Diaphragm for use in hydrogen-containing fluid media and transducer equipped with this diaphragm

Abstract

The present invention relates to a diaphragm (2) for hermetically separating a first space (14) containing a hydrogen-containing fluid medium (13) from a second space (15), the diaphragm (2) comprising a metallic material (3), the diaphragm (2) being provided with a coating (4) which reduces the permeability of the diaphragm (2) to molecular and / or atomic hydrogen, the coating (4) being disposed between the metallic material (3) of the diaphragm (2) and the fluid medium (13) at least in the area which will be in contact with the fluid medium (13) during use, the coating (4) comprising at least one non-stoichiometric oxide, carbide or nitride.

Description

[Technical Field]

[0001] The present invention relates to a diaphragm for use in a hydrogen-containing fluid medium, and a transducer equipped with the diaphragm. [Background technology]

[0002] A diaphragm separates a fluid medium in a first space from a second space. In the field of pressure measurement technology, transducers often include a diaphragm. The diaphragm separates the measuring device (e.g., the transducer element) from the fluid medium whose pressure is to be determined. The fluid medium is a gaseous medium and / or a liquid medium. For this purpose, the diaphragm usually has a surface having first and second dimensions, the first and second dimensions extending substantially in a direction perpendicular to the longitudinal axis. In the third dimension extending parallel to the longitudinal axis, the diaphragm has a thickness also called the wall thickness.

[0003] In the following, "fluid medium" is understood to mean a hydrogen-containing fluid medium that contains at least 1 volume% of hydrogen.

[0004] Generally, the surface of a diaphragm has a region that comes into contact with the fluid medium in the first space. In the case of a pressure transducer, the pressure of the fluid medium acting on the diaphragm region is transmitted to the pressure transducer element (abbreviated as transducer element) with as little loss as possible. The flexibility of the diaphragm region directly exposed to the fluid medium should be as high as possible, or its stiffness should be as low as possible, so that the sensitivity of the measuring device including the transducer element is not significantly affected by the diaphragm. However, the material in this low-stiffness region should not be irreversibly deformed by the measuring pressure. When using a material with a yield strength of approximately 400 MPa (megapascals), the diaphragm needs to be of an appropriate thickness so that it does not deform irreversibly. Furthermore, the diaphragm may have a thicker region, for example, where the diaphragm is connected to the transducer housing. The thicker region also serves to improve the stability of the diaphragm.

[0005] The yield strength of metallic materials is determined by the standard DIN EN ISO 6892-1. P 0.2 It corresponds to a value.

[0006] The surface of the diaphragm may extend substantially along the first and second dimensions, but may be partially curved in the direction of the longitudinal axis.

[0007] A diaphragm can also separate the fluid medium from other types of transducer elements; for example, in a thermal transducer, the thermal transducer element is separated from the fluid medium by a diaphragm. In this case, the temperature of the fluid medium is transferred to the thermal transducer element via the diaphragm. In this case as well, the walls of the diaphragm need to be as thin as possible to obtain the highest possible heat transfer coefficient.

[0008] Generally, corrosion is understood to mean a measurable change in a substance. Corrosion can occur when exposed to various substances. Therefore, the corrosion of metallic materials is well known in relation to various alkalis or acids, gases (such as hydrogen or oxygen), salt water, and many other substances.

[0009] However, hereinafter, unless otherwise specified, corrosion refers to corrosion caused by atomic hydrogen and / or molecular hydrogen.

[0010] When the fluid medium contains hydrogen, the diaphragm needs to have both tightness and resistance to atomic hydrogen and / or molecular hydrogen. For this reason, for example, commercially available hydrogen-resistant polycrystalline metals such as austenitic steel 1.4404 (also known as 316L) with a yield strength of about 400 MPa at room temperature, or nickel-based alloy 2.4819 (also known as C-276) with the same yield strength of about 400 MPa at room temperature, are often used as materials for diaphragms with heat resistance exceeding 200 °C. However, these materials are characterized by an average grain size exceeding 20 μm. Coarse-grained polycrystalline metals have few grains in the thin-wall region of the diaphragm, which may cause the material not to exhibit isotropic behavior, so they are not very suitable as materials for thin diaphragms with a thickness of less than 500 μm. Furthermore, the diffusion paths of molecular hydrogen and / or atomic hydrogen along grain boundaries between grains are relatively short through the coarse-grained region. A short path may allow hydrogen to diffuse easily through the diaphragm, which is disadvantageous.

[0011] Designation 1.4404 and other material numbers described below correspond to DIN EN 10027-2.

[0012] So-called hydrogen embrittlement occurs when molecular hydrogen and / or atomic hydrogen penetrate into a metallic material. As a result, when stress is applied to the material, there is a risk of brittle fracture.

[0013] Hydrogen embrittlement means that hydrogen penetrates into the lattice structure of a metal or alloy and is then incorporated, resulting in changes in the ductility and strength of the metal or alloy. As a result, hydrogen-related cracks may occur, and the use of materials that are susceptible to such effects is restricted in applications where they come into contact with hydrogen.

[0014] It is well known that metals or alloys with high strength are more prone to hydrogen embrittlement than those with low strength.

[0015] Materials such as steel 1.4404 (also known as 316L) and alloy 2.4819 (also known as C-276) are generally considered to be corrosion-resistant. Since they have a low yield strength, they exhibit a high plastic deformation ability even with a smaller force than materials with a high yield strength. To compensate for this drawback, diaphragms are often manufactured with a thickness exceeding 500 μm. However, thick diaphragms are disadvantageous because they have a large inertial mass. Furthermore, in the case of thick diaphragms, the rigidity is also higher.

[0016] In a known embodiment, the pressure transducer has a space behind a diaphragm filled with a fluid pressure transmission medium. In this embodiment, since the fluid pressure transmission medium resists the deformation of the diaphragm, the risk of the diaphragm undergoing irreversible plastic deformation is reduced. The fluid pressure transmission medium (e.g., oil with a low compressibility) transmits the pressure acting on the diaphragm to a measuring element spaced apart from the diaphragm. Furthermore, the diaphragm is required to transmit the pressure with as little loss as possible, that is, it is advantageous for the diaphragm to be made thin. When the fluid medium to be measured contains hydrogen, hydrogen accumulates in the fluid pressure transmission medium over time, and its volume increases, causing the diaphragm to bulge outward. The diaphragm expands due to hydrogen diffusing through the diaphragm. This can damage the diaphragm on the one hand and change the pressure conditions near the measuring element on the other hand. When molecular hydrogen and / or atomic hydrogen diffuse through the diaphragm, it has an adverse effect on the long-term stability of the transducer.

[0017] Patent Document 1 describes a transducer with a diaphragm made of alloy 2.4819 (also known as C-276). While the material itself is considered corrosion-resistant, the thinness of the diaphragm means it is not impermeable to hydrogen. Depositing a soft gold layer on the diaphragm prevents the diffusion of molecular and / or atomic hydrogen. Because the gold layer is substantially chemically inert, the dissociation of molecular components from the fluid medium in contact with the diaphragm is reduced. Dissociation of molecular components of the fluid medium, or other chemical reactions on and with the surface, can lead to surface corrosion. However, due to the low strength of gold, the soft gold layer is not scratch-resistant and may be damaged during use, after which it may no longer function as a diffusion barrier against hydrogen. [Prior art documents] [Patent Documents]

[0018] [Patent Document 1] U.S. Patent Application Publication No. 2005 / 0109114 [Overview of the project] [Problems that the invention aims to solve]

[0019] An object of the present invention is to improve the diaphragm to mitigate the aforementioned drawbacks. A further object of the present invention is to improve the corrosion resistance of the diaphragm to atomic hydrogen and / or molecular hydrogen. [Means for solving the problem]

[0020] This objective was achieved by the configuration of the independent claim.

[0021] The present invention relates to a diaphragm for hermetically separating a first space containing a hydrogen-containing fluid medium from a second space. The diaphragm comprises a metallic material. The diaphragm is provided with a coating for reducing the permeability of molecular hydrogen and / or atomic hydrogen, the coating deposited between the metallic material of the diaphragm and the fluid medium, at least in the area that comes into contact with the fluid medium during use. The coating comprises oxides, carbides, or nitrides, such as aluminum oxide, aluminum carbide, aluminum nitride, chromium oxide, chromium nitride, silicon oxide, silicon carbide, silicon nitride, titanium oxide, titanium carbide, titanium nitride, zirconium oxide, rare earth carbides or nitrides, or rare earth oxides.

[0022] According to the present invention, the coating comprises at least one non-stoichiometric oxide, carbide, or nitride.

[0023] Preferably, the coating contains a non-stoichiometric mixture.

[0024] For example, a diaphragm is a diaphragm used in a transducer to determine the pressure of a fluid medium.

[0025] Preferably, the metallic material is an alloy containing at least one metal-containing chemical element and at least one other chemical element.

[0026] The diaphragm is used to separate the space containing the hydrogen-containing fluid medium from other spaces. The hydrogen-containing fluid medium contains at least 1 volume percent of hydrogen and is also referred to as a corrosive fluid medium in the following text.

[0027] The metal material of the diaphragm is composed of metal or alloy. Examples of metals or alloys include nickel-based alloys (e.g., electroformed nickel, nickel-270, nickel-301, K-Monel), titanium-based alloys (e.g., pure titanium, Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-11.5Mo-6Zr-4.5Sn, alpha-2TiAl alloy, gamma-TiAl alloy), or copper-based alloys (e.g., OFHC copper, aluminum). Bronze, Be-Cu alloy, GRCop-84 (Cu-8Cr-4Nb), NARloy-Z (Cu-3Ag-0.5Zr), 70-30 brass), or aluminum-based alloys (e.g., 1100-T0, 2011, 2024, 5086, 6061-T6, 6063, 7039, 7075-T73), or austenitic steel (e.g., CG-27, Tenelon, A302B, A286, 216, 304L, 304N, 304LN, 305, 308L, 309S, 310, 316, 321, 347, 18-2-12 (Nitronic32), 21-6-9 (Nitronic40), 22-13-5 (Nitronic50), 18-18Plus, 18-2-Mn, 18-3-Mn), or ferritic steel (e.g., A106-Gr.B, A212-61T, A 372, A515-Gr.70, A516, A517-F(T-1), A533B, HY-80, HY-100, iron (Armco), X42, X52, X60, X65, X70, X100, 430F, 1020, 1080, C1025, 1042, 4140, 4340), or martensitic steel (e.g., AerMet100, D6AC, H-11, Fe-9Ni-4Co-0).20C, 410, 440A, 440C, 17-4PH, 18Ni-250), or nickel-based superalloys (superalloys) (e.g., AF-115, AF-56, Astroloy, CM SX-2, CM SX-3, CM SX-4C, CM SX-4D, CM-SX5, Hastelloy, Haynes 230, Haynes 242, IN100, Inconel 625, Inconel 700, Inconel 706, Inconel 713LC, Inconel 718, Inconel X-750, Inco 4005, MAR-M200, MAR-M246, MA 6000, MA 754, MERL 76, NASA-HR1, PWA 1480, PWA 1480E, Rene 41, Rene N-4, Rene 95, RR These include iron-based superalloys (e.g., A286, Incoloy 802, Incoloy 901, Incoloy 903, Incoloy 907, Incoloy 909, JBK-75, MA 956, Ni-SPAN-C) or cobalt-based superalloys (e.g., Haynes 188, MP35N, MP159, MP98T, X-45). These alloys are described in more detail in JALee, Hydrogen Embrittlement, NASA / TM-2016-218602, Alabama, USA (2016), Tables 2, 3, and 4. In principle, alloys are suitable as metallic materials for manufacturing diaphragms with various dimensions selected according to their material properties. However, some alloys are only partially suitable for direct exposure to hydrogen-containing fluid media. By coating metal materials, experts can select the appropriate metal material for the diaphragm according to its suitable physical properties, such as rigidity, thermal conductivity, coefficient of thermal expansion, or yield strength. The coating protects the metal material from hydrogen-related corrosion. While hydrogen resistance of the metal material is advantageous, it is not essential.

[0028] As mentioned at the beginning, some of the aforementioned metallic materials have a coarse-grained polycrystalline structure, which makes them less suitable as materials for thin diaphragms less than 500 μm thick that come into direct contact with hydrogen-containing fluid media. However, coating the diaphragm eliminates this drawback, thus broadening the range of materials that can be used as metallic materials for the diaphragm.

[0029] Preferably, the diaphragm has a thickness of less than 500 μm in at least a specific region. This is advantageous in that it transmits the pressure of the fluid medium from the first space to the measuring device located in the second space with as little loss as possible. Furthermore, a diaphragm with a thickness of less than 500 μm exhibits lower inertia than a diaphragm with a greater thickness. This is advantageous because when the transducer is accelerated, only a very small force acts on the measuring device due to the inert mass of the diaphragm, so the pressure measurement is unaffected or only slightly affected by the acceleration.

[0030] Particularly preferred are fine-grained steels having structures of martensite, bainite, needle ferrite, Widmanstättenferrite, or mixtures of these structures. Generally, these are not considered hydrogen-resistant, but surprisingly, their relatively fine-grained structure results in a lower tendency towards hydrogen embrittlement. The fine-grained structure lengthens the diffusion pathways, which is why hydrogen cannot diffuse through these materials over short distances. Therefore, the metallic materials possess a certain resistance to hydrogen. Bainite, needle ferrite, and Widmanstättenferrite are also known as intermediate structures. Intermediate structures include those between martensite and pearlite. Needle ferrite is intended to refer to the material known in English as needle-shaped ferrite.

[0031] The structures of martensite, bainite, Widmanstättenferrite, needleferrite, or mixtures thereof are characterized by an average particle size of less than 20 μm, and are therefore particularly suitable for the manufacture of thin-walled diaphragms with a thickness of less than 500 μm. Due to the small average particle size, these components exhibit isotropic physical properties, which is advantageous when used in diaphragms.

[0032] Particularly preferred is a structure that includes martensite with partially coherent or incoherent precipitates at grain boundaries within the material, as described in Metallkunde, E. Hornbogen and H. Warlimont, 4th edition, Springer Verlag 2001. Partially coherent or incoherent precipitates in the sense of this description are described in Werkstoffkunde-Stahl-Vol. 1, Verein Deutscher Eisenhuttenleute (ed.), Springer Verlag 1984, or in Pirlog, Madalina, and PK Pranzas, “CHARACTERIZATION OF COPPER PRECIPITATES IN FE-CU ALLOYS WITH SMALL-ANGLE NEUTRON SCATTERING.”

[0033] Non-coordinated and partially coordinated precipitates function as hydrogen sinks. Hydrogen accumulates in these sinks, preventing the accumulated hydrogen from further penetrating the material. Coordinated precipitates, being located within the particles, have lower hydrogen mobility compared to materials containing them, although hydrogen preferably moves along grain boundaries within the material.

[0034] The coating is part of the diaphragm. According to the present invention, the metallic material of the diaphragm includes the coating. The coating is located on the side of the metallic material of the diaphragm that faces the fluid medium.

[0035] According to the present invention, the diaphragm is provided with a coating. The coating serves to reduce the permeability of the diaphragm to atomic or molecular components of the fluid medium, particularly molecular and / or atomic hydrogen. The coating is placed between the metallic material of the diaphragm and the fluid medium, at least in the area that comes into contact with the fluid medium during use. The coating includes oxides, carbides, or nitrides. Examples of oxides, carbides, or nitrides include aluminum oxide, aluminum carbide, aluminum nitride, chromium oxide, chromium nitride, silicon oxide, silicon carbide, silicon nitride, titanium oxide, titanium carbide, titanium nitride, zirconium oxide, or rare earth oxides. The coating prevents direct contact between the metallic material of the diaphragm and the fluid medium. The coating prevents molecular and / or atomic components from the fluid medium from being directly adsorbed onto the metallic material of the diaphragm. The aforementioned oxides, nitrides, and carbides are substantially chemically inert compared to the steel, alloys, and metallic materials mentioned at the beginning. Therefore, coating with a metallic material reduces the chemical reaction or dissociation of its components on the surface of the coated diaphragm. This further improves the corrosion resistance of the diaphragm compared to an uncoated diaphragm.

[0036] The coating is thinner than the thickness of the metal material. Preferably, the coating thickness is a maximum of 10% of the total film thickness. Typical coating thicknesses are 1 μm to 5 μm. Therefore, the stiffness and yield strength of the film are mainly determined by the metal material.

[0037] Typically, the coefficient of thermal expansion of metallic materials is 5.10 in the temperature range of 20°C to 100°C. -6 K -1 ~15.10 6 K -1 Therefore, any mismatch between the metal material and the coating is compensated to some extent by the epitaxial effect. When a coating is applied using an epitaxial process, the epitaxial effect promotes the adhesion of the coating to the metal material.

[0038] Coatings also have a coefficient of thermal expansion. Preferably, the coefficient of thermal expansion of the coating does not differ from that of the metal material by more than 50%. This prevents delamination and cracking of the coating under thermal stress.

[0039] Thermal stress or temperature change occurs when the temperature of at least a portion of the diaphragm increases or decreases by more than 10°C compared to the temperature at any previous point in time. The duration is arbitrary and can be up to several days.

[0040] Advantageously, the diaphragm is equipped with an adhesion promoter layer. The adhesion promoter layer prevents the coating from peeling off the metallic material. Thus, mechanical stress generated during temperature changes is advantageously distributed between the interface between the metallic material and the adhesion promoter layer, and between the adhesion promoter layer and another interface between the coating. This reduces localized mechanical stress and prevents the formation of cracks under mechanical or thermal stress. Advantageously, the adhesion promoter layer is a metal with strong oxygen affinity (e.g., refractory metal, aluminum, or rare earth metal). Refractory metals include titanium, vanadium, chromium, zirconium, niobium, hafnium, tantalum, molybdenum, or tungsten. The purity of the adhesion promoter layer is at least 75% by weight. A purity of at least 75% by weight means that 75% by weight of the adhesion promoter layer consists of metal.

[0041] Preferably, the adhesion promoter layer consists of at least 90% by weight of zirconium or tungsten. The zirconium or tungsten can be easily applied in the form of a layer.

[0042] In embodiments of the present invention, the diaphragm comprises a coating made from a non-stoichiometric oxide, a non-stoichiometric nitride, or a non-stoichiometric carbide.

[0043] Oxides, nitrides, or carbides are non-stoichiometric if the chemical elements are not present in their optimal proportions in each mixture. Typically, for stoichiometric oxides, nitrides, or carbides, the optimal proportion is that of the most stable compound.

[0044] The stoichiometric carbides are, for example, SiC (silicon carbide), Al4C3 (aluminum carbide), or TiC (titanium carbide).

[0045] The non-stoichiometric carbides are the mixture (1-y)M-yMC x (0 < x < x M,C and 0 < y ≤ 1, provided that M = Si and x Si,C = 1, or M = Al and x Al,C = 3 / 4, or M = Ti and x Ti,C = 1). The constant x M,C depends on the element M of the carbide C. x M,C reaches the stoichiometric ratio of each element M combined with carbon C. Other elements can also be used for M. The stoichiometric ratio of the carbides can be obtained from technical literature.

[0046] The stoichiometric nitrides are, for example, AlN (aluminum nitride), CrN (chromium nitride), Si3N4 (silicon nitride), TiN (titanium nitride).

[0047] The non-stoichiometric nitrides are the mixture (1-y)M-yMN x (0 < x < x M,N and 0 < y ≤ 1, provided that M = Al and x Al,N = 1, or M = Cr and x Cr,N = 1, or M = Si and x Si,N = 4 / 3, or M = Ti and x Ti,N = 1). The constant x M,N depends on the element M of the nitride N. x M,N reaches the stoichiometric ratio of each element M combined with nitrogen N. Other elements can also be used for M. The stoichiometric ratio of the nitrides can be obtained from technical literature.

[0048] Stoichiometric oxides include, for example, Al2O3 (aluminum oxide), SiO2 (silicon oxide), TiO2 (titanium oxide), ZrO2 (zirconium oxide), Cr2O3 (chromium oxide), or, in the case of rare earth oxides, Sc2O3, Y2O3, La2O3, CeO2, Pr2O3, Nd2O3, Pm2O3, Sm2O3, EuO, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, and Lu2O3.

[0049] Rare earth elements are Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium).

[0050] Non-stoichiometric oxides are mixtures (1-y)M-yMO x (0 <x<x M,O and 0 <y≦1、ただし、M=Alでx Al、O =1.5, or x with M=Cr. Cr、O =1.5, or x with M=Si. Si、O =2, or x with M=Ti Ti、O =2, or x with M=Zr Zr、O =2, or M = rare earth element x 希土類元素、O =1~2). The constant x M,O This depends on the element M relative to the oxide O. M,O Then, we arrive at the stoichiometric ratio of each element M for each combination of oxygen O. Other elements can also be used for M. The stoichiometric ratios of oxides can be obtained for other elements M in technical literature.

[0051] Coatings made from non-stoichiometric oxides, non-stoichiometric nitrides, or non-stoichiometric carbides are advantageous because the thermal expansion coefficient of the non-stoichiometric oxide, nitride, or carbide can be controlled. Preferably, the thermal expansion coefficient of the coating does not differ from that of the metallic material by more than 50%. This prevents delamination and cracking of the coating under thermal stress. In this embodiment, the adhesion promoter layer can be omitted.

[0052] The word “or” in relation to carbides, nitrides, and oxides should not be understood as an exclusive “or.” Therefore, a coating containing carbides may also contain nitrides. So-called carbonitrides are explicitly disclosed as being included in both carbide-containing and nitride-containing coatings. Examples include mixtures of titanium carbide and titanium nitride (titanium carbonitride), mixtures of zirconium carbide and zirconium nitride (zirconium carbonitride), or mixtures of chromium carbide and chromium nitride (chromium carbonitride). Gold, another material that is substantially chemically inert, has a Vickers hardness of less than 100 HV, while the exemplary oxides, nitrides, and carbides have a Vickers hardness greater than 100 HV. Therefore, the mechanical resistance of the coatings to metallic materials is improved compared to gold coatings known in the prior art.

[0053] Vickers hardness refers to the Vickers hardness under a test force of 10 kilopounds or 10 kgf (kilogram-force), also known as HV10. The Vickers hardness test is described in the standard DIN EN ISO 6507-1:2018 to -4:2018.

[0054] Preferably, the coating contains non-stoichiometric aluminum oxide or non-stoichiometric titanium carbide. Aluminum oxide is known in the industry as a chemically inert material. Also, aluminum oxide is relatively inexpensive compared to rare earth elements or zirconium. Titanium carbide is also widely used in the industry, is cost-effective, and is known as a substantially chemically inert material. The Vickers hardness of another substantially chemically inert material, gold, is less than 100 HV10, but the Vickers hardness of aluminum oxide exceeds 1500 HV10. Therefore, when used as a coating for a metallic material, the mechanical resistance is improved compared to a coating made of gold. The Vickers hardness of titanium carbide exceeds 2500 HV10, and when used as a coating for a metallic material, the mechanical resistance is improved compared to a coating made of gold.

[0055] In a preferred embodiment, the diaphragm comprises a coating of non-stoichiometric aluminum oxide (1 - y)Al - yAlO x (0 < x < 1.5 and 0 < y ≤ 1). The ability to adjust the thermal expansion coefficient of non-stoichiometric aluminum oxide is an advantage. Preferably, the thermal expansion coefficient of the coating differs from that of the metallic material by no more than 50%. This prevents peeling of the coating and formation of cracks under thermal stress. In this embodiment, the adhesion promoter layer can be omitted.

[0056] In one embodiment, the diaphragm comprises a coating of non-stoichiometric carbide (1 - y)M - yMC x (0 < x < x M,C and 0 < y ≤ 1) having a gradient in the coating, or a coating of non-stoichiometric nitride (1 - y)M - yMN x (0 < x < x M,N and 0 < y ≤ 1) having a gradient in the coating, or a coating of non-stoichiometric oxide (1 - y)M - yMO x (0 < x < x M,O and 0 < y ≤ 1) having a gradient in the coating. As already explained, the constants x M,C , x M,N , xM,O This depends on the element M of carbides (C), nitrides (N), and oxides (O), and corresponds to the stoichiometric ratio of each element M associated with carbon (C), nitrogen (N), or oxygen (O). Within the coating, as the distance from the metallic material increases, the ratio y gradually increases. Alternatively, within the coating, as the distance from the metallic material increases, the ratio x gradually increases. However, within the coating, as the distance from the metallic material increases, both ratio x and ratio y may also gradually increase. This has the advantage that by appropriately selecting the ratios x and y, it becomes possible to specifically adapt the coating to the metallic material at the interface between the coating and the metallic material. This adaptation can minimize stress at the interface and / or provide a controlled coefficient of thermal expansion. Creating a gradient within the coating is also advantageous because the physical properties within the coating also change gradually. This prevents the formation of stress or cracks within the coating. On surfaces in contact with a fluid medium, the properties may be adapted to the fluid medium. Therefore, the coating may also be exposed to other substances in the fluid medium besides hydrogen, and by appropriately selecting the ratio x and y, resistance to other substances such as alkaline or acidic gases or liquids can be increased.

[0057] Advantageously, the non-stoichiometric oxide (1-y)M-yMO has a gradient within the coating at the interface between the metallic material and the coating. x , non-stoichiometric nitride (1-y)M-yMN x , or non-stoichiometric carbide (1-y)M-yMC x The thermal expansion coefficient of the coating differs from that of the metal material by less than 50%.

[0058] Particularly preferred is non-stoichiometric aluminum oxide (1-y)Al-yAlO x(0 < x < 1.5 and 0 < y ≤ 1) coating contains an inclination within the coating. As the distance from the metal material increases within the coating, the ratio y gradually increases. Alternatively, as the distance from the metal material increases within the coating, the ratio x gradually increases. However, as the distance from the metal material increases within the coating, both the ratio x and the ratio y can gradually increase. The coefficient of thermal expansion of the coating at the interface between the metal material and the coating does not differ from that of the metal material by more than 50%.

[0059] In both cases where there is and is not an inclination within the coating, non-stoichiometric oxide (1 - y)M - yMO x (0 < x < x M,O and 0 < y ≤ 1) or non-stoichiometric nitride (1 - y)M - yMN x (0 < x < x M,N and 0 < y ≤ 1) or non-stoichiometric carbide (1 - y)M - yMC x (0 < x < x M,CIn one embodiment of a diaphragm having a coating made from 0 < y ≤ 1), the diaphragm comprises at least one other coating. The other coating is disposed on the side opposite the metallic material of the coating. The other coating comprises a stoichiometric oxide, a stoichiometric carbide, or a stoichiometric nitride. Advantageously, the coefficient of thermal expansion of the coating is intermediate between the coefficient of thermal expansion of the metallic material and the coefficient of thermal expansion of the other coating. In this case, the coating functions in part as an adhesion promoter layer, but still serves to reduce the permeability of the diaphragm to molecular hydrogen and / or atomic hydrogen. The other coating further reduces the permeability of the diaphragm to molecular hydrogen and / or atomic hydrogen. The chemical resistance of stoichiometric oxides, stoichiometric nitrides, and stoichiometric carbides is higher than that of non-stoichiometric oxides, non-stoichiometric nitrides, and non-stoichiometric carbides, and is particularly chemically inert. The gradient within the coating is advantageous because the physical properties within the coating change gradually. This prevents the formation of stress or cracks in the coating. At the surface in contact with the other coating, the ratio of x to y can be selected to minimize strain even under thermal stress. The other coating has a particularly chemically inert stoichiometric composition.

[0060] Also, an adhesion promoter layer as described above can be provided between the coating and the metallic material.

[0061] In a special variant of a diaphragm having a coating of a non-stoichiometric oxide, nitride, or carbide having a gradient, at a certain distance from the interface between the coating and the metallic material, the coating transitions to a stoichiometric oxide, nitride, or carbide.

[0062] In another special variant of a diaphragm having a coating of a non-stoichiometric oxide, nitride, or carbide having a gradient, at a certain distance from the interface between the coating and the metallic material, the coating transitions to the respective stoichiometric oxide, nitride, or carbide.

[0063] In a further embodiment, another stoichiometric coating is applied on top of a non-stoichiometric coating. In this case, it is advantageous that the thermal expansion coefficient of the coating lies between that of the metallic material and that of the other coating.

[0064] In a further embodiment, the diaphragm comprises at least one additional coating, the first additional coating being located on the side of the coating facing the fluid medium, and each additional additional coating being located on the side of the other coating before facing the fluid medium. The at least one additional coating, like the aforementioned coating, contains a non-stoichiometric carbide, nitride, or oxide. However, the chemical composition of the additional coatings differs from that of the coating. For example, if the coating is titanium oxide, titanium nitride, or titanium carbide, the additional coatings could be aluminum nitride, aluminum oxide, or aluminum carbide. Thus, adjacent additional coatings also have different chemical compositions. This has the advantage that the additional coatings in contact with the fluid medium can be adapted to the fluid medium and provide, for example, resistance to other substances contained in the fluid medium. The coatings can also be tailored to metallic materials.

[0065] Non-stoichiometric aluminum oxide (1-y)Al-yAlO xIn a particular embodiment of a diaphragm having a coating of (0 < x < 1.5 and 0 < y ≤ 1), the diaphragm comprises at least one other coating. The other coating is disposed on the side opposite to the metallic material of the coating. The additional coating contains stoichiometric aluminum oxide Al2O3. The coefficient of thermal expansion of the coating is between the coefficient of thermal expansion of the metallic material and the coefficient of thermal expansion of the other coating. In this case, the coating functions partly as an adhesion promoter layer, but still serves to reduce the permeability of the diaphragm to molecular hydrogen and / or atomic hydrogen. The other coating further reduces the permeability of the diaphragm to molecular hydrogen and / or atomic hydrogen.

[0066] Non-stoichiometric aluminum oxide (1-y)Al-yAlO with an inclination x In a special variant of a diaphragm having a coating of (0 < x < 1.5 and 0 < y ≤ 1), at a certain distance from the interface between the coating and the metallic material, the coating transitions to stoichiometric Al2O3.

[0067] In one embodiment, the diaphragm comprises an internal coating for reducing the permeability of molecular hydrogen and / or atomic hydrogen. The internal coating is disposed on the side opposite to the fluid medium within the second space of the metallic material of the diaphragm. In this embodiment, the internal coating contains non-stoichiometric oxides, nitrides, or carbides. The same oxides, carbides, or nitrides as already described with respect to the coating are advantageous for this purpose. This means that the deposition can be carried out in the same way as in the case of the coating. The internal coating is particularly advantageous when the second space separated from the fluid medium by the diaphragm by the diaphragm is a closed volume. The closed volume can be, for example, inside the housing of a transducer. The additional internal coating further reduces the diffusion of molecular hydrogen or atomic hydrogen through the diaphragm, and thus reduces the accumulation of hydrogen within the second space. This avoids the aforementioned adverse effects, such as the diaphragm expanding when the pressure transmission medium is disposed within the closed volume.

[0068] In one embodiment, the internal coating may not have the same chemical composition as the coating. Since the coating comes into contact with the fluid medium while the internal coating does not, different coatings can be selected. For example, the internal coating or the coating may be electrically insulating. The coating may also have resistance to other substances that are not required for the internal coating.

[0069] Similar to the coating, an adhesion promoter may optionally be placed between the internal coating and the metal material of the diaphragm.

[0070] The present invention also includes a transducer for determining the pressure of a fluid medium. The transducer comprises a pressure-exposed end facing the fluid medium. The transducer comprises a housing. The transducer comprises a measuring device. The measuring device is located inside the housing. The transducer comprises a diaphragm according to any of the embodiments described above. The second space corresponds to the internal volume of the housing.

[0071] A measuring device for determining the pressure of a fluid medium is, for example, at least one piezoelectric crystal that generates a piezoelectric charge as a function of the pressure acting on a diaphragm. In one embodiment, the piezoelectric crystal is placed in a prestress sleeve that applies prestress to the piezoelectric crystal. Thus, changes in both negative and positive pressure can be detected. Alternatively, the measuring device may also include a capacitance measuring element that detects mechanical deformation in the form of a change in capacitance.

[0072] Alternatively, the measuring device may include a piezoelectric resistance measuring element or strain gauge (also called a strain gauge) that detects mechanical deformation in the form of a change in electrical resistance. Those skilled in the art are aware of other measuring devices used in transducers to determine the pressure of a fluid medium.

[0073] The diaphragm is positioned at the pressure-exposed end of the housing, hermetically isolating the measuring device from the fluid medium. The housing and diaphragm are connected by a material bond. This material bond may be, for example, a welded or soldered connection. A material bond using adhesive is also possible.

[0074] The diaphragm has a first region that comes into contact with the fluid medium during use. The diaphragm also has a second region that does not come into contact with the fluid medium during use. The material bond is located within the second region. Material bonds made as soldered or welded connections are typically prone to more cracks or pores. Even in the case of adhesive material bonds, the adhesive can be damaged by the liquid medium. Therefore, it is preferable to place the material bond within the second region that is not exposed to the fluid medium.

[0075] In the case of a diaphragm with a coating, the coating is distributed over at least the entire first region, but may also extend at least partially over the second region.

[0076] If the concentration of the corrosive component of the fluid medium in the second region is at most 1% of the concentration of the corrosive component in the first region, then the second region is not in contact with the fluid medium in the sense of this specification.

[0077] The first and second regions can be separated from each other, for example, by a sealing element. Depending on the application in which the transducer is used in terms of temperature and pressure range, metal gaskets such as copper gaskets, 1.4404 or 1.4301 steel gaskets, alloy sealing elements, or metal-coated alloy gaskets may be used. Plastic seals are also known for specific temperature and pressure ranges, and include seals made of polytetrafluoroethylene, fluoroelastomers, or nitrile compounds, for example. Other materials can also be used for the sealing element.

[0078] Preferably, this transducer is used to determine the pressure of a fluid medium when the fluid medium is corrosive and conventional transducers cannot be used.

[0079] Particularly preferably, the transducer is used to determine the pressure of a fluid medium containing at least a certain amount of molecular hydrogen and / or atomic hydrogen. Hydrogen is known to cause so-called hydrogen embrittlement in many metallic materials, and when subjected to thermal stress and / or mechanical stress, it leads to hydrogen embrittlement and a decrease in yield strength. The transducer described above significantly mitigates these drawbacks.

[0080] All embodiments of the transducer described are possible as embodiments that include a pressure-transmitting medium located in a second space. However, all embodiments described can also be carried out without placing a pressure-transmitting medium in the second space.

[0081] The present invention also includes a transducer for determining the temperature of a fluid medium. The transducer comprises a pressure-exposed end facing the fluid medium. The transducer comprises a housing. The transducer comprises a measuring device for determining the temperature of the fluid medium. The measuring device is located inside the housing. The transducer comprises a diaphragm according to any of the embodiments described above.

[0082] The present invention will be described in more detail below with reference to the drawings and with examples. [Brief explanation of the drawing]

[0083] [Figure 1] A schematic cross-sectional view of one embodiment of a transducer equipped with one embodiment of the diaphragm according to the present invention is shown, with an optional coating indicated by a dashed line. [Figure 2] A schematic cross-sectional view of one embodiment of the diaphragm is shown. [Figure 3] A schematic cross-sectional view of another embodiment of the diaphragm is shown. [Figure 4]A schematic cross-sectional view of another embodiment of the diaphragm is shown. [Figure 5] Figure 3 is a schematic cross-sectional view of a portion of a transducer equipped with a diaphragm and positioned within a wall. [Figure 6] Figure 2 shows a schematic cross-sectional view of a part of a transducer equipped with a diaphragm and positioned within a wall. [Figure 7] A schematic cross-sectional view of another embodiment of the diaphragm is shown. [Figure 8] A schematic cross-sectional view of another embodiment of the diaphragm is shown. [Figure 9] A schematic cross-sectional view of another embodiment of the diaphragm is shown. [Modes for carrying out the invention]

[0084] Figure 1 shows a schematic cross-sectional view of one embodiment of a transducer 1 equipped with one embodiment of the diaphragm 2 according to the present invention, and an optional coating 4 is shown by a dashed line.

[0085] In Figure 1, which is not drawn to scale, an optional coating 4 of the metal material 3 is shown by a dashed line. Figures 2 to 6 show the following coatings of the diaphragm 2, which differ from those shown in Figure 1.

[0086] In further embodiments shown in Figures 2 to 9, the same or equivalent elements are consistently referred to by their respective reference numerals.

[0087] Figures 2 to 4 show further embodiments of the diaphragm 2. The thickness of the diaphragm 2 and the thickness of the coating 4 are not depicted to exact scale for clarity.

[0088] Figures 5 and 6 show further embodiments of the transducer 1 with a diaphragm 2. The thickness of the diaphragm 2 and the thickness of the coating 4 are not shown to exact scale for clarity.

[0089] The diaphragm 2 in Figures 1 to 6 contains a metallic material 3 and airtightly separates the first space 14 from the second space 15. At least one physical variable can be determined for the fluid medium 13 present in the first space 14. This physical variable is, for example, pressure and / or temperature.

[0090] The surface 6 of the diaphragm 2 faces the fluid medium 13. The diaphragm 2 includes a first region 9 that comes into contact with the fluid medium 13 when the diaphragm 2 is in use. The diaphragm 2 also includes a second region 10 that does not come into contact with the fluid medium 13 when in use, as shown in Figures 1 to 6.

[0091] Advantageously, the diaphragm 2 includes a thin-walled region 21. The thin-walled region 21 preferably has a thickness of less than 500 μm in order to transmit the pressure of the fluid medium 13 from the first space 14 to the second space 15 with as little loss as possible.

[0092] In the embodiments shown in Figures 1 to 6, the diaphragm 2 is provided with a coating 4 for reducing the permeability of molecular or atomic hydrogen, and this coating 4 is positioned between the metal material 3 of the diaphragm 2 and the fluid medium 13, at least in the area that comes into contact with the fluid medium 13 during use. The dashed line representing the coating in Figure 1 indicates that the coating is optional.

[0093] In the embodiments shown in Figures 3 and 5, the diaphragm 2 includes an adhesion promoter layer 5 to prevent the coating 4 from peeling off the metal material 3 of the diaphragm 2.

[0094] In the embodiment shown in Figure 4, the diaphragm 2 is provided with another coating 4' located on the opposite side of the coating 4 from the metal material 3.

[0095] In the embodiment shown in Figure 9, the diaphragm 2 comprises at least one other coating 4', 4'', 4''', ... located on the opposite side of the coating 4 from the metallic material 3. The other coatings 4', 4'', 4''', ... include non-stoichiometric carbides, nitrides, or oxides similar to those of the coating 4 described above.

[0096] In the embodiment shown in Figure 7, the diaphragm 2 includes, for example, an internal coating 22 in addition to the coating 4 on the side of the metal material 3 facing the fluid medium 13. The internal coating 22 is located in a second space 15 of the diaphragm 2 on the side of the metal material 3 opposite to the fluid medium 13. Although not shown in the figure, the internal coating 22 may also be provided in other embodiments.

[0097] In the embodiment shown in Figure 8, the diaphragm 2 comprises a coating 4 and an adhesion promoter layer 5 on the side of the metal material 3 facing the fluid medium 13. This embodiment of the diaphragm 2 further comprises an adhesion promoter layer 5 deposited on the side of the metal material 3 opposite to the fluid medium 13, and this adhesion promoter layer 5 bonds the internal coating 22 to the metal material 3.

[0098] Figures 1 and 5-6 each show an embodiment of a diaphragm 2 introduced into a transducer 1 for determining the pressure of a fluid medium 13. The transducer 1 includes a pressure-exposed end 11 facing the fluid medium 13. The transducer 1 includes a housing 7. A measuring device 16 is located inside the housing 7. Each embodiment of the transducer 1 according to Figure 1, Figure 5, or Figure 6 represents a diaphragm 2 according to the present invention.

[0099] The diaphragm 2 is located at the pressure-exposed end 11 of the transducer 1 and hermetically isolates the measuring device 16 from the fluid medium 13. The housing 7 and the diaphragm 2 are joined to each other by a material-to-material coupling 8. The diaphragm 2 includes a first region 9 that is in contact with the fluid medium 13 when the diaphragm 2 is in use. The diaphragm 2 includes a second region 10 that is not in contact with the fluid medium 13 when in use. When the transducer 1 is in use, the first region 9 and the second region 10 are separated from each other by a sealing element 12. In each of the illustrated embodiments, the material-to-material coupling 8 is located in the second region 10.

[0100] However, it is also conceivable to place the bonds between the materials 8 in regions 9 and 10 that come into contact with the fluid medium 13. In this case, it is advantageous for the bonds between the materials 8 to be completely covered by the coating 4.

[0101] Figures 5 and 6 show transducers 1 used to determine the pressure of the fluid medium 13 inserted into the wall 17. For example, the wall 17 may be the wall 17 of a tank holding the fluid medium 13, a compressor, a heat pump, a refrigerator, a line transporting the fluid medium 13, a combustion chamber of an internal combustion engine, or a gas turbine.

[0102] Of course, the embodiments of the diaphragm 2 or transducer 1 disclosed herein can be combined with each other. Furthermore, embodiments including combinations of the configurations of the embodiments described herein are also expressly encompassed herein. [Explanation of symbols]

[0103] 1 Transducer 2 diaphragms 3 Metal materials 4 Coating 4' Coating 5. Adhesion promoter layer 6 surface 7 Housing 8. Combining materials 9. First Domain 10. Second Domain 11 Pressure-exposed end 12 Seal elements 13 Fluid medium 14. The First Space 15. The Second Space 16 Measuring device 17 Wall 19 Interface 21 Thin wall area 22 Internal coating

Claims

1. A diaphragm (2) for airtightly separating a first space (14) containing a hydrogen-containing fluid medium (13) from a second space (15), The diaphragm (2) includes a metal material (3), The diaphragm (2) is provided with a coating (4) that reduces the permeability of molecular hydrogen and / or atomic hydrogen. The coating (4) is positioned between the metal material (3) of the diaphragm (2) and the fluid medium (13) in the diaphragm (2), at least in the area that comes into contact with the fluid medium (13) during use. The aforementioned coating (4) is (A) A non-stoichiometric carbide mixture containing (1-y)M-yMCx (0 < x < x M, C and 0 < y ≤ 1, where M = Si, x Si, C = 1, or M = Al, x Al, C = 3 / 4, or M = Ti, x Ti, C = 1), or (B) The coating (4) contains a non-stoichiometric nitride mixture (1-y) M-yMN x (0 < x < x M, N and 0 < y ≤ 1, where M = Al, x Al, N = 1, or M = Cr, x Cr, N = 1, or M = Si, x Si, N = 4 / 3, or M = Ti, x Ti, N = 1), or (C) The coating (4) comprises a non-stoichiometric oxide mixture (1-y)M-yMOx (0 < x < x M, O and 0 < y ≤ 1, where M = Al with x Al, O = 1.5, or M = Cr with x Cr, O = 1.5, or M = Si with x Si, O = 2, or M = Ti with x Ti, O = 2, or M = Zr with x Zr, O = 2, or M = rare earth element with x rare earth element, O = 1 to 2), The non-stoichiometric mixture (1-y)M-yMO x or (1-y)M-yMN x or (1-y)M-yMC x is tilted within the coating (4), (i) Within the coating (3), the ratio y gradually increases as the distance from the metal material (3) increases, or (ii) Within the coating (4), the ratio x gradually increases as the distance from the metal material (3) increases, or (iii) Within the coating (4), the ratios x and y gradually increase as the distance from the metal material (3) increases. A diaphragm (2) characterized by the following features.

2. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The coating (4) contains a non-stoichiometric mixture (1-y)M-yMO having a gradient within the coating (4) ｘ or (1-y)M-yMN ｘ Or (1-y)M-yMC ｘ Includes, A diaphragm (2) characterized in that, at a position away from the interface (19) between the coating (4) and the metal material (3), the coating (4) gradually transitions to a stoichiometric mixture of carbides, nitrides, or oxides.

3. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The coating (4) is thinner than the thickness of the metal material (3), or The diaphragm (2) is characterized in that the thickness of the coating (4) does not exceed 10% of the thickness of the diaphragm (2).

4. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The coating (4) has a coefficient of thermal expansion, The aforementioned metal material (3) has a coefficient of thermal expansion, A diaphragm (2) characterized in that, at the interface (19) between the metal material (3) and the coating (4), the thermal expansion coefficient of the coating (4) does not differ from the thermal expansion coefficient of the metal material (3) by more than 50%.

5. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The diaphragm (2) comprises at least one other coating (4', 4'', 4''', ...) The other coatings (4', 4'', 4'''', ...) are arranged on the opposite side of the coating (4) from the metal material (3), The diaphragm (2) is characterized in that the other coatings (4', 4'', 4'''', ...) include stoichiometric oxides, carbides, or nitrides.

6. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 5 from a second space (15), The coating (4) has a coefficient of thermal expansion, The other coatings (4', 4'', 4'''', ...) have a coefficient of thermal expansion, The aforementioned metal material (3) has a coefficient of thermal expansion, The diaphragm (2) is characterized in that the thermal expansion coefficient of the coating (4) is between the thermal expansion coefficient of the metal material (3) and the thermal expansion coefficients of the other coatings (4', 4'', 4'''', ...).

7. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The diaphragm (2) is provided with an adhesion promoter layer (5) that prevents the coating (4) from peeling off the metal material (3) of the diaphragm (2), The adhesion promoter layer is placed between the metal material (3) and the coating (4) of the diaphragm (2). The diaphragm (2) is characterized in that the adhesion promoter layer (5) contains aluminum, a rare earth metal, or a refractory metal.

8. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 7 from a second space (15), The adhesion promoter layer has a purity of at least 75% by weight, or A diaphragm (2) characterized in that the adhesion promoter layer contains at least 90% by weight of zirconium or tungsten.

9. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The diaphragm (2) is characterized in that it comprises an internal coating (22) for reducing the permeability of molecular hydrogen and / or atomic hydrogen, wherein the internal coating (22) is located in the second space (15) of the metal material (3) of the diaphragm (2) on the side opposite to the fluid medium (13).

10. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 9 from a second space (15), The internal coating (22) is a non-stoichiometric carbide mixture (1-y)M-yMC ｘ (0 < x < x Ｍ，Ｃ And 0 < y ≤ 1, where M = Si and x Ｓｉ，Ｃ = 1, or x with M = Al Ａｌ，Ｃ = 3 / 4, or x with M = Ti. Ｔｉ，Ｃ =1) includes or The coating (4) contains a non-stoichiometric nitride mixture (1−y)M−yMN ｘ (0 < x < x Ｍ，Ｎ and 0 < y ≤ 1, provided that M = Al and x Ａｌ，Ｎ = 1, or M = Cr and x Ｃｒ，Ｎ = 1, or M = Si and x Ｓｉ，Ｎ = 4 / 3, or M = Ti and x Ｔｉ，Ｎ = 1), or The coating (4) is a non-stoichiometric oxide mixture (1-y)M-yMO ｘ (0 < x < x Ｍ，Ｏ And 0 < y ≤ 1, where M = Al and x Ａｌ、Ｏ = 1.5, or x with M = Cr. Ｃｒ、Ｏ = 1.5, or x with M = Si. Ｓｉ、Ｏ = 2, or x with M = Ti. Ｔｉ、Ｏ = 2, or x with M = Zr Ｚｒ、Ｏ = 2, or M = rare earth element x 希土類元素、Ｏ A diaphragm (2) characterized by including (1) to (2).

11. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The diaphragm (4) is characterized in that it has a thickness of less than 500 μm in at least part of its structure, wherein the diaphragm (2) is also characterized in that it has a thickness of less than 500 μm in at least part of its structure.

12. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The diaphragm (2) is characterized in that the metal material (3) is martensite, bainite, needle ferrite, Widmanstättenferrite, or a mixture thereof.

13. A transducer (1) for measuring the pressure of a hydrogen-containing fluid medium (13), The transducer (1) has a pressure-exposed end (11) facing the fluid medium (13), The transducer (1) comprises a housing (7), The transducer (1) is equipped with a measuring device (16), The transducer (1) is characterized by comprising a diaphragm (2) as described in any one of claims 1 to 12.

14. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The diaphragm (2) is characterized in that the coating (4) contains aluminum oxide, aluminum carbide, aluminum nitride, chromium oxide, chromium nitride, silicon oxide, silicon carbide, silicon nitride, titanium oxide, titanium carbide, titanium nitride, zirconium oxide, or rare earth oxides.

15. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 1 from a second space (15), The aforementioned coating (4) is Non-stoichiometric titanium carbide (1-y)Ti-yTiC ｘ (0 < x < 1 and 0 < y ≤ 1), or Non-stoichiometric aluminum oxide (1-y)Al-yAlO ｘ (0 < x ≤ 1.5 and 0 ≤ y ≤ 1) A diaphragm (2) characterized by including the following.

16. A diaphragm (2) for airtightly separating a first space (14) containing the hydrogen-containing fluid medium (13) described in claim 7 from a second space (15), The diaphragm (2) is characterized in that the adhesion promoter layer (5) contains titanium, vanadium, chromium, zirconium, niobium, hafnium, tantalum, molybdenum, or tungsten.

17. A diaphragm (2) for airtightly separating a first space (14) containing a hydrogen-containing fluid medium (13) as described in claim 10 from a second space (15), The aforementioned internal coating (22) is Non-stoichiometric titanium carbide (1-y)Ti-yTiC ｘ (0 < x < 1 and 0 < y ≤ 1), or Non-stoichiometric aluminum oxide (1-y)Al-yAlO ｘ (0 < x ≤ 1.5 and 0 ≤ y ≤ 1) A diaphragm (2) characterized by including the following.

18. A diaphragm (2) for airtightly separating a first space (14) containing a hydrogen-containing fluid medium (13) as described in claim 12 from a second space (15), The diaphragm (2) is characterized in that the metal material (3) is a fine-grained steel having a martensite structure with partially coherent or non-coherent precipitates.

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