JOINING TWO COMPONENTS OF A FIELD DEVICE FOR PROCESSING AND AUTOMATION TECHNOLOGY

Abstract

A field device for processing and automation technology includes a first and a second component that can each be mechanically connected at a joining surface by means of a joining point. Two metal surface layers are each applied at least to the joining surface of the first component and the joining surface of the second component. The metal of the surface layers is different from the metal of the first and/or the metal of the second component. A joining material is applied between the respective joining surfaces of the two components, wherein the joining material includes particles at least partially consisting of a metal that corresponds with the metal of the surface layers The joining of the two components occurs at a joining temperature below 300° C.

Claims

1-15. (canceled)

16. A field device for process automation, comprising: a first metal component and a second metal component, wherein the first component and the second component are mechanically connected to one another at a joining surface via a joining point, wherein the connecting of the first component with the second component includes: coating a joining surface of the first component and a joining surface of the second component with a metallic surface layer, wherein the metal of the surface layers is different from the metal of the first and/or the metal of the second component; applying a joining material between the respective joining surfaces of the two components, wherein the joining material includes particles at least partially consisting of a metal, wherein the metal of the joining material corresponds with the metal of the surface layers; and joining the first and second components at their respective joining surface by heating at a joining temperature below 300° C.

17. The field device according to claim 16, wherein the field device relates to a pressure transducer, wherein the first component is a metallic support and the second component is a metallic membrane arranged on the metallic support so as to enclose a pressure chamber.

18. The field device according to claim 16, wherein the particles have silver or copper or gold as metal.

19. The field device according to claim 16, wherein the particles comprise silver nitrate, silver acetate, silver carbonate, or silver oxide.

20. The field device according to claim 16, wherein the particles have a silver, copper, or gold alloy.

21. The field device according to claim 16, wherein the joining material includes at least a liquid and/or a solvent and/or an additive agent in addition to the particles at least partially consisting of metal.

22. The field device according to at least claim 16, wherein the diameter of the particles at least partially consisting of metal is less than 1 μm.

23. The field device according to claim 16, wherein the first component is manufactured from stainless steel, duplex steel and/or super duplex steel, and/or unalloyed steel and/or Monel and/or a copper alloy, and wherein the second component is manufactured from stainless steel, duplex steel and/or super duplex steel, and/or Hastelloy and/or tantalum and/or Monel and/or titanium and/or zirconium and/or a copper alloys and/or a silver alloys and/or a gold alloys.

24. The field device according to claim 16, wherein the metallic surface layer is applied to the two components by galvanic processes or sputtering.

25. The field device according to claim 24, wherein the metallic surface layer has a thickness of 2 to 30 μm.

26. The field device according to claim 16, wherein an additional adhesive layer is applied between the first component and its surface layer and between the second component and its surface layer and respectively connects the surface layer to the first and the second component.

27. The field device according to claim 26, wherein adhesive gold or copper or chromium is used as the adhesive layer.

28. The field device according to claim 16, wherein the joining temperature is in the range of 250° C. to 280° C.

29. A method for producing a device consisting of at least one first and one second component, wherein the first and second components are components of a field device for processing and automation technology, which can each be mechanically connected at a joining surface via a joining point, the method comprising: coating in each case at least the joining surface of the first and of the second component with a metallic surface layer, wherein the metal of the surface layers is different from the metal of the first and/or the metal of the second component; applying a joining material between the respective joining surfaces of the two components, wherein the joining material includes at least particles at least partially consisting of a metal, wherein the metal of the joining material corresponds with the metal of the surface layers, and joining the first and second components at their respective joining surface by heating at a joining temperature below 300° C.

30. The method according to claim 29, further comprising: coating the joining surface of the first and second components in each case with an adhesive layer that is respectively arranged between the surface layer and the first and second components.

Description

[0044] The solution according to the invention is explained in greater detail with reference to the following FIGS. 1-2. The following is shown:

[0045] FIG. 1 a schematic representation of a pressure measuring device.

[0046] FIG. 2 a schematic representation of a pressure transducer according to the invention.

[0047] The present invention is applicable to a plurality of different field devices. Without limiting generality, however, the following description relates to a pressure measuring device, as schematically illustrated in FIG. 1, for the sake of simplicity. Corresponding pressure measuring devices are produced and marketed by the applicant under the names “Cerabar,” “Ceraphant,” and “Deltabar,” for example. The considerations can be applied analogously to other field devices which have at least one component with a high sensitivity to the process variable and/or to parameters that are decisive for the determination of the process variable.

[0048] FIG. 1 shows a schematic representation of a corresponding pressure measuring device 11. In this case, the membrane 3 faces the process and adjoins the support 2. The pressure sensor 12 is located at a certain distance from the membrane 3 and the support 2. The pressure acting on the membrane 3 is transmitted to the pressure sensor 12 by means of a liquid (not shown).

[0049] FIG. 2 shows a possible embodiment of the device according to the invention on the basis of a pressure transducer 1. The membrane 3 and the support 2 are arranged opposite one another, with joining surfaces 4, 5 facing one another, at which the membrane 3 and support 2 can be connected. A pressure chamber 9 is arranged between the membrane 3 and the support 2 and is adjoined by a bore extending through the support 2. The support 2 can be manufactured from stainless steel, especially, duplex steel and/or super duplex steel, and/or unalloyed steel and/or Monel and/or a copper alloy, and the membrane 3 can be manufactured from stainless steel, especially, duplex steel and/or super duplex steel, and/or Hastelloy and/or tantalum and/or Monel and/or titanium and/or zirconium and/or a copper alloys and/or a silver alloys and/or a gold alloys.

[0050] An adhesive layer 10 is applied to the respective joining surface of membrane and support 4, 5. The adhesive layer 10 can consist of adhesive gold, copper, chromium or further substances. In each case, a surface layer 7 is applied at least to the joining surface of the membrane 5 and the joining surface of the support 4, for example by means of a galvanic process or by means of sputtering, wherein the metal of the surface layers 7 is different from the metal of the support 2 and/or the metal of the membrane 3. One possible combination would be the coating of membrane 3 and support 2, both of which are made of stainless steel, with a layer of silver. Advantageously, the metallic surface layer 7 has a thickness of 2 to 30 μm.

[0051] A joining material 8 is applied between the respective surface layers 7 in the region of the joining surface of membrane and support 4, 5 and comprises at least particles at least partially consisting of a metal. The metal of the joining material 8 corresponds with the metal of the surface layers 7. The particles have, for example, gold, copper, or silver, as well as alloys of these metals, or also silver nitrate, silver acetate, silver carbonate, or silver oxide. In addition to the particles, the joining material 8 also consists of at least a liquid and/or a solvent and/or an additive agent. The diameter of the particles is less than 1 μm, with other possibilities not being ruled out. The joining takes place at joining temperatures below 300° C., for example at 250-280° C.

[0052] A device 1 of this kind, such as a pressure transducer, is produced by means of a method according to the invention by first coating the first and second components 2, 3 on at least their respective joining surface 4, 5 with a surface layer 7. The surface layer 7 has a metal which is different from the metal of the first and second components 2, 3. Subsequently, the joining material 8 is applied to the respective joining surfaces of the two components 4, 5. The joining material 8 comprises at least particles at least partially consisting of metal, wherein the metal of the joining material 8 corresponds with the metal of the surface layers 7 so that good adhesion between the joining material 8 and the surface layer 7 is obtained. In a further step, the two components 2, 3 are joined at their respective joining surfaces 4, 5 at a joining temperature of below 300° C. Optionally, before the application of the surface layer 7, the joining surfaces of the first and the second component 4, 5 can first be coated with an adhesive layer 10, which connects the surface layer 7 to the first and the second component 2, 3.

LIST OF REFERENCE SIGNS

[0053] 1 Device or pressure transducer

[0054] 2 First component or support

[0055] 3 Second component or membrane

[0056] 4 Joining surface of the first component or of the support

[0057] 5 Joining surface of the second component or of the membrane

[0058] 6 Joining point

[0059] 7 Surface layer

[0060] 8 Joining material

[0061] 9 Pressure chamber

[0062] 10 Adhesive layer

[0063] 11 Pressure measuring device

[0064] 12 Pressure sensor