DIAPHRAGM FOR USE WITH HYDROGEN-CONTAINING FLUID MEDIA AND TRANSDUCER COMPRISING SUCH A DIAPHRAGM

Abstract

A diaphragm for hermetically separating a first space accommodating a hydrogen-containing fluid medium from a second space. The diaphragm includes a metallic material and a coating that has properties effecting a reduction of the permeability for molecular and/or atomic hydrogen. The coating is arranged between the metallic material of the diaphragm and the fluid medium at least in an area that shields the metallic material from coming into contact with the fluid medium when the diaphragm is in use. The coating includes at least one non-stoichiometric oxide, carbide or nitride.

Claims

1. A diaphragm for hermetically separating a first space from a second space that is configured to contain a fluid medium, which includes hydrogen, the diaphragm comprising: a metallic material disposed to face towards the second space; a coating disposed between the metallic material and the second space, wherein the coating is configured for reducing the permeability for molecular and/or atomic hydrogen; wherein the coating includes at least one non-stoichiometric oxide, carbide or nitride comprising 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.

2. The diaphragm according to claim 1, wherein the coating comprises a non-stoichiometric carbide mixture (1-y)M-yMC.sub.x (with 0<x<x.sub.M,C and 0<y<=1, where M=Si with x.sub.Si,C=1, or M=Al with x.sub.Al,C=3/4, or M=Ti with x.sub.Ti,C=1); or wherein the coating comprises a non-stoichiometric nitride mixture (1-y)M-yMN.sub.x (with 0<x<x.sub.M,N and 0<y<=1, where M=Al with x.sub.Al,N=1, or M=Cr with x.sub.Cr,N=1, or M=Si with x.sub.Si,N=4/3, or M=Ti with x.sub.Ti,N=1); or wherein the coating (4) comprises a non-stoichiometric oxide mixture (1-y)M-yMO.sub.x (with 0<x<x.sub.M,O and 0<y<=1; where M=Al with x.sub.Al,O=1.5, or M=Cr with x.sub.Cr,O=1.5, or M=Si with x.sub.Si,O=2, or M=Ti with x.sub.Ti,O=2, or M=Zr with x.sub.Zr,O=2, or M=rare earths with x.sub.rare earths,O=1 to 2).

3. The diaphragm according to claim 2, wherein the coating comprises a non-stoichiometric mixture (1-y)M-yMO.sub.x or (1-y)M-yMN.sub.x or (1-y)M-yMC.sub.x with a gradient within the coating such that within the coating the proportion y gradually increases with increasing distance from the metallic material; or wherein the coating comprises a non-stoichiometric mixture (1-y)M-yMO.sub.x or (1-y)M-yMN.sub.x or (1-y)M-yMC.sub.x with a gradient within the coating such that within the coating the proportion x gradually increases with increasing distance from the metallic material; or wherein the coating comprises a non-stoichiometric mixture (1-y)M-yMO.sub.x or (1-y)M-yMN.sub.x or (1-y)M-yMC.sub.x with a gradient within the coating such that within the coating the proportion x and the proportion y gradually increase with increasing distance from the metallic material.

4. The diaphragm according to claim 3, wherein the coating comprises a non-stoichiometric mixture (1-y)M-yMO.sub.x or (1-y)M-yMN.sub.x or (1-y)M-yMC.sub.x with a gradient within the coating such that there is a gradual transition of the coating into a stoichiometric mixture of a carbide, nitride or oxide at a distance from the interface between the coating and the metallic material.

5. The diaphragm according to claim 1, wherein the coating is thinner than the thickness of the metallic material or wherein the thickness of the coating does not exceed 10% of the thickness of the diaphragm.

6. The diaphragm according to claim 1, wherein the coating has a coefficient of thermal expansion; wherein the metallic material has a coefficient of thermal expansion; wherein at an interface between the metallic material and the coating the coefficient of thermal expansion of the coating does not differ by more than 50% from the coefficient of thermal expansion of the metallic material.

7. The diaphragm according to claim 1, further comprising at least one further coating; wherein the at least one further coating is arranged on a side of the coating that faces away from the metallic material; and wherein the at least one further coating comprises stoichiometric oxide, carbide or nitride.

8. The diaphragm according to claim 7; wherein the coating has a coefficient of thermal expansion; in that the at least one further coating has a coefficient of thermal expansion; wherein the metallic material has a coefficient of thermal expansion; and wherein the coefficient of thermal expansion of the coating has a value between that of the coefficient of thermal expansion of the metallic material and the coefficient of thermal expansion of the at least one further coating.

9. The diaphragm according to claim 1, further comprising an adhesion promoter layer that prevents delamination of the coating from the metallic material of the diaphragm; wherein the adhesion promoter layer is arranged between the metallic material of the diaphragm and the coating; and wherein the adhesion promoter layer comprises aluminum or rare earth metals or a refractory metal including titanium, vanadium, chromium, zirconium, niobium, hafnium, tantalum, molybdenum, or tungsten.

10. The diaphragm according to claim 18, wherein the adhesion promoter layer has a purity of at least 75% by weight; or wherein the adhesion promoter layer comprises at least 90% by weight of zirconium or tungsten.

11. The diaphragm according to claim 1, further comprising an internal coating for reducing the permeability for molecular and/or atomic hydrogen, which internal coating is arranged in the second space on a side of the metallic material of the diaphragm that is disposed to face away from the fluid medium.

12. The diaphragm according to claim 11, wherein the internal coating comprises a non-stoichiometric carbide mixture (1-y)M-yMC.sub.x (with 0<x<x.sub.M,C and 0<y<=1, where M=Si with x.sub.Si,C=1, or M=Al with x.sub.Al,C=3/4, or M=Ti with x.sub.Ti,C=1); or wherein the coating comprises a non-stoichiometric nitride mixture (1-y)M-yMN.sub.x (with 0<x<x.sub.M,N and 0<y<=1, where M=Al with x.sub.Al,N=1, or M=Cr with x.sub.Cr,N=1, or M=Si with x.sub.Si,N=4/3, or M=Ti with x.sub.Ti,N=1); or wherein the coating comprises a non-stoichiometric oxide mixture (1-y)M-yMO.sub.x (with 0<x<x.sub.M,O and 0<y<=1; where M=Al with x.sub.Al,O=1.5, or M=Cr with x.sub.Cr,O=1.5, or M=Si with x.sub.Si,O=2, or M=Ti with x.sub.Ti,O=2, or M=Zr with x.sub.Zr,O=.sup.2, or M=rare earths with x.sub.rare earths,O=1 to 2).

13. The diaphragm according to claim 1, wherein at least a portion of the diaphragm is defined by a thickness of less than 500 m.

14. The diaphragm according to claim 1, wherein the metallic material is a fine-grained steel having a structure of martensite, bainite, needle ferrite, Widmannsttten ferrite or a mixture of these structures.

15. A transducer (1) for measuring a pressure of a hydrogen-containing fluid medium disposed within a space, the transducer comprising: a pressure-exposed end that is disposable to face the fluid medium that is to be measured when the transducer is in use; a housing; a measuring arrangement disposed in the housing and including a sensor configured to generate a signal proportionate to a pressure detected by the sensor; and a diaphragm that includes: a metallic material, a coating disposed between the metallic material and the space in which the fluid medium is disposed, wherein the coating is configured for reducing the permeability for molecular and/or atomic hydrogen, wherein the coating includes at least one non-stoichiometric oxide, carbide or nitride comprising 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.

16. The diaphragm according to claim 2, wherein the coating comprises non-stoichiometric titanium carbide (1-y)Ti-yTiC.sub.x (with 0<x<1 and 0<y<=1).

17. The diaphragm according to claim 2, wherein the coating comprises non-stoichiometric aluminum oxide (1-y)Al-yAlO.sub.x (with 0<x<=1.5 and 0<=y<=1).

18. The diaphragm according to claim 1, further comprising an adhesion promoter layer that prevents delamination of the coating from the metallic material of the diaphragm; wherein the adhesion promoter layer is arranged between the metallic material of the diaphragm and the coating; and wherein the adhesion promoter layer comprises aluminum or rare earth metals or a refractory metal including zirconium or tungsten.

19. The diaphragm according to claim 11, wherein the internal coating comprises a non-stoichiometric carbide mixture of non-stoichiometric titanium carbide (1-y)Ti-yTiC.sub.x (with 0<x<1 and 0<y<=1).

20. The diaphragm according to claim 11, wherein the coating comprises non-stoichiometric aluminum oxide (1-y)Al-yAlO.sub.x (with 0<x<=1.5 and 0<=y<=1).

21. The diaphragm according to claim 14, wherein the metallic material includes a fine-grained steel having a structure of martensite with partially coherent or incoherent precipitates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0094] In the following, the invention will be explained in more detail by way of example with reference to the Figures in which:

[0095] FIG. 1 shows a schematic sectional view of an embodiment of a transducer comprising an embodiment of a diaphragm according to the invention where an optional coating is shown by the dash-dotted line;

[0096] FIG. 2 shows a schematic sectional view of an embodiment of a diaphragm;

[0097] FIG. 3 shows a schematic sectional view of a further embodiment of a diaphragm;

[0098] FIG. 4 shows a schematic sectional view of a further embodiment of a diaphragm;

[0099] FIG. 5 shows a schematic sectional view of a portion of a transducer comprising a diaphragm according to FIG. 3 and arranged in a wall;

[0100] FIG. 6 shows a schematic sectional view of a portion of a transducer comprising a diaphragm according to FIG. 2 and arranged in a wall;

[0101] FIG. 7 shows a schematic sectional view of a further embodiment of a diaphragm;

[0102] FIG. 8 shows a schematic sectional view of a further embodiment of a diaphragm; and

[0103] FIG. 9 shows a schematic sectional view of a further embodiment of a diaphragm.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

[0104] FIG. 1 shows a schematic sectional view of an embodiment of a transducer 1 with an embodiment of a diaphragm 2 according to the invention wherein an optional coating 4 is shown by the dash-dotted line.

[0105] In the representation of FIG. 1, which is not drawn to scale, an optional coating 4 of the metallic material 3 is shown as a dash-dotted line. FIGS. 2 to 6 show the coating of a diaphragm 2 in the following differing from the representation shown in FIG. 1.

[0106] In the further embodiments of FIGS. 2 to 9 the reference numerals are used consistently for the same or equivalent elements.

[0107] FIGS. 2 to 4 show further embodiments of a diaphragm 2. The thickness of the diaphragm 2 and the thickness of the coating 4 are not drawn in correct scale for clarity.

[0108] FIGS. 5 to 6 show further embodiments of a transducer 1 comprising a diaphragm 2. The thickness of the diaphragm 2 and the thickness of the coating 4 are not drawn in correct scale for clarity.

[0109] The diaphragm 2 of FIGS. 1 to 6 comprises a metallic material 3 and hermetically separates a first space 14 from a second space 15. For a fluid medium 13 present in the first space 14 at least one physical variable can be determined. A physical variable is a pressure and/or a temperature, for example.

[0110] The thickness of the diaphragm 2, the metallic material 3 and coating 4 are measured in the direction that is parallel to the plane of the figure moving from the first space 14 to the second space 15.

[0111] The surface 6 of the diaphragm 2 faces towards the fluid medium 13 when the diaphragm 2 is deployed in its intended use. The diaphragm 2 comprises a first region 9 that is in contact with the fluid medium 13 when the diaphragm 2 is in use as schematically shown in FIGS. 1, 5, 6 and 7 for example. The diaphragm 2 comprises a second region 10 that is not in contact with the fluid medium 13 when in use, as shown in FIGS. 1, 5 and 6 for example.

[0112] Advantageously, the diaphragm 2 comprises a thin-walled region 21. The thin-walled region 21 preferably has a thickness of less than 500 m to transmit a pressure of a fluid medium 13 from the first space 14 to a second space 15 with as little loss as possible.

[0113] In the embodiments shown in FIGS. 1 to 6, the diaphragm 2 comprises the coating 4 for reducing the permeability for molecular or atomic hydrogen, said coating 4 being arranged between the metallic material 3 of the diaphragm 2 and the fluid medium 13 at least in the area which is in contact with the fluid medium 13 during use. The coating 4 comprises a non-stoichiometric carbide, nitride or oxide described above. The dash-dotted line representing the coating in FIG. 1 indicates that the coating is optional.

[0114] In the embodiments shown in FIGS. 3 and 5, the diaphragm 2 comprises an adhesion promoter layer 5 for preventing delamination of the coating 4 from the metallic material 3 of the diaphragm 2.

[0115] In the embodiment according to FIG. 4, the diaphragm 2 comprises a further coating 4 arranged on the side of the coating 4 that faces away from the metallic material 3.

[0116] In the embodiment according to FIG. 9, the diaphragm 2 comprises at least one further coating 4, 4, 4, . . . arranged on the side of the coating 4 that faces away from the metallic material 3. The further coating 4, 4, 4, . . . comprises a non-stoichiometric carbide, nitride or oxide similar to the coating 4 described above.

[0117] In the embodiment according to FIG. 7, the diaphragm 2 comprises, for example, an internal coating 22 in addition to a coating 4 on the side of the metallic material 3 that faces towards the fluid medium 13. The internal coating 22 is arranged to face the second space 15 on the side of the metallic material 3 of the diaphragm 2 that faces away from the fluid medium 13 when in use. Although not represented in the Figures, an internal coating 22 may also be provided in other embodiments.

[0118] In the embodiment according to FIG. 8, the diaphragm 2 comprises a coating 4 and an adhesion promoter layer 5 on the side of the metallic material 3 of the diaphragm 2 that faces towards the fluid medium 13. This embodiment of the diaphragm 2 additionally comprises an adhesion promoter layer 5 deposited on the side of the metallic material 3 that faces away from the fluid medium 13, which adhesion promoter layer 5 joins an internal coating 22 to the metallic material 3.

[0119] FIG. 1 and FIGS. 5 to 6 each show an embodiment of a diaphragm 2 introduced in a transducer 1 for determining a pressure of a fluid medium 13. The transducer 1 comprises a pressure-exposed end 11 facing towards the fluid medium 13 when in use. The transducer 1 comprises a housing 7. A measuring arrangement 16 is arranged in the housing 7. Each embodiment of a transducer 1 according to FIG. 1, 5 or 6 represents a diaphragm 2 according to the invention.

[0120] The diaphragm 2 is arranged at the pressure-exposed end 11 of the transducer 1 and hermetically separates the measuring arrangement 16 from the fluid medium 13. The housing 7 and diaphragm 2 are joined to each other by a bond between materials 8. The diaphragm 2 comprises a first region 9 that is in contact with the fluid medium 13 when the diaphragm 2 is in use. The diaphragm 2 comprises a second region 10 that is not in contact with the fluid medium 13 when in use. The first and second regions 9, 10 are separated from each other by a sealing element 12 when the transducer 1 is in use. In each of the embodiments shown, the bond between materials 8 is arranged in the second region 10.

[0121] It is also conceivable, however, to arrange the bond between materials 8 in a region 9, 10 that is in contact with the fluid medium 13. In this case, the bond between materials 8 is advantageously completely covered by the coating 4.

[0122] FIGS. 5 and 6 show the transducer 1 for use in determining a pressure of a fluid medium 13 inserted into a wall 17. For example, the wall 17 may be a wall 17 of a tank for holding a fluid medium 13, of a compressor, a heat pump, a refrigeration machine, a line for transporting a fluid medium 13, a combustion chamber of an internal combustion engine or a gas turbine.

[0123] It is, of course, possible to combine features of the embodiments of the diaphragm 2 or of the transducer 1 disclosed in this document with each other. Furthermore, embodiments comprising a combination of features of the embodiments described herein are explicitly encompassed by this document.

LIST OF REFERENCE NUMERALS

[0124] 1 transducer [0125] 2 diaphragm [0126] 3 metallic material [0127] 4 coating [0128] 4 coating [0129] 5 adhesion promoter layer [0130] 6 surface [0131] 7 housing [0132] 8 bond of materials [0133] 9 first region [0134] 10 second region [0135] 11 pressure-exposed end [0136] 12 sealing element [0137] 13 fluid medium [0138] 14 first space [0139] 15 second space [0140] 16 measuring arrangement [0141] 17 wall [0142] 19 interface [0143] 21 thin-walled region [0144] 22 internal coating