Insulating film for pressure sensor, pressure sensor having insulating film, and production thereof

Abstract

The invention relates to a heat-insulating film (2) for a pressure sensor (1) for determining the pressure of a fluid medium (F), comprising a film body (3) and a coating (5), a film surface (6) of the film body (3) facing the fluid medium (F) when the heat-insulating film (2) is used. The coating (5) has a layer-like structure (7), the longitudinal extension (DL) of which perpendicular to the film plane (XY) is at most half of the transverse extension (DQ) of which parallel to the film plane (XY) for a plurality of layers (9).

Description

Technical Field

[0001] This invention relates to a heat-insulating film for a pressure sensor, a pressure sensor having a heat-insulating film, and the manufacture of a pressure sensor having a heat-insulating film. The heat-insulating film has a film body and a coating. Background Technology

[0002] A membrane separates the fluid medium in the first space from the second space. In the field of pressure measurement technology, pressure sensors typically have a membrane that separates the measuring device (e.g., a measuring unit) from the fluid medium (e.g., a gaseous and / or liquid measuring medium whose pressure needs to be determined). Here, the membrane typically has a membrane surface facing the fluid medium.

[0003] For pressure sensors, the pressure exerted by the fluid medium on the membrane region should be transmitted to the measuring device as losslessly as possible. Here, the measuring device can be directly positioned on the side of the membrane facing away from the fluid medium, or it can be effectively connected to the membrane via other elements (such as a fixed piston, fluid medium, or gel) that transmit the pressure or proportional force to the measuring device.

[0004] When sensors are used in environments with hot fluid media, such as internal combustion engines, furnaces, smelters, or applications involving process heat, such as chemical and industrial processes, high temperatures can damage the measuring device. Here, the thermal energy of the fluid medium is transferred to the measuring device through the membrane, potentially damaging or at least hindering the device from determining pressure. Many piezoelectric measuring devices exhibit pyroelectric effects, which, in addition to mechanically induced piezoelectric charge separation, produce additional pyroelectric charge separation that adversely interferes with pressure measurement. The temperature level that damages the measuring device depends on the type of device. This can be remedied by placing the measuring device at a greater distance, for example, by using a very long plunger or long hydraulic line for pressure transmission. However, such solutions are space-consuming. Furthermore, long plungers or long hydraulic lines can affect the sensor's natural frequency.

[0005] In particular, the temperature peaks that occur may damage the measuring device.

[0006] EP0145146A2 discloses a pressure sensor having a diaphragm whose membrane surface faces a fluid medium in a combustion zone and bends in response to the magnitude of adjacent pressure. A second diaphragm is spaced apart from the first diaphragm and bends in response to the bending of the first diaphragm. The second diaphragm is designed to generate a signal indicating the bending of the second diaphragm. The force transmission device, or pressure transmission device, can be a liquid or plunger between the first and second diaphragms, which transmits the motion of the first diaphragm to the second diaphragm and reduces heat transfer from the first diaphragm to the second diaphragm through a larger geometric spacing. A disadvantage here is that the pressure sensor is significantly larger than a corresponding sensor without a first diaphragm and a force transmission device. Summary of the Invention

[0007] The object of this invention is to improve the membrane to reduce the aforementioned disadvantages. Another object of this invention is to provide a membrane that can delay the transfer of heat energy through the membrane.

[0008] The objective of this invention is achieved through the technical solution described herein.

[0009] This invention relates to a heat-insulating membrane for a pressure sensor used to determine the pressure of a fluid medium in a first space; wherein the heat-insulating membrane is designed to separate the first space from a second space. The heat-insulating membrane is substantially parallel to the membrane plane. The membrane plane is defined by the first spatial axis and the second spatial axis. The first and second spatial axes are linearly independent and form a two-dimensional coordinate system. A third spatial axis is arranged perpendicular to the membrane plane. The first, second, and third spatial axes form a three-dimensional coordinate system. The heat-insulating membrane has a membrane body and a coating. When using the heat-insulating membrane, one surface of the membrane body faces the fluid medium. The coating is disposed on this membrane surface.

[0010] According to the present invention, the coating has a lamellar structure. In the case of multiple lamellars, the longitudinal extension of a lamellar perpendicular to the film plane is at most half of its transverse extension parallel to the film plane. Thus, the transverse-to-longitudinal ratio of the lamellar is at least 2, wherein the transverse direction is parallel to the film plane, and the longitudinal direction is parallel to a third spatial axis.

[0011] A lamellar structure refers to a structure primarily composed of lamellars. Lamellars are flattened particles with a transverse-to-longitudinal ratio of at least 2, and are primarily separated from other lamellars by boundaries (e.g., cavities). Cavities may be one or more cavities or one or more gaps between lamellars. Therefore, a coating can be described as a hybrid material having cavities and lamellars.

[0012] "Mainly composed of lamellars" means that at least 50% of the particles exist in the form of lamellars. "Mainly separated" means that the lamellars are separated from other lamellars by boundaries on more than 50% of their surface; however, the lamellars may be at least partially connected by material fit and / or force fit and / or form fit. The term "and / or" should be understood as a non-exclusive logic, also known as "inclusive OR". In a lamellar structure, the lamellars are stacked on top of each other such that the lamellars are arranged substantially parallel with their longer extensions. Here, "substantially parallel" means that the deviation of the longer extension direction of the lamellars is less than 30°.

[0013] The advantage of this layered structure lies in its low thermal conductivity, at least 50% lower than that of the coated film. Thermal conductivity is standardized here in units of length, expressed in W. (mK) -1 (Watts per meter and per Kelvin). Thermal conductivity here refers not to a single layer, but to the overall thermal conductivity at a macroscopic level.

[0014] In this hybrid material, heat propagates primarily along the longer extension of the lamellar structure. Therefore, the hybrid material with the lamellar structure exhibits direction-dependent thermal conductivity, conducting heat better along the longer extension of the lamellars than along the shorter extension. However, the overall thermal conductivity of the hybrid material is significantly lower in any direction than that of a solid (Festkörper) made of the same material as the lamellars. A solid is understood here as an object with the same chemical composition as the lamellars but without cavities.

[0015] Therefore, a heat-insulating membrane, i.e., a membrane with a lamellar coating on its fluid-facing surface, allows for slower heat transfer to the side of the membrane facing away from the fluid medium compared to an uncoated membrane of the same material and size. This allows the membrane to protect the fluid-facing side from high-temperature effects that could damage components for a longer period. Compared to an uncoated membrane, this extends the lifespan of these components, such as measuring devices (e.g., piezoelectric crystals or ceramics, piezoresistive materials, or strain gauges), as well as electronic components, insulators, or other components, particularly those mounted in pressure sensors. Furthermore, it reduces undesirable temperature dependence of the measurement signal, such as that caused by the pyroelectric effect of some piezoelectric measuring elements. The lamellar coating also protects the membrane material itself from temperature peaks. Therefore, the coating also advantageously slows down heat transfer to the membrane itself.

[0016] Here, the coating with a layered structure is more flexible than the corresponding solid made of the same material. Therefore, the coating can be used in flexible elements, such as membranes for pressure sensors, without significantly reducing the flexibility of the insulating membrane, especially compared to a membrane with a coating of the same thickness made of the same material. Preferably, the elastic modulus of the coating and the elastic modulus of the membrane are on the same order of magnitude.

[0017] Advantageously, the layers are substantially separated from each other. The coating has cavities. A cavity is a pore, gap, or crack / microcrack with a length of at least 0.2 μm and at least partially separates the layers from each other. The cavity may contain air or other fluid media, or have a chemical composition different from the layers. This separation is achieved at least partially through the cavities in the coating. Here, the cavities separate the individual layers from each other, such that thermal conduction from one layer to the next is reduced relative to the corresponding solid.

[0018] Thermal insulation films, like the membranes commonly found in pressure sensors, are typically flat elements along the membrane plane. The third axis perpendicular to the membrane plane is also called the longitudinal axis. A characteristic of the lamellar structure of the coating is that most of the lamellars are flat. The lateral extension (extension in the transverse direction, i.e., extension parallel to the membrane plane) of the flat lamellar projection onto the membrane plane is at least twice the longitudinal extension of the lamellar projection onto the third axis (longitudinal axis). Here, lateral and longitudinal extensions are determined according to ASTM E 3 (Standard Guidelines for Metallographic Specimen Preparation) in conjunction with microscopic techniques (e.g., optical microscopy, scanning electron microscopy (REM), etc.).

[0019] This coating can be advantageously applied via a thermal spraying process. In this process, at least partially molten material particles impact the film surface, thereby mechanically flattening and deforming the particles into laminations that solidify on the film surface or onto previously applied laminations. By applying at least partially molten particles onto the solidified laminations, not only is a full material fit bond formed, but also a force fit / form fit bond, which is formed through cavities (such as gaps or pores) that primarily separate the laminations from each other. Accordingly, the cavities extend particularly parallel to the film plane. The particle size is between 5 µm and 120 µm, determined by laser diffraction.

[0020] Specifically, thermal spraying refers to plasma spraying that conforms to DIN EN ISO 14917:2017 Thermal spraying - Terminology, classification (ISO 14917:2017).

[0021] Advantageously, the membrane is made of a metallic material. Metallic materials generally have inherently higher temperature resistance. Particularly advantageously, the membrane is made of a nickel-based alloy or a cobalt-based alloy, as is common in pressure sensors used to determine high temperatures. Here, the membrane particularly advantageously has a chromium content of greater than 15 Gew.% (15 weight percent).

[0022] Advantageously, the coating has a thickness of at least 100 μm. The coating thickness, or simply thickness, is determined perpendicular to the film plane. Generally, the coating thickness should be understood as perpendicular to the surface being coated. Such a coating slows heat transfer to the side facing away from the fluid medium, i.e., the second space, by at least 10% compared to an uncoated identical film.

[0023] In one embodiment of the heat insulation film, the coating has a metallic material, preferably a nickel-based self-fluxing alloy. Nickel-based self-fluxing alloys and their equivalent self-fluxing alloys in the field of thermal spraying are described in DIN EN ISO 14920:2015. Preferably, the coating is made of nickel, chromium, silicon, and boron, particularly preferably with Ni in a weight percentage (empirical formula). 76 Cr 15 The Si5B4 is prepared according to a specific formula. Alternatively, the coating has a nickel alloy, whose main component is nickel and has a high proportion of oxide forming agents, such as aluminum, chromium and yttrium; or the coating has a cobalt alloy, whose main component is cobalt and has a high proportion of oxide forming agents, such as aluminum, chromium and yttrium.

[0024] In another alternative embodiment of the heat insulation film, the coating has a ceramic material, preferably yttrium-stabilized zirconia. Here, the yttrium-stabilized zirconia has at least 90 Gew% zirconia (ZrO2) and 6 Gew% to 8 Gew% yttrium oxide (Y2O3).

[0025] Alternatively, the coating of the heat insulation film may also have the aforementioned metallic and ceramic materials. This can be manufactured, for example, by melting both the metallic and ceramic material particles at least partially and impacting them onto the surface to be coated (hereinafter referred to as the coating surface) and curing them there.

[0026] Preferably, in one embodiment of the heat insulation film, an adhesion layer is disposed between the film surface and the coating. The adhesion layer has a nickel-based and / or cobalt-based and / or iron-based alloy, wherein the nickel-based and / or cobalt-based and / or iron-based alloy has an additional element with a high affinity for oxygen, such as aluminum and refractory metals. The molar standard enthalpy of formation (standard enthalpy of formation of solid oxides at 298.15 K and 1 atm) of these additional elements must have a high affinity for oxygen of less than -150 kJ / mol. Here, the molar standard enthalpy of formation and the affinity for oxygen are based on information published by Boettinger, W., Kattner, U., Moon, K. and Perepezko, J. (2006), NIST Recommended Practice Guide: DTA and Heat-Flux DSC Measurements of Alloy Melting and Freezing, Elsevier, Kidlington. The adhesion layer is applied, for example, by thermal spraying and has a substantially anisotropic structure. An adhesion layer is advantageous because it improves the adhesion of coatings with a lamellar structure compared to an insulating film with the coating applied directly to the membrane. The adhesion layer can, for example, reduce the difference in the coefficients of thermal expansion between the insulating layer and the membrane.

[0027] Preferably, the linear thermal expansion coefficient (hereinafter referred to as the membrane expansion coefficient) of the membrane in the temperature range of 20℃ to 100℃ is 8.10- 6 K- 1 Up to 15.10 -6 K -1 Preferably, the difference between the linear coefficient of thermal expansion of the coating (referred to as the coating expansion coefficient) and the coefficient of thermal expansion of the film is less than 40%. This is advantageous because significantly different (greater than 40%) linear expansion coefficients can lead to high stress between the film and the coating, especially when the film is exposed to significantly different temperatures, such as during storage compared to use in high-temperature applications. This stress can cause the coating to peel off, negatively impacting or damaging the insulation performance of the film. Therefore, adjusting the film expansion coefficient to a maximum deviation of 40% from the coating expansion coefficient is beneficial for the temperature resistance of the coating.

[0028] Advantageously, the coating has thermal conductivity in the film plane and thermal conductivity perpendicular to the film plane. Preferably, the thermal conductivity in the film plane is greater than the thermal conductivity perpendicular to the film plane. Thus, in addition to the reduced thermal conductivity through the cavities of the lamellar structure, heat transfer to the second space is also slowed down by making it more difficult for heat energy to be conducted to the film along the longitudinal axis, as it is mainly discharged laterally along the film plane.

[0029] Typically, the film also exhibits thermal conductivity. The thermal conductivity of the film is greater than that of the coating in any direction.

[0030] The present invention also relates to a sensor for determining the pressure of a fluid medium. The sensor has an insulating membrane according to one of the above embodiments. The sensor has a pressure-side end facing the fluid medium. The sensor has a housing. The sensor also has a measuring device. The fluid medium applies pressure to the insulating membrane, which is in effective connection with the measuring device. The insulating membrane slows down the heat transfer from the fluid medium to the inner cavity of the housing, which is typically a second space, separated from a first space containing the fluid medium by the membrane.

[0031] Advantageously, a heat-insulating film is arranged on the pressure-side end of the sensor, facing the fluid medium. The measuring device is hermetically separated from the fluid medium by the heat-insulating film. This is preferably achieved through a material fit between the housing and the heat-insulating film. The housing may have at least a partial housing coating that is identical to and transitions into the coating of the heat-insulating film. This has the advantage that heat transferred through the housing into the second space, or through the housing portion facing the fluid medium, is also slowed down. The coating can be applied to the housing surface accordingly. An adhesive layer can be pre-applied to the housing surface, similar to the corresponding embodiment of the heat-insulating film.

[0032] The sensor according to the invention is manufactured, for example, by performing at least the following steps. However, manufacturing is not limited to the methods listed herein, and can also be achieved by other techniques besides thermal spraying, such as 3D printing, laser cladding welding, etc.

[0033] Manufacturing a sensor including a heat-insulating membrane comprises at least the following sub-steps: providing a housing having a membrane body disposed on the pressure-side end of the sensor; determining a coating surface, wherein the coating surface includes at least the membrane surface; the coating surface may be pre-roughened by sandblasting, glass bead blasting, or similar methods, depending on the surface condition; applying the coating to the coating surface by thermal spraying; metal or ceramic particles moving along the direction of the coating surface; the particles being at least partially melted and impacting the coating surface in a at least partially melted state; the particles undergoing lamellar deformation due to the kinetic energy of their impact; these particles primarily solidifying into lamellar shapes and forming lamellar structures within the coating.

[0034] Optionally, manufacturing a sensor with a heat-insulating film may also include the step of coating the surface of the housing (referred to as the housing surface).

[0035] Optionally, manufacturing a sensor with a heat-insulating film may also include the following step: in which the coating surface is preferably provided with an adhesion layer at least partially, wherein the adhesion layer is consistent with the adhesion layer in the corresponding embodiment of the heat-insulating film. Attached Figure Description

[0036] The present invention will now be described in detail by way of example with reference to the accompanying drawings.

[0037] Figure 1 A schematic diagram of a sensor with a heat-insulating film is shown.

[0038] Figure 2 A schematic cross-sectional view of a sensor having a heat-insulating film according to a first embodiment is shown.

[0039] Figure 3 A schematic cross-sectional view of a sensor having a heat-insulating film according to another embodiment is shown.

[0040] Figure 4 A schematic cross-sectional view of a sensor having a heat-insulating film according to another embodiment is shown.

[0041] Figure 5 A schematic cross-sectional view of a sensor having a heat-insulating film according to another embodiment is shown.

[0042] Figure 6 It shows that according to Figure 2 or Figure 3 Detail A of the heat insulation film in the illustrated embodiment.

[0043] Figure 7 It shows that according to Figure 4 or Figure 5 Detail B of the heat insulation film in the illustrated embodiment.

[0044] Figure 8 A detail of the heat insulation film, C, is shown.

[0045] Figure 9 A schematic diagram of the manufacturing process of the heat insulation film is shown.

[0046] Figure 10 It shows that according to Figure 4 or Figure 5 Detail B of the heat insulation film of another embodiment shown.

[0047] Figure 11 A schematic cross-sectional view of a sensor having a heat-insulating film according to another embodiment is shown.

[0048] Figure 12 A schematic cross-sectional view of a sensor having a heat-insulating film according to another embodiment is shown.

[0049] List of reference numerals

[0050] 1: Sensor, pressure sensor

[0051] 2: Heat insulation film

[0052] 3: Membrane

[0053] 4: Additive layer

[0054] 5: Coating

[0055] 6: Membrane surface

[0056] 7: Layered structure

[0057] 8: Cavity, hole, gap

[0058] 9: Layers

[0059] 10: Pressure side end

[0060] 11: Material matching and connection

[0061] 12: Shell

[0062] 13: Measuring devices, sensors

[0063] 14: Shell Coating

[0064] 15: Coated surface

[0065] 16: Shell surface

[0066] 17: Coating thickness, layer thickness, thickness

[0067] 18: Thickness of the adhesive layer

[0068] DQ: Lateral stretch

[0069] DL: Longitudinal extension

[0070] F: Fluid medium

[0071] P: Particles

[0072] R1: First Space

[0073] R2: Second Space

[0074] X: First spatial axis, first horizontal axis

[0075] XY: Membrane plane

[0076] Y: Second spatial axis, second horizontal axis

[0077] Z: Third spatial axis, longitudinal axis Detailed Implementation

[0078] Figure 1A sensor 1 with a heat-insulating membrane 2 is shown schematically. The sensor 1 is designed to determine the pressure of a fluid medium F in a first space R1. The sensor 1 has a pressure-side end 10 facing the fluid medium F. Furthermore, the sensor 1 has a housing 12. The sensor 1 has a measuring device 13, located inside the sensor and within… Figure 1 The measuring device is not visible in the center. It is arranged in a second space R2 inside the housing 12. A heat-insulating membrane 2 is arranged at the pressure-side end 10. The sensor extends along a third axis Z (also called the longitudinal axis Z). The heat-insulating membrane 2 is substantially parallel to the membrane plane (XY), which is given by the first spatial axis X and the second spatial axis Y, the second spatial axis extending into the drawing. The heat-insulating membrane is shown as a membrane body 3 with a coating 5 (shown in dashed lines).

[0079] Figure 2 A schematic cross-sectional view shows details of a sensor 1 having a heat-insulating membrane 2 according to a first embodiment. The heat-insulating membrane 2 has a membrane body 3 and a coating 5. When using the heat-insulating membrane 2 or the sensor 1, the membrane surface 6 of the membrane body 3 faces the fluid medium F. The coating 5 is disposed on the membrane surface 6.

[0080] All embodiments shown in the accompanying drawings are schematic diagrams. Dimensions, particularly thickness, coating thickness, length, etc., are chosen for better visibility only and should not be construed as an illustration of component dimensions or relative dimensions between components.

[0081] Figure 2 A schematic cross-sectional view of a sensor 1 having a heat-insulating film 2 according to a first embodiment is shown. This schematic cross-sectional view shows... Figure 1 A partial cross-sectional view of sensor 1 along the first axis X and the third axis Z. Within housing 12, a measuring device 13 is arranged in a second space R2. This measuring device, for example, has a piezoelectric crystal or piezoelectric ceramic, or other piezoresistive material or strain gauge, effectively connected to the diaphragm 3, which generates a measurable electrical signal when subjected to force or pressure. The insulating diaphragm 2 has a diaphragm 3 and a coating 5. As is common in sensor 1, the diaphragm 3 is arranged at the pressure-side end 10 of sensor 1 and is connected to the sensor housing 12, for example, by a material-fit connection 11 (e.g., welded connection, brazed connection, etc.). However, the diaphragm 3 can also be constructed as a single piece with housing 12; the invention is by no means limited to a two-piece structure, but specifically includes a one-piece structure of diaphragm 3 and housing 12. The insulating diaphragm 2 is designed to transmit the pressure of the fluid medium F in the first space R1 to the measuring device 13. Therefore, the insulating diaphragm 2 is effectively connected to the measuring device 13. In this embodiment, the coating 5 extends both to the membrane 2 and to a portion of the housing 12, and is a portion that seamlessly transitions from the membrane 2 to the housing. It should be understood that the sheet 9, as it is in... Figure 6 and Figure 8As shown, the lateral extensions DQ of the layers are oriented substantially parallel to the coated surface 15, and thus the spatial direction of the lateral extensions changes as the layers transition from the film surface 6 to the surface of the housing 12. While the lateral extensions of the sheets 9 on the film surface are substantially parallel to the first axis X and the second axis Y (in... Figure 2 (perpendicular to the plane of the drawing), but the lateral extension of the layer 9 of the coating of the shell 12 is basically parallel to the third axis Z.

[0082] In this and subsequent embodiments of the heat insulation film 2, the same reference numerals in these embodiments denote the same elements.

[0083] Figure 3 A schematic cross-sectional view of a sensor 1 having a heat-insulating film 2 according to another embodiment is shown. This embodiment is similar to... Figure 2 The only difference in the illustrated embodiment is coating 5. Figure 3 In this embodiment, coating 5 extends to the membrane surface 6. The housing 12 has no coating. This is particularly advantageous for front-sealed sensors, in which the fluid medium does not contact the housing 12 or only contacts it in a very small portion during sensor 1 use.

[0084] Figure 4 A schematic cross-sectional view of a sensor 1 having a heat-insulating film 2 according to another embodiment is shown. In this embodiment of the heat-insulating film 2, the same reference numerals denote the same elements as in the previously shown embodiments. In this embodiment, an additional adhesion layer 4 is applied between the coating 5 and the film body. The adhesion layer 4 improves the adhesion of the coating 5 to the film body 3. The adhesion layer 4 is optional and can be omitted for economic reasons if the adhesion of the coating 5 to the film body 3 is sufficient for a particular application. In this embodiment, the adhesion layer 4 extends not only to the film surface 6 but also to the housing surface 16. Therefore, the adhesion layer 4 is disposed between the coating surfaces 6, 15 and the coating 5.

[0085] Figure 5 A schematic cross-sectional view of a sensor 1 having a heat-insulating film 2 according to another embodiment is shown. In this embodiment of the heat-insulating film 2, the same reference numerals also denote... Figures 2 to 4 The same components are used in the embodiments shown. Figure 5 Implementation methods and Figure 4 The only difference in the implementation method is the coating 5 and the adhesion layer 4. Figure 5 In this embodiment, both the adhesion layer 4 and the coating 5 extend onto the film surface 6. The housing 12 has no coating. This is similar to... Figure 3 The implementation of the heat insulation film 2 is particularly advantageous for front-sealed sensors, in which the fluid medium does not contact the housing 12 or only contacts it in a very small part during the use of the sensor 1.

[0086] Figure 6 The diagram schematically illustrates a detail A of coating 5, which schematically shows the application of... Figure 2 The coating 5 of the heat insulation film 2 in the illustrated embodiment is also shown for use in... Figure 3 The coating 5 of the heat insulation film 2 in the embodiment shown. Figure 2 and Figure 3 The cross-section of detail A is shown in the corresponding diagram. Figure 6 and Figure 8 The sheets 9 shown are arranged on the film 3. It should be noted that this is only a schematic diagram and does not constitute a limitation on the number of sheets 9, their lateral stretch (DQ) or longitudinal stretch (DL), or their ratio. According to the invention, the ratio of the lateral stretch (DQ) to the longitudinal stretch (DL) of most sheets 9 is at least 2. The coating 5 has cavities 8 that substantially space the sheets 9 apart from each other. The coating 5 is indicated by a coating thickness 17, which is perpendicular to the coating surface and measured from the film 3.

[0087] Figure 7 The diagram schematically illustrates a detail B of coating 5, which schematically shows the application of... Figure 4 The coating 5 of the heat insulation film 2 in the illustrated embodiment is also shown for use in... Figure 5 The coating 5 of the heat insulation film 2 in the embodiment shown. Figure 4 and Figure 5 The cross-section of detail B is shown in the corresponding diagram. Figure 7 and Figure 8 The sheet 9 shown is arranged on the film 3. It should be noted that this is only a schematic diagram and does not limit the number, lateral or longitudinal extension, or ratio of the sheets 9. According to the invention, the ratio of the lateral extension DQ to the longitudinal extension DL of most sheets is at least 2. The coating 5 has cavities 8 that substantially space the sheets 9 apart from each other. Cavities 8 are, for example, holes 8 or gaps 8, such as… Figure 7 The diagram is schematic. An adhesion layer 4 is arranged between the coating 5 and the film 3. The illustrations of the adhesion layer 4 and the cavity 8 are also schematic and do not represent dimensions or size proportions relative to the film 3 or the sheet 9. Figure 7 In this process, the reinforcing layer 4 also has a layered structure. The reinforcing layer 4 can also be applied by a thermal spraying process similar to that of coating 5, and differs from coating 5 only in its material. Figure 7 The purely illustrative illustrations here explicitly disallow any representation of scale. Coating 5 is represented by coating thickness 17, which is perpendicular to the coating surface and measured starting from the adhesion layer 4. Coating thickness 17 refers to the average thickness of coating 5. The thickness of the adhesion layer 18 is measured similarly to coating thickness 17 and can be determined using the same method.

[0088] exist Figure 10The diagram schematically illustrates an alternative adhesion layer. This adhesion layer does not have a layered structure and can be applied, for example, by vapor deposition, other physical vapor deposition techniques, or by laser cladding welding, or produced by a self-fused gold layer applied by sintering thermal spraying.

[0089] It should be pointed out that, of course, it is also possible to... Figure 4 , Figure 5 , Figure 7 and Figure 10 At least one additional layer is disposed between the coating layer 4 and the membrane 3. The coating layer 4 need not be in direct contact with the membrane 3 in any way.

[0090] Figure 8 The diagram schematically illustrates a detail C of coating 5, which schematically shows the application of... Figure 6 The coating 5 of the heat insulation film 2 in the illustrated embodiment and for use Figure 7 The coating 5 of the heat insulation film 2 in the embodiment shown. Figure 6 and Figure 7 The cross-section of detail C is shown in the corresponding diagram. Figure 8 The diagram illustrates how to determine the longitudinal stretch DL and transverse stretch DQ of sheet 9. Figure 8 The sheet 9 of the lamellar coating 5 is shown in cross-section. However, the lateral extension DQ of the sheet 9 is substantially the same in any direction parallel to the film plane XY. The sheet 9 has a generally flattened oval shape, and its lateral extension DQ is relatively long. The longitudinal extension DL is defined here perpendicular to the coating surface 15. The lateral extension DQ is defined here parallel to the coating surface 15. If the coating 5 is arranged on the film surface 6, with an adhering layer 4 located therein if necessary, the lateral extension is parallel to the film plane XY, while the longitudinal extension is parallel to the third axis Z (also called the longitudinal axis Z).

[0091] Figure 7 The attachment layer 4 in the illustrated embodiment is generally similar to Figure 8 The coating consists of 5 parts, with the main difference being the choice of materials.

[0092] In all the embodiments shown, most of the sheets 9 are configured to be flat, such that the lateral extension DQ of the projection of the flat sheet 9 onto the film plane XY is at least twice the longitudinal extension DL of the projection of the sheet onto the third axis Z (referred to as the longitudinal axis Z).

[0093] In all the embodiments of the heat insulation film 2 shown, the coating 5 has a coating thickness 17 of at least 100 μm. The coating thickness 17 of the coating 5 is measured perpendicular to the coating surface 15. It is perpendicular to the film plane XY in the coating 5 on the film surface 5, and correspondingly perpendicular to the respective housing surface 16 in the coating of the housing 12.

[0094] The coating 5 of all illustrated embodiments of the heat insulation film 2 can be applied by a thermal spraying process, such as... Figure 9 As shown schematically in the diagram.

[0095] Manufacturing a sensor 1 having a heat-insulating film according to any of the embodiments described includes at least the following sub-steps, which are partially described in... Figure 9 The diagram is shown schematically. Figure 9 The provided membrane 3 is shown, which is arranged on the sensor 1 (not shown, similar to) Figure 1 At the pressure-side end 10 (not shown). A coating surface 15 is defined, which in this exemplary example includes at least a film surface 6. The coating 5 is applied to the coating surface 15 by thermal spraying, wherein metal or ceramic particles P move along the direction of the coating surface 15, as indicated by arrows on the particles P. The particles P are at least partially melted and impact the coating surface 15 in a at least partially melted state. The particles P undergo lamellar deformation by the kinetic energy of their impact and solidify primarily into a lamellar shape, forming lamellar 9 in the lamellar structure 7 of the coating 5.

[0096] The embodiments of the heat insulation film 2 disclosed herein can, of course, be combined with each other. Embodiments having combinations of features described herein are also explicitly included herein.

[0097] In particular, there is also an embodiment of the sensor 1 with a heat-insulating film 2, wherein the adhesion layer 4 is arranged between the film 3 and the coating 5, but the adhesion layer 4 is not arranged between the housing 12 or the housing surface 16 and the coating 5, such as... Figure 11 As illustrated schematically. Alternatively, there may be an embodiment of the sensor 1 with a heat-insulating film 2, wherein the adhesion layer 4 is disposed between the housing 12 or the housing surface 16 and the coating 5, but no adhesion layer 4 is disposed between the film 3 and the coating 5, as shown in the schematic. Figure 12 As shown schematically in the diagram.

Claims

1. A heat-insulating membrane (2) for a pressure sensor (1) used to determine the pressure of a fluid medium (F) in a first space (R1); wherein, The heat insulation film (2) is designed to separate the first space (R1) from the second space (R2); wherein the heat insulation film (2) is constructed substantially parallel to the film plane (XY); the film plane (XY) is given by the first spatial axis (X) and the second spatial axis (Y); wherein the third spatial axis (Z) is arranged perpendicular to the film plane (XY); wherein the heat insulation film (2) has a film body (3) and a coating (5); wherein, when the heat insulation film (2) is used, the film surface (6) of the film body (3) faces the fluid medium (F); wherein the coating (5) is disposed on the film surface (6); characterized in that the coating (5) has a lamellar structure (7); the coating has lamellar sheets (9), and for most of the lamellar sheets (9), the longitudinal extension (DL) of the lamellar sheet (9) perpendicular to the film plane (XY) is at most half of the lateral extension (DQ) of the lamellar sheet (9) parallel to the film plane (XY).

2. The heat insulation film (2) according to the preceding claim, characterized in that, The coating has cavities (8) in the form of, for example, holes; the layers (9) are substantially separated from each other; wherein the separation is achieved at least in part through the cavities (8) in the coating (5).

3. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The majority of the sheets (9) are configured to be flat, such that the lateral extension (DQ) of the projection of the flat sheets (9) onto the film plane (XY) is at least twice the longitudinal extension (DL) of the projection of the sheets onto the third axis (Z), which is simply referred to as the longitudinal axis (Z).

4. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The coating (5) is applied by a thermal spraying process.

5. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The membrane (3) is made of a metallic material; or the membrane (3) is made of a nickel-based alloy or a cobalt-based alloy, wherein the membrane (3) has a chromium content of more than 15 Gew.%.

6. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The coating (5) has a coating thickness (17) of at least 100 μm, which is simply referred to as thickness (17); wherein the coating thickness (17) of the coating (5) is perpendicular to the film plane (XY).

7. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The coating (5) has a metallic material, preferably a nickel-based self-fluxing alloy, or a nickel alloy with a high proportion of oxide forming agents, such as aluminum, chromium and yttrium, or a cobalt alloy with a high proportion of oxide forming agents, such as aluminum, chromium and yttrium.

8. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The coating (5) has a ceramic material, such as yttrium-stabilized zirconium oxide; or the coating (5) has a metallic material and a ceramic material.

9. The heat insulation film (2) according to any one of the preceding claims, characterized in that, An adhesion layer (4) is disposed between the film surface (6) and the coating (5); the adhesion layer (4) has a nickel-based and / or cobalt-based and / or iron-based alloy; wherein the nickel-based and / or cobalt-based and / or iron-based alloy has an additional element with a high affinity for oxygen, such as aluminum and refractory metals; wherein the standard enthalpy of formation of the additional element must have a high affinity for oxygen of less than -150 kJ / mol.

10. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The membrane (3) has an 8·10- Ω·m / ℃ temperature range of 20℃ to 100℃. 6 K- 1 Up to 15.10 -6 K -1 The linear thermal expansion coefficient is referred to as the film expansion coefficient; the coating (5) has a linear thermal expansion coefficient, referred to as the coating expansion coefficient; and the difference between the coating expansion coefficient and the film expansion coefficient is less than 40%.

11. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The coating (5) has thermal conductivity in the film plane (XY); the coating (5) has thermal conductivity perpendicular to the film plane (XY); and the thermal conductivity in the film plane (XY) is greater than the thermal conductivity perpendicular to the film plane (XY).

12. The heat insulation film (2) according to any one of the preceding claims, characterized in that, The coating (5) is thermally conductive in the film plane (XY); the coating is thermally conductive perpendicular to the film plane (XY); the film body (3) is thermally conductive; and the thermal conductivity of the film body (3) is greater than the thermal conductivity of the coating (5) in any direction.

13. A sensor (1) for determining the pressure of a fluid medium (F); wherein, The sensor (1) includes a pressure-side end (10) facing the fluid medium (F); wherein the sensor (1) has a housing (12); wherein the sensor (1) has a measuring device (13); characterized in that the sensor (1) has a heat-insulating film (2) according to any one of the preceding claims.

14. The sensor (1) according to the preceding claim, characterized in that, The heat insulation membrane (2) is arranged on the pressure side end (11) of the sensor (1) and airtightly separates the measuring device (13) from the fluid medium (F); the housing (12) and the heat insulation membrane (2) are connected to each other by a material fitting connection (11); wherein the housing (12) has at least a partial housing coating (14), the housing coating being formed and transitioned therein in the same way as the coating (5) of the heat insulation membrane (2).

15. Manufacturing of the sensor (1) according to claim 13 or 14; wherein the manufacturing comprises at least the following sub-steps: providing a housing (12) having a membrane (3) disposed on the pressure-side end (10) of the sensor (1); determining a coating surface (15), wherein the coating surface (15) comprises at least a membrane surface (6); applying a coating (5, 14) to the coating surface (15) by a thermal spraying process, wherein metal or ceramic particles (P) move along the direction of the coating surface (15); wherein the particles (P) are at least partially melted; wherein the particles (P) impact the coating surface (15) in a state of at least partial melting; wherein the particles (P) undergo lamellar deformation by the kinetic energy of their impact; wherein the particles (P) are primarily solidified into lamellar structures and form the lamellar structure (7) of the coating (9).

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