous embodiment of the sandwich component proposed according to the invention provides that the insulation layer facing the hot side, which comprises a gas-tight, high-temperature-resistant glass foam material, is provided with a layer containing a fiber composite material with a ceramic, glass-ceramic, or glass matrix material. This makes it possible to provide a three-layer sandwich component that goes beyond a two-layer sandwich component and is further improved in terms of its temperature resistance, mechanical strength, and sealing requirements.

[0034] Furthermore, the invention relates to the use of the sandwich component in an aircraft, in particular in an airplane, as a hot gas line, bleed air or exhaust line, or as an engine or APU silencer. A further use of the sandwich component proposed according to the invention is its use as an enclosure for units that either become hot during operation and / or can potentially become hot in the event of a fault / failure or fire, in particular a solid oxide fuel cell or batteries or low-temperature energy converters or other waste heat-producing components of an aircraft, in particular an airplane. Furthermore, the sandwich component can be used as a fire protection barrier or the like in a land-based, water-based, or even spacecraft.

[0035] Advantages of the invention

[0036] The sandwich construction element proposed according to the invention, in particular manufactured according to the method proposed according to the invention, comprises a shell made of high-strength fiber composite material and an insulating layer made of a gas-tight, high-temperature-resistant glass foam material. The invention represents a functionality for a sandwich construction element in that it comprises, on the one hand, an air-tight insulating layer that, on the other hand, simultaneously withstands high temperatures. Previously, it was necessary, for example in bleed-air pipes in aircraft, to ensure airtightness through other layers or components because the available, high-temperature-resistant insulation materials are insufficiently airtight.

[0037] The solution proposed by the invention also enables the use of foams for high temperatures, but now with glass instead of polymer materials as the foam material. At the same time, the solution proposed by the invention enables constructions with high thermal insulation properties that, in contrast to the frequently used soft mineral or glass wool mats, exhibit increased dimensional stability and can therefore be more easily connected to structural components.

[0038] The solution proposed by the invention also allows for the roughness of mechanically machined surfaces of the glass foam material to be improved, as the number of open pores in the glass foam material on the surface, particularly on the inside of the insulation layer, is significantly reduced, thus improving the durability of this surface. Furthermore, smoothing the inside of the insulation layer reduces the flow resistance for media and simultaneously reduces the likelihood of surface particles from the insulation layer becoming detached.

[0039] The solution proposed according to the invention makes it possible to provide a sandwich component which, in particular, represents a hot gas line, for example a bleed air or exhaust line or an engine or APU silencer in an aircraft, in particular in an airplane. The proposed sandwich component comprises an outer shell made of a fiber composite material and an inner insulation layer made of a gas-tight, high-temperature-resistant glass foam material, such as foam glass. Optionally, the inner side of the insulation layer can be covered with another high-temperature-resistant material, in particular a fiber composite material with a ceramic, glass-ceramic, or glass-like, inorganic matrix. The sandwich component proposed according to the invention can be in the form of a tube or, when unfolded, as a flat panel, which serves, for example, as a heat or fire protection wall.

[0040] The solution proposed by the invention allows the previously required additional outer casing for leak detection in bleed air lines to be either reduced to a thin foil casing without additional insulation or eliminated entirely by incorporating air channels into the outer layer of the insulation layer. These channels lead to discrete, defined air outlet points in the tubular sandwich element, where temperature sensors are located. These temperature sensors can alternatively be laminated into the sandwich element in the form of foils, fibers, or wires.

[0041] Thanks to the solution proposed according to the invention, for example in the case of a sandwich component according to the invention in the form of a tube, the outer layer made of fiber composite material can absorb the tensile load that can arise, for example, from internal pressure in the tube, and not the inner tube as in previous applications. The gas-tight, high-temperature-resistant foam glass material, on the other hand, in addition to its insulating function, also takes on the task of ensuring the tightness of the tubular sandwich component, so that the outer layer made of fiber composite material does not have to take on this task. This advantageously makes it possible to use materials for the outer shell, i.e. the outer layer, which have a lower temperature resistance than would be the case for an inner shell in contact with the hot gas.Since a much wider selection of fiber composite materials is available, materials with better mechanical properties and / or lower price or processing costs can also be used. The foam glass material used as an insulation layer, on the other hand, has the advantage of hardly outgassing, thus preventing vapors from contaminating the hot medium.

[0042] To increase the strength of the insulation layer, fiber material in the form of carbon, metal (e.g., steel or nickel-based superalloy), basalt, ceramic fibers, or even particularly high-temperature-resistant glass fibers can be incorporated during the production of the glass granules and / or the glass foam material in order to increase the strength and damage tolerance of this material. The fiber material, available as short, long, or so-called continuous fibers, serves as stiffener and crack stopper in the glass foam material. The fiber material can be mixed into the glass granules before they are melted or foamed, or can be incorporated as a wound preform (for subsequent cover layers) or textile semi-finished product, particularly as a braided or woven cover layer or spacer fabric. These fiber materials can then be bonded to and impregnated by the glass granules during the melting and foaming process.To facilitate the impregnation of the fiber interstices with the glass matrix, a glass material that achieves a particularly low viscosity at the process temperature, such as a glass solder, can be used if necessary. Furthermore, this particularly low-viscosity glass material can also be used only in the areas of the fiber cover layers (hot and / or cold sides), while a different glass material, which may also have a higher melting temperature, can be used in the glass foam area.

[0043] In the event of external impact stress on the sandwich component according to the invention, in particular on the outer layer made of fiber composite material, this layer must be designed with regard to its residual mechanical strength. However, the risk of leaks occurring even under minor stress on the tubular sandwich component according to the invention is low, since the insulation layer made of foam material is located underneath. Since this layer comprises many individual cells, each of which is individually gas-tight, gas-tightness can still be expected even if some of the outer cells are damaged. This provides an additional safety advantage, since small impact stresses are often below the visible range and therefore go undetected, while the construction is tolerant of these small damages.

[0044] By incorporating air ducts on the outside of the insulation layer, preparatory work can be done for a leak detection device. If it is ensured during subsequent manufacturing steps that the air ducts remain permeable to air even after the outer layer made of fiber composite material has been laminated on, they direct air escaping from the inner layer, i.e. the insulation layer, to discrete air outlet points in the outer layer, in front of which temperature sensors are placed. This can eliminate the need for an additional, non-structural air duct casing. Alternatively, a leak detection device can be created by laminating fiber optic sensors into the outer layer made of fiber composite material. If a leak in the insulation layer and the resulting escaping air cause a local temperature increase in the outer layer, the leak can be detected.

[0045] Another possible leak detection device is to enclose the rigid, load-bearing outer layer with a simple air-conducting sleeve made of foil material, which, in the event of a fault, directs escaping air to specific openings with temperature sensors. Since this foil outer shell no longer serves an insulating function, it is significantly easier to manufacture and install. A foil reserve in the form of folds or embossing can ensure that, in the event of escaping air, there is sufficient space between the outer shell and the foil, or that it is created by the differential pressure, so that this air can flow to discrete openings in the foil with leak detection sensors.

[0046] The inside of the insulation layer is advantageously designed as a smooth surface, which can be achieved through heat treatment, whereby webs of broken glass bubbles melt and the surface of the molten glass contracts into a smooth surface. This locally reduces the volume of the glass foam material, so that a blank, possibly machined, must be produced with a corresponding oversize on the sides to be treated. Furthermore, the surface heat treatment must be dosed such that the desired geometry is achieved after treatment and melting. The desired layer thickness of the glass foam material, which is then no longer porous on the surface but monolithic, can be influenced by this and by the size of the excess.The heat treatment can be carried out, for example, using a laser or with a device based on gas combustion or arc, similar to welding or glassblowing. The heat treatment can advantageously be carried out on the end faces of pipe ends in order to achieve a smooth surface for sealing the joint. In order to create a surface on the end faces of the pipe ends that is not only smooth but also flat or geometrically precisely tailored to a seal, the use of a hot stamping tool or similar can also be used to carry out the heat treatment. To avoid harmful tensile stresses in the workpiece, it can also be useful to either heat the entire blank to a higher temperature level during its surface treatment and / or to carry out a heat treatment following the surface treatment, similar to glass tempering processes.

[0047] The sandwich construction element proposed by the invention can be used to enclose hot components, such as an aircraft's APU (Auxiliary Power Unit), for air intake or exhaust ducting, or for enclosing associated silencers, which also become hot. Airtightness is negligible here, so the sandwich construction elements proposed by the invention can also be manufactured in sections. Unlike insulating wool, these have a solid structure, and consequently, there is a solid connecting layer on both sides, which offers advantages for fastening elements internally or for connecting them to the structure externally. For example, fewer structural elements need to be passed through the insulation layer, reducing thermal bridges.

[0048] A sandwich component proposed according to the invention with fiber ceramic on one side, an insulating layer of glass foam material in the middle, and fiber composite material as the outer layer can be used to enclose other hot components, such as a solid oxide fuel cell, or to provide safety-enhancing enclosures for potentially hot components, such as batteries, low-temperature fuel cells, and other energy converters. The sandwich components proposed according to the invention can also be used as structural elements, for example, as external heat shields, such as in spacecraft for atmospheric re-entry or in supersonic aircraft. In this case, the fiber ceramic cover layer is on the outside, and the outer layer made of fiber composite material is on the inside of the missile.

[0049] Short description of the drawings

[0050] The invention is described in more detail below with reference to the drawings.

[0051] Figure 1 shows a sandwich construction element according to the invention, designed as a tube with an insulation layer made of glass foam material and an outer layer made of fiber composite material,

[0052] Figure 2 shows an embodiment of the sandwich component according to the invention with an additional layer of a fiber composite material with a ceramic or glass-like, inorganic matrix on the inside of the insulation layer,

[0053] Figure 3 shows a schematically indicated device for locally increasing the temperature to smooth the inside of the insulation layer,

[0054] Figure 4 shows a sandwich construction element designed as a plate or panel, proposed according to the invention,

[0055] Figure 5 shows a cross-section through a tubular sandwich component according to the invention with attachments or built-ins on the cold side and hot side,

[0056] Figures 6a - 6d show a manufacturing process of a tubular sandwich component,

[0057] Figure 7 shows a sandwich component designed as a tube,

[0058] Figure 8 shows a sandwich component, also designed as a tube, enclosed by an air guiding shell and

[0059] Figures 9 and 9.1 show a sandwich component, also designed as a tube, with fiber optic sensors laminated into the outer layer.

[0060] Implementation variants of the invention

[0061] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention. Figure 1 shows a sandwich component 50 designed as a tube 24, proposed according to the invention.

[0062] From the illustration in Figure 1, it can be seen that the sandwich component 50 proposed according to the invention is designed in the form of a tube 24. According to the illustration in Figure 1, the sandwich component 50 is exposed to a cold side 20 and a hot side 22. The cold side 20 can, for example, be the environment where ambient temperature prevails, while on the hot side 22, the flow cross-section of the tube 24 is subjected to, for example, hot air or another hot gas. Consequently, higher temperatures prevail in the flow cross-section of the tube 24 than on its exterior, the cold side 20.

[0063] The sandwich component 50 in the form of the tube 24 contains a surrounding insulation layer 54 comprising a gas-tight, high-temperature-resistant glass foam material 10. Furthermore, the sandwich component 50 configured as a tube 24 according to Figure 1 comprises an outer layer 52 made of fiber composite material. In the embodiment according to Figure 1, a glass layer 14 is formed on the inner side of the insulation layer 54 facing the hot side 22. This glass layer forms the surface of the gas-tight, high-temperature-resistant glass foam material 10, which defines the flow cross-section of the tube 24, i.e., its cavity.

[0064] Figure 2 shows an alternative embodiment of the sandwich component 50 proposed according to the invention, which, according to Figure 2, is also designed as a tube 24. The sandwich component 50 comprises an outer layer 52 comprising a fiber composite material 12. The outer layer 52 encloses said insulation layer 54, which comprises a gas-tight, high-temperature-resistant glass foam material 10. A further layer in the form of a fiber composite material 16 with, for example, a ceramic matrix or with a glass-like, inorganic matrix is ​​applied, glued, soldered, or laminated onto the glass layer 14.

[0065] While according to Figure 1 the sandwich component 50 designed as a tube 24 has a glass layer 14 as the surface of the insulation layer 54 on its inner side, which defines the flow cross-section and is exposed to the hot side 22, the illustration of the embodiment according to Figure 2 shows a sandwich component 50 which can be exposed to higher temperatures and / or mechanical loads. In the event that the expected loads on the side of the sandwich component 50 designed for high temperatures are such that they cannot be absorbed by the insulation layer 54 alone or by a glass layer present after surface treatment alone, the hot side 22 of the sandwich component 50 can be fiber-reinforced with the embodiment according to Figure 2.To obtain a sandwich construction with glass foam material 10 and fiber reinforcement on both sides, a layer of fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix is ​​applied to the hot side 22 of the insulation layer 54, i.e., to the glass layer 14. This can be achieved, for example, by direct lamination onto the insulation layer 54, which comprises a gas-tight, high-temperature-resistant glass foam material 10. Subsequently, the laminated layer and the glass foam material 10 are subjected to a temperature treatment together for consolidation or curing, or for pyrolysis of the fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix, if the temperature resistance of the foam glass material 10 is high enough for the process required for curing.Alternatively, it is possible to apply a previously separately produced layer of fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix to the glass layer 14 of the insulation layer 54 by means of an adhesive process or a glass solder process, in which case an adhesive or a glass solder that is also resistant to high temperatures can be used.

[0066] In a variation of this embodiment (not shown), the glass layer 14 is omitted, and the layer of fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix is ​​applied directly to the surface of the glass foam material 10 on the hot side 22 of the insulation layer 54.

[0067] The illustration in Figure 3 shows a heat treatment of the glass layer 14 of the glass foam material 10 facing the hot side 22, which forms the insulation layer 54. The illustration in Figure 3 shows that a device 18 is used for locally generating high temperatures for melting the surface of the glass foam material 10. The device 18 can be, for example, a laser or a device based on gas combustion or an arc, similar to welding and glass blowing work. The illustration in Figure 3 shows that the device 18 is moved in a feed direction 92 along the glass layer 14 of the glass foam material 10. In the process, the outer region of the glass foam material 10, which is exposed to the heat treatment, melts together, any remaining open glass pores close, and due to the surface tension, a shrinkage of the insulation layer 54 occurs, i.e.of the glass foam material 10 from an excess dimension 96 to a nominal dimension 98. In addition to the reduction of the thickness of the insulation layer 54 from the excess dimension 96 to the nominal dimension 98, a very smooth state is established on the glass layer 14, since the open glass pores are closed and, due to the surface tension, a very smooth inner side of the glass foam material 10 representing the insulation layer 54 is formed, which is directed towards the hot side 22 of the insulation layer 54.

[0068] The illustration in Figure 4 shows a further embodiment of the sandwich component 90 proposed according to the invention, which in this case is designed as a flat plate or panel. In the embodiment variant shown in Figure 4, the sandwich component 90 comprises the insulation layer 54, which comprises the gas-tight, high-temperature-resistant glass foam material 10. On the side facing the hot side 22, the insulation layer 54 of the sandwich component 90 is provided with the fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix, while on the cold side 20, the fiber composite material 12 is arranged as the outer layer 52, which is made of a very lightweight fiber composite material 12 that thus has favorable weight properties for aircraft construction.

[0069] According to the embodiment variant in Figure 4, the sandwich construction element 90 can also serve as a heat or fire protection wall.

[0070] Figure 5 shows a variant of the sandwich component 50 proposed according to the invention, which is designed with a variable cross-section. The sandwich component 50, shown in section in Figure 5 and also designed in the form of a tube 24, has a variable cross-section. The hot side 22 is formed, for example, by the flow cross-section of the tube 24 designed with a variable cross-section, through which, for example, a hot air stream flows. Resonator chambers 25, which serve for sound absorption, are adjacent to the tube 24 shown in dashed lines. The sandwich component 50 in the form of the tube 24 comprises the insulation layer 54, formed from the gas-tight, high-temperature-resistant glass foam material 10, furthermore the fiber composite material 12 forming the outer layer 52, and, facing the hot side 22, the fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix, i.e.In this embodiment, the sandwich component 50 is formed in three layers.

[0071] From the illustration in Figure 5, it can be seen that the sandwich component 50 in this embodiment can be connected, for example, to structural elements of an aircraft, in particular an airplane, on the cold side 20 under normal ambient conditions, for example via attachments 30, for example made of fiber composite material. Furthermore, Figure 5 shows that attachments 28 are also arranged on the hot side 22 of the sandwich component 50, i.e., in the flow cross-section of the pipe 24. These attachments 28 consist, for example, of a fiber composite material 12 with a CMC matrix and can therefore withstand high temperatures such as those that can occur on the hot side 22 of the sandwich component 50.

[0072] Figure 5 shows that the tube 24 of the sandwich component 50 has several attachments 28 made of a fiber composite material 16 with a ceramic matrix or a glass-like, inorganic matrix arranged one behind the other in the axial direction. They protrude from the inside of the fiber composite material 16 with a ceramic matrix or a glass-like, inorganic matrix into the flow cross-section. The diameter of the sandwich component 50 formed as tube 24 is indicated by dashed lines. The insulation layer 54 comprises the glass foam material 10, which is produced from glass granules 62 with the addition of a foaming agent.To improve strength, crack resistance, or mechanical strength, fiber material in short form 58 or long form 60 is mixed into the glass granulate 62. The fiber material can be carbon, metal (e.g., steel or nickel-based superalloys), basalt, or ceramic fibers, or high-temperature-resistant glass fibers. It is also possible to incorporate wound preforms (for subsequent cover layers) or semi-finished textiles in the form of braided or woven cover layers or in the form of spacer fabrics during the production of the glass foam material 10. These preforms are then penetrated by the foaming agent during the melting and foaming process of the glass granulate 62, assisted by the foaming agent. Such a production process can be seen, for example, in the sequence of figures 6a to 6d.

[0073] The illustration in Figure 6a shows that dry reinforcing fibers 32 associated with the inner tube surface are wound around an inner mold 34. The inner mold part 34 can, for example, be divisible, have a draft angle or the like, or enable demolding based on a difference in thermal expansion. In the latter case, this can be achieved, for example, by selecting a material for the inner mold part 34 that has a higher thermal expansion than the material of the workpiece solidified after the forming process, so that the inner mold part 34 contracts more than the workpiece during the cooling process.

[0074] Figure 6b shows how, according to or independently of the previously described process, dry reinforcing fibers assigned to the outer pipe surface are wound around a preform 36, which represents a hollow component. The hollow preform 36 comprises a mixture of glass granules 62 with foaming agent and a binding material. Furthermore, the granules 62 can contain short fibers 58 or long fibers 60 if they are needed as crack stoppers in the glass foam material 10 to be foamed. The fibers applied according to Figure 6b are not the same as in Figure 6a, but rather new fibers that later form an outer covering layer. The hollow preform made of glass granules, foaming agent, and binding material is required as a support for the winding process in order to hold the fibers on the circumference of the outer diameter, since a cavity is still needed in the mold to provide space for foaming the foam glass.The inner fiber layer remains wound on the inner mold until after the foaming process, when the finished component is demolded.

[0075] The preform 36 prepared according to Figure 6b is either manufactured around the preform 36 prepared according to Figure 6a, or the preforms 36 manufactured according to Figures 6a and 6b are manufactured separately and then joined together, for example, by sliding them into one another. The combination of the two preforms 36 is transferred into a closed mold 100, as described below, wherein the inner mold part 34 described in Figure 6a can represent a part of this closed mold.

[0076] Figure 6c shows that the closed mold 100 is designed to be divisible and comprises a first mold half 102 and a second mold half 104.

[0077] The inner mold 34 prepared according to Figure 6a is enclosed by the closed mold 100 or its mold halves 102 and 104, and both preforms 36 are joined together in a closed mold 100. For this purpose, a heating process to approximately 800 °C takes place, during which the glass granulate 62 melts and foams, so that the fiber layers of the dry reinforcing fibers 32 are impregnated.

[0078] In the illustration according to Figure 6c, reference numeral 40 denotes an expansion during the foaming process. The foaming space is defined by the annular region between the dry reinforcing fibers 32 on the circumference of the inner mold 34 and, on the other hand, by the inner side of the glass foam material 10 to be foamed.

[0079] After completion of the foaming process, a blank of a sandwich component 90 made of fiber-ceramic or fiber-reinforced glass, foam glass, and fiber-reinforced composite material 12 is obtained. The sandwich component 90 shown in Figure 6d thus comprises an outer layer 52 made of fiber-reinforced composite material 12, which covers the insulation layer 54 made of foamed glass foam material 10, which in turn is covered on its side facing the hot side 22 with the fiber-reinforced composite material 16 with a ceramic matrix or glass-like, inorganic matrix. The resulting blank shown in Figure 6d is cooled and demolded, exhibiting a near-net-shape foam glass sandwich structure with a fiber-reinforced outer and inner sides.

[0080] According to an alternative embodiment of the process described in Figures 6a to 6d, the reinforcing fibers 32 may also have already been fully or partially impregnated with a glass-like matrix beforehand, so that they are in the form of flat prepreg strips and can be wound in this form onto the inner mold 34 or the preform 36 in the described processes. In this case, the glass from the glass granulate has not penetrated, or not as deeply, into the fiber cover layers during the foaming process, which may have advantages for highly viscous glasses.

[0081] The sandwich construction element 50, 90 described above with reference to Figures 1 to 6d, and its manufacturing method, enables the use of the glass foam material 10 as the insulation layer 54 on the hot side 22 and the use of a fiber composite material 12 as the outer layer 52 on the cold side 20. The outer layer 52 made of fiber composite material 12 absorbs the tensile load, which can arise, for example, from internal pressure in the pipe 24, rather than the inner pipe as usual. The gas-tight, high-temperature-resistant glass foam material 10, in contrast, not only performs the insulating function but also the task of sealing the pipe 24, so that this function is not ensured by the fiber composite material 12.The described sandwich component 50, designed as a tube 24, has the advantage that materials can be used for the outer layer 52 that have a lower temperature resistance than would be the case for an inner shell in contact with a hot gas stream on the hot side 22. Since a significantly larger selection of fiber composite materials is thus available, materials with better mechanical properties and / or lower price or processing costs can also be used. The glass foam material 10, in turn, has the advantage that it hardly outgasses, thus preventing the hot medium from being contaminated with vapors.

[0082] The sandwich component 50 proposed according to the invention can be expanded to include a leak detection device 66. For this purpose, air channels 76 can be introduced into the outer side of the insulation layer 54, which contains a gas-tight, high-temperature-resistant glass foam material 10, for example, by milling or molding. These remain permeable to air even after the outer layer 52 in the form of the fiber composite material 12 has been laminated on, and in the event of a leak in the insulation layer 54, they guide any air escaping there to the discrete air outlet points 68 located in a fiber composite shell 78. Temperature sensors 72 are located in front of these air outlet points. Thus, the sandwich component 50 additionally assumes the function of a non-structural air guide shell that would otherwise be located further out, which can be omitted in this case.The discrete air outlet points 68 are dimensioned such that the outer shell's ability to absorb the circumferential forces caused by the internal pressure is still ensured. The cell walls of the foam glass and any fibers embedded therein are dimensioned such that the cells do not collapse despite the local pressure difference.

[0083] Another possibility for integrating a leak detection device 66 is to laminate fiber optic sensors 82 into the outer structural fiber composite shell 78. Since, in the event of a leak in the insulation layer 54, the resulting escaping hot air causes a local temperature increase in the outer layer 52, the leak can be detected in this way, provided that the distance between the fiber optic sensors 82 is small enough so that the temperature influence area of ​​a critical leak is not smaller than the grid of the arrangement of the temperature sensors 72.

[0084] Another possibility for integrating the leak detection device 66 is to wrap the rigid, load-bearing outer layer 52 with a simple air-conducting sleeve made of film 84, which directs potentially escaping hot air to specific openings with temperature sensors 72. Since this outer sleeve no longer performs an insulating function, it is significantly simpler to manufacture and easier to install. A film reserve 88 in the form of folds or embossing can ensure that, in the event of escaping air, there is sufficient space between the outer sleeve and the film, or is formed by the differential pressure, so that this air can flow to discrete openings in the film with leak detection sensors 66.

[0085] If the insulation layer 54 is manufactured from a block material by mechanical processing, the surface of the insulation layer 54 facing the hot side 22 is very rough. The surface of the glass foam layer 54 (insulation layer) consists of a number of webs of broken glass bubble cells. On the outside, where the outer layer 52 is laminated, this is advantageous for the adhesion of the fiber composite material 12. However, a smooth surface on the inside of the insulation layer 54 is advantageous. It is also advantageous if there are no open glass pores 94 there, into which liquid could potentially penetrate. To achieve this, the surface of the insulation layer 54 facing the hot side 22 is heat-treated.In this process, webs of broken glass pores 94 of the glass foam material 10 are melted, which contract due to the surface tension of the molten glass foam material 10 to form a smoother surface. Since the volume of the glass foam material 10 decreases locally, the machined blank must be produced with a corresponding oversize 96 on the sides to be treated, and the surface-active heat treatment must be dosed such that the desired nominal dimension 98 is achieved after the heat treatment and contraction. The desired layer thickness of the glass foam material 10, which is then no longer porous but monolithic on the surface, can also be influenced by the size of the excess 96 provided.

[0086] The surface treatment can be carried out, for example, using the device 18 in the form of a laser or with a device based on gas combustion or arc.

[0087] In particular, the described heat treatment can also be performed on the end faces of the pipe ends of the sandwich components 50 manufactured as pipes 24 in order to achieve a smooth surface for sealing the joints between two pipes 24 to be connected. In order to create not only a smooth surface, but also a flat surface or one that precisely matches the geometry of a seal, the use of a hot stamping tool or the like can also be considered.

[0088] In order to prevent surface tensile stresses or other harmful tensile stresses in the insulation layer 54, which comprises a gas-tight, high-temperature-resistant glass foam material 10, it may be useful either to heat the blank as a whole to an elevated temperature level during the surface treatment and / or to carry out a heat treatment following the surface treatment, similar to glass tempering processes.

[0089] For particularly temperature-intensive applications and in the event that the expected loads on the hot side 22 of a sandwich component 50 are such that they cannot be absorbed by the insulation layer 54 or a glass layer 14 smoothed after surface treatment alone, fiber reinforcement can be applied to the hot side 22. For this purpose, a fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix is ​​applied to the untreated surface of the insulation layer 54 on the side of the insulation layer 54 facing the hot side 22.Its application can be carried out, for example, by direct lamination and subsequent temperature treatment of the laminated layer and the insulation layer 54 together for consolidation and curing or pyrolysis of the fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix, if the temperature resistance of the glass foam material 10 is high enough for the process necessary for the above-mentioned fiber composite material 16 (e.g. glass soldering process).

[0090] The sandwich construction element proposed according to the invention can be used in hot gas lines, for air or exhaust gas routing, or as a housing for hot units, such as an APU (Auxiliary Power Unit) of an aircraft. Furthermore, it can be used as a housing for associated silencers. In housing applications, airtightness plays a lesser role, so that the sandwich construction elements 50 can also be manufactured in sections in this case. However, one advantage is that the sandwich construction element 50, unlike insulating wool, has a solid structure and therefore has a solid connecting layer on both sides, which is suitable for attaching add-on elements (cf. positions 28, 30) or for connecting to external structures.

[0091] In a similar way, the sandwich component 50 proposed according to the invention with a fiber composite material 16 with a ceramic matrix or with a glass-like, inorganic matrix of an insulation layer 54, which has a gas-tight, high-temperature-resistant glass foam material 10 and a fiber composite material 12 as outer layer 52, can be used to enclose other hot units, such as a solid oxide fuel cell, or to enclose potentially hot units (e.g. in the event of a fault), such as batteries, low-temperature fuel cells, or other energy converters, in order to increase safety.

[0092] A further application for the described sandwich component 50, 90 proposed according to the invention can be structural elements that serve as external heat shields, for example in spacecraft, where they provide heat protection during atmospheric re-entry, or in supersonic aircraft. In this case, the side provided with the fiber composite material 16 with a ceramic matrix or glass-like, inorganic matrix is ​​located on the outside, and the outer layer 52 made of the fiber composite material 12 is arranged on the inside of the aircraft. In this application, too, an adaptation of the principle described above of laminating fiber optic sensors 82, in this case optionally also into the fiber ceramic cover layer or into the inner fiber composite layer, or into both, can serve to detect leaks or damage.

[0093] The outer layer 52 on the cold side 20, which is made of duroplastic or thermoplastic fiber composite material 12, can only be applied or laminated on if no processes with extremely high temperatures are carried out afterwards, as are necessary for the processing of glass or ceramic material, but only processes with temperatures in the normal processing range of the plastic fiber composite.For the application of the fiber composite material 12 serving as the outer layer 52, almost all common processes can be used, such as thermoset prepreg-based processes, resin infusion processes, RTM processes (Resin Transfer Molding), thermoplastic prepreg-based processes, such as TP-AFP processes (Thermoplastic Automated Fiber Placement), as long as the mechanical and thermal loads, for example due to autoclave pressure, laying head contact pressure or temperature gradients, are not higher than the load limit of the glass foam material 10 used as the insulation layer 54.

[0094] Figures 7 and 7.1 show the sandwich component 50, designed as a tube 24. The hot side is designated by reference numeral 22, while the cold side is identified by reference numeral 20. A leakage point 48 extends from the hot side 22, through which hot medium flows from the hot side 22 towards the cold side 20 through the glass foam material 10, which forms the insulation layer 54, via air ducts 76 towards an outlet 68 in the region of the outer layer 22. Opposite the outlet 68 on the outer layer 52 is a temperature sensor 72. This sensor detects the temperature increase caused by the escaping hot medium. Figure 7.1 shows air ducts 76 that cross one another and are embedded in the outer layer 52 of the sandwich component 50, which is also designed as a tube 24.The pipe 24 has end faces 86 at which the pipe 24 can be integrated into a line or connected to other pipes at corresponding joints. Figure 8 shows that the sandwich component 50, which here is also designed as a pipe 24, is enclosed by an air guiding sleeve 84, for example made of a film material. As can be seen from Figure 8, the air guiding sleeve 84 has film reserves 88 at, for example, opposite points, so that if medium escapes through a leak in the foam glass layer and the fiber composite layers, this is caught by the air guiding sleeve 84 and, thanks to the existing reserve 88, a space can form between the outer fiber composite layer and the air guiding sleeve 84, so that the air flows through this space to one of the outlets 68 and only then escapes to the outside.In Figure 8, the sandwich component 50, designed as a tube 24, is also shown to have a medium flowing through it on the hot side 22. Analogous to the illustration in Figure 7, a temperature sensor 72 is also assigned to the outlet 68. The sandwich component 50 comprises, in addition to the glass foam material 10 and the fiber composite material 12 as the outer layer 52, the fiber composite material 16 with a ceramic matrix or with a glassy, ​​inorganic matrix on its inner side.

[0095] Figures 9 and 9.1 show that the sandwich component 50, here also designed as a tube 24, can comprise fiber optic sensors 82 laminated into its outer layer 52. These are arranged on the outside of the tube 24, i.e. on the outer layer 52, analogously to the course of air ducts 76 (cf. illustration according to Figure 7.1). The sandwich component 50 shown in Figure 9 in the form of the tube 24 is one which is constructed analogously to the sandwich component 50 according to Figure 7, namely it contains the glass foam material 10 as the insulation layer 54 and the fiber composite material 12 as the outer layer 52. The fiber optic sensors 82 are laminated into the outer layer 52.

[0096] The arrangement of the fiber optic sensors 82 can correspond to the arrangement of the air ducts 76, although this is not absolutely necessary. For the air ducts 76, for example, it is expedient for them to cross over regularly; for fiber optic sensors 82, a close-meshed, spiral winding in only one direction, without any crossovers, is also possible. The air ducts 76 according to Figure 7 are located in the foam glass layer, while the fiber optic sensors 82 according to Figure 9 can be assigned to the outer fiber composite layer. The invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, a multitude of modifications are possible within the scope specified by the claims, which are within the scope of one skilled in the art.

[0097] List of reference symbols

[0098] 10 Glass foam material

[0099] 12 Fiber composite material

[0100] 14 Glass layer on the surface of the glass foam material

[0101] 16 Fiber composite material with ceramic or glass-like, inorganic

[0102] matrix

[0103] 18 Device for the local generation of high temperatures

[0104] 20 Cold side

[0105] 22 Hot side

[0106] 24 pipe

[0107] 25 resonator chambers

[0108] 26 Plate, panel

[0109] 28 Attachments structure or system on hot side

[0110] 30 attachments made of fiber composite material on the cold side

[0111] 32 dry reinforcing fibers

[0112] 34 Inner form

[0113] 36 Preform

[0114] 38 Outer shape

[0115] 40 Expansion during the foaming process

[0116] 48 Leakage point

[0117] 50 sandwich construction elements

[0118] 52 Outer layer or layer on cold side

[0119] 54 Insulation layer

[0120] 56 fiber materials (metal, basalt, glass, carbon and ceramic fibers)

[0121] 58 short fibers

[0122] 60 long fibers

[0123] 62 glass granules

[0124] 64 textile semi-finished products

[0125] 66 Leak detection device

[0126] 68 Outlet

[0127] 70

[0128] 72 Temperature sensor

[0129] 74

[0130] 76 air ducts in the outer insulation layer

[0131] 78 Fiber composite sheath Laminated fiber optic sensors

[0132] Air duct cover made of foil

[0133] front side

[0134] Foil reserve

[0135] Sandwich element made of fiber composite material with inorganic

[0136] Matrix, foam glass and general composite material

[0137] Feed direction

[0138] Open glass pores

[0139] Excess

[0140] nominal size

[0141] Closed form

[0142] First mold half

[0143] Second mold half

Claims

Patent claims 1. Method for producing a sandwich element (50) of at least two layers in the form of a tube (24) or in the form of a plate (26), wherein the sandwich element (50) is exposed to a cold side (20) and a hot side (22), comprising at least the following process steps: a) producing an insulating layer (54) facing the hot side (22) from a gas-tight, high-temperature-resistant glass foam material (10) and b) producing an outer layer (52) of the sandwich element (50) facing the cold side (20), comprising a fiber composite material (12).

2. Method according to claim 1, characterized in that the insulating layer (54) facing the hot side (22) is provided with a layer containing a fiber composite material (16) with a ceramic, glass ceramic or glass matrix material.

3. Method according to claims 1 or 2, characterized in that the insulating layer (54) facing the hot gas side (22) according to process step a), which comprises a gas-tight, high-temperature-resistant glass foam material (10), is made from a foam block material or from a preform (36), the latter comprising at least a glass granulate (62) and a foaming agent.

4. Method according to claims 1 to 3, characterized in that the insulating layer (54) facing the hot side (22) is smoothed by locally generating high temperatures, such that an open-pore-free glass layer (14) is obtained after smoothing.

5. Method according to one of claims 1 to 4, characterized in that the sandwich component (50) is held in a closed form (100) during the execution of at least the method step a) in which the glass granules (62) are melted and foamed. A method according to claim 5, characterized in that, in the closed form (100), a fiber-containing layer (32) made from a fiber preform (36) or a temperature-resistant, porous fiber composite material (12) is completely or partially impregnated with the melt of the glass granules (62). A method according to claims 1 to 6, characterized in that the gas-tight, high-temperature-resistant foam material (10) is provided with fiber material, in particular carbon, metal (for example, steel or nickel-based superalloy), basalt, ceramic fibers, or temperature-resistant glass fibers, during its production, wherein the fiber material is present as short fibers (58), long fibers (60), or continuous fibers.Method according to claim 7, characterized in that the fiber material is introduced into the glass granules (62) as short fibers (58) or as long fibers (60) before its melting or foaming, or is introduced as a wound preform (36) for cover layers or as a textile semi-finished product, in particular as a braid or woven cover layer or spacer fabric, which are impregnated by the glass granules (62) during the melting and foaming process.A method according to claims 1 to 8, characterized in that a preform (36) is produced from a mixture comprising glass granules (62), foaming agent, and binder, such that the preform (36) serves as a support for the application of further preforms (36) for one of the fiber cover layers, and thus the position of the cavity into which the foam material expands during expansion and where the material to be cured and the fibers are located can be controlled by means of the preform(s) (36). A method according to claims 1 to 9, characterized in that air channels (76) are embedded on an outer surface of the insulation layer (54), which contains a gas-tight, high-temperature-resistant glass foam material (10), which remain permeable to air after lamination of the outer layer (52) and, in the event of a leak in the insulation layer (54), direct escaping air to discrete outlets (68) to which temperature sensors (72) are assigned.

11. Method according to claims 1 to 9, characterized in that fiber optic temperature sensors (82) are laminated into the outer layer (52) of the fiber composite material (12) covering the insulating layer (54).

12. Method according to claim 4, characterized in that during the heat treatment of the insulating layer (54) facing the hot side (22), webs of broken glass bubbles (94) melt and contract to form a smooth surface due to surface tension, or a predetermined surface geometry is produced by pressing a hot forming tool.

13. Method according to claim 4 or 11, characterized in that the heat treatment is carried out on end faces (86) of the sandwich component (50) as a tube (24) in order to obtain smooth surfaces for sealing a joint between two tubes (24).

14. Method according to claim 2, characterized in that the fiber composite material (16) with ceramic matrix or glassy, ​​inorganic matrix is ​​laminated onto the insulating layer (54) facing the hot side (22) and a heat treatment of the laminate and the insulating layer (54) is carried out together for the consolidation / curing / pyrolysis of this fiber composite material (16).

15. Method according to claim 2, characterized in that a prefabricated layer of the fiber composite material (16) with ceramic matrix or with glassy, ​​inorganic matrix is ​​applied to the gas-tight, high-temperature-resistant insulating layer (54) facing the hot side (22) by means of an adhesive process with a high-temperature-resistant adhesive or by means of a glass soldering process with a glass solder.

16. Method according to claims 1 to 15, characterized in that the fiber composite material (12) is applied on the cold side (20) as an outer layer (52) by means of thermoset prepreg-based processes or resin infusion processes, RTM processes (resin transfer molding injection molding) or thermoplastic Prepreg-based processes, in particular TP-AFP (Thermoplastic Automated Fiber Placement) processes, are applied. Sandwich component (50) in the form of a tube (24) or in the form of a plate (26), which is exposed to a cold side (20) and a hot side (22), manufactured according to one of claims 1 to 16, characterized in that the sandwich component (50) is formed in at least two layers and comprises an insulating layer (54) facing the hot side (22), which comprises a gas-tight, high-temperature-resistant glass foam material (10), and an outer layer (52) facing the cold side (20) made of a fiber composite material (12).Sandwich component (50) according to claim 17, characterized in that the insulating layer (54) facing the hot side (22), which comprises a gas-tight, high-temperature-resistant glass foam material (10), is provided with a layer containing a fiber composite material (16) with a ceramic matrix or with a glass-like, inorganic matrix. Use of the sandwich component (50) according to claims 17 or 18 in an aircraft as a hot gas duct, bleed air duct, exhaust duct, engine silencer, or APU silencer (APU = Auxiliary Power Unit). Use of the sandwich component (50) according to claims 17 or 18 for housing potentially hot components during normal operation and / or in the event of a fault or fire in an aircraft, in particular a solid oxide fuel cell or at least one battery or low-temperature energy converter.

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