Connection Elements
The joining element with localized heating addresses the energy and size limitations of conventional diffusion bonding, enabling efficient bonding of larger components and harsh environments with reduced energy consumption.
Patent Information
- Application Number
- JP2025517546
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-26
- Filing Date
- 2023-09-25
- Publication Date
- 2025-09-11
AI Technical Summary
Existing diffusion bonding methods require large furnaces and extended heating times, limiting their application to small assemblies and consuming significant energy, making them unsuitable for larger components or harsh environments.
A joining element with a localized heating structure and resistive heating element is used to diffusion bond components, allowing for localized heating and reducing energy consumption, suitable for larger assemblies and harsh environments.
Enables diffusion bonding of larger components and harsh environments with reduced energy consumption and size limitations, forming permanent seals in ultra-high vacuum conditions.
Smart Images
Figure 2025530499000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a joining element and joining method for joining components. [Background technology]
[0002] In many industries, a reliable seal between components, such as between the flanges of joined pipe sections, is important. In some cases, a gasket or spring-loaded metal seal may be sufficient to provide an airtight seal between components when compressed. For high temperature and pressure applications, or when adequate compression cannot be maintained, it may be necessary to permanently join the components, for example, by fusion welding or brazing. This is not always possible and may result in damage to the components being joined.
[0003] Diffusion bonding is a solid-state technique used to permanently join components. It operates on the principle of solid-state diffusion, where atoms at two solid (e.g., metal) surfaces disperse themselves over time. Diffusion bonding can be used to join similar or dissimilar materials, including a wide range of metals, alloys, and ceramic materials, including aluminum alloys, titanium alloys, steel, copper alloys, silicon carbide (SiC), silicon nitride (Si3N4), and metal matrix composites. Diffusion bonding is typically performed by subjecting the components to be joined in a vacuum or inert gas environment to high pressure and temperature (but below the lowest melting point of each component or any interlayer).
[0004] Figure 1 shows a schematic diagram of a system 1 for diffusion bonding. Two parts 2 are pressed together by a hydraulic press 3 and heated by a heater 4 in a vacuum furnace 5 to produce a bond between the parts 2. Diffusion bonding is used in a wide range of industries, but is typically only used to produce relatively small assemblies of components due to the need to place the components in a suitable furnace 5 and heat them for extended periods of time. Summary of the Invention [Means for solving the problem]
[0005] In one aspect, the present invention provides a method of joining two components, the method comprising: placing a joining element comprising a joining structure and a heating element between the two components; compressing the joining element between the two components; and heating the joining structure with the heating element to diffusion bond the joining structure to each of the two components to form a bond therebetween. Advantageously, by placing the joining structure and the heating element between the two components, diffusion bonding can be achieved by applying only localized heating to the joining structure, rather than placing the assembly in a heating furnace. This may allow diffusion bonding to be used for larger assemblies and / or consume less heating energy than conventional methods. For example, diffusion bonding can be used to form permanent seals between parts of a vacuum chamber or large tubing sections.
[0006] At least the outer surface of the joining structure comprises a material suitable for diffusion bonding to each of the two components, such as metal or, in some embodiments, aluminum.
[0007] In another aspect, the present invention provides a joining element for joining (e.g., suitable for diffusion bonding) two components, the joining element comprising a joining structure having an outer metal surface and a heating element (e.g., a resistive heating element) proximate to the joining structure (e.g., such that the heating element provides localized heating to the joining structure in use), the joining element configured to be located between the two components, and the heating element configured to heat the joining structure sufficiently in use to join the outer metal surface of the joining structure to each of the two components.
[0008] The interface element can include a spring-loaded metal seal, the heating element can include a helical spring of the spring-loaded metal seal, and the interface element can include a sealing jacket around at least a portion of the helical spring. In this embodiment, a seal can be formed between two components by placing the interface element between the components, and the seal can then be made permanent by internally heating the interface element to bond it to each of the components. In a typical spring-loaded metal seal, both the spring and the outer jacket form a closed loop. In this embodiment, the spring does not form a closed loop (e.g., there is at least one separation) so that a voltage can be applied across it.
[0009] In another aspect, the present invention provides a joining element for joining two components, the joining element comprising: a joining structure positioned between the two components; and a heating element connected to the joining structure and configured to heat the joining structure sufficiently to join the joining structure to each of the two components. Thus, the joining structure joins the two components together. The joining structure may be a sealing structure (e.g., comprising a closed loop) that also provides a seal between the two components when used for joining. The joining or sealing structure may comprise a metal (e.g., aluminum) surface (e.g., shell, jacket, foil, etc.) that at least partially surrounds the heating element. Thus, the joining or sealing structure may be configured to diffusion bond (e.g., aluminum diffusion bond) its metal surface to the surfaces of each of the two components when in use.
[0010] In another aspect, the present invention provides a method of joining two components, the method comprising: providing a joining element comprising a joining structure and a heating element, the heating element being connected to the joining structure; positioning the joining element between the two components; applying pressure to the joining element through the two components; and heating the joining structure with the heating element to join the joining structure to each of the two components. The joining structure can be a sealing structure (e.g., comprising a closed loop) such that joining the joining structure to each of the two components includes providing a seal therebetween. [Brief explanation of the drawings]
[0011] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. [Figure 1] 1 shows a schematic diagram of a system for diffusion bonding. [Figure 2] 1 shows a schematic diagram of a joining element. [Figure 3] 1 shows a schematic diagram of two components joined by a joining element. [Figure 4] 1 shows a schematic cross-sectional view of a joining element. [Figure 5] 1 shows a flowchart of a joining method. DETAILED DESCRIPTION OF THE INVENTION
[0012] The embodiments described herein provide a joining element for joining two components. The joining element includes a joining structure located between the two components and a heating element adjacent the joining structure and configured to locally heat the joining structure sufficiently to diffusion bond the joining structure to each of the two components, thereby connecting and bonding the two components together. Advantageously, when formed as a closed loop, for example, the joining structure can also be used as a sealing structure to provide a seal between the two components when used for joining. While the following description focuses on embodiments of the invention in which the joining element includes a sealing structure, it will be recognized that the provision of a localized heating element is generally advantageous for joining structures suitable for diffusion bonding.
[0013] The sealing structure may comprise a metal or any other suitable material capable of forming a diffusion bond with the components being joined. For example, aluminum can form a diffusion bond with a wide range of metals, ceramics, glasses, and crystalline solids. Thus, the sealing structure may be configured for aluminum diffusion bonding, forming a bonding interlayer or bonding structure between the two components. The choice of material for the sealing structure may depend on the materials of the opposing surfaces of the components being joined. These surfaces may comprise any suitable material, including metals (e.g., copper), ceramics, glasses, or crystalline solids. The components (and / or their opposing surfaces) may comprise the same or different materials. For example, the joining element may be configured to provide a seal between a metal component and a ceramic component.
[0014] The sealing structure may comprise a metal jacket, foil, or shell that at least partially surrounds the heating element, i.e., the heating element is an internal heating element of the sealing structure. The sealing structure may comprise a metal tube. For example, the sealing structure may be an aluminum tube with the heating element disposed within the tube.
[0015] The heating element is typically a resistive heating element. An electric current can be passed through the resistive element to generate heat and thereby heat the sealing structure. The resistive heating element can include any material with a sufficient power density to provide the required heating. For example, the resistive heating element can include one or more of nickel, chromium, iron, or aluminum. For example, the resistive heating element can include nichrome or Kanthal®. The resistive material of the electric heating element is insulated from the sealing structure (and the components to be joined). For example, the heating element can include a mineral insulated heater, such as a magnesium oxide (MgO) coated metal element.
[0016] The sealing structure includes an opening configured to provide access to the heating element, for example, in the case of a tube, the tube may include one or more openings for electrical connection to the heating element.
[0017] Each of the components may include a flange, and the joining element may be configured to be located between the flanges when joined. For example, the sealing structure may form a loop. The sealing structure may be substantially circular. For example, the sealing structure may include a circular aluminum tube.
[0018] The joining element can be configured to provide a permanent hermetic seal between two components for an ultra-high vacuum (UHV) environment. For example, a joining element configured to provide an interlayer aluminum diffusion bond between two components can provide a permanent hermetic seal for UHV.
[0019] The embodiments described herein further provide a method for joining two components. The method includes providing a joining element comprising a sealing structure and a heating element, the heating element being connected to the sealing structure; disposing the joining element between the two components; applying pressure to the joining element through the two components; and heating the sealing structure with the heating element to join the sealing structure to each of the two components and provide a seal therebetween. The joining element may be any of the joining elements described above. Typically, the method includes aluminum interlayer diffusion bonding. For example, the sealing structure may include aluminum, and heating the sealing structure under pressure results in aluminum diffusion bonding between the sealing structure and each of the two components.
[0020] The two components may include flanges. The heating step may include applying a voltage across a heating element. Typically, the heating element is a resistive heating element.
[0021] The sealing structure can be heated to a temperature ranging from 400°C to 600°C for a time ranging from 0.5 hours to 12 hours with a line load (pressure) ranging from 80 N / mm to 120 N / mm. For example, the sealing structure can be heated to a temperature of 500°C using a heating element for a time ranging from 0.5 hours to 1 hour while applying a line load of 100 N / mm. In other embodiments, lower pressures (<100 N / mm) can be used for longer periods of time (>1 hour) to form a sufficient seal.
[0022] Diffusion bonding, especially with aluminum, is usually performed at a rate of 1×10 -4 This requires a furnace enclosure that can be evacuated to a pressure of less than 0.01 mbar (0.01 Pa) and the ability to apply axial forces to the articles being joined, typically on the order of 60 kN, for joining elements with deployed lengths of up to about 600 mm. Such furnaces are expensive and can consume significant amounts of energy. There are also severe limitations on the size of workpieces that can be accommodated in such facilities.
[0023] Embodiments of the present invention can at least partially overcome these problems by directly heating the materials forming the bond. By providing localized heating, less energy may be consumed and the same size limitations may not apply. This may make the joining element and method suitable for sealing between components in a fusion reactor or other large structures where seal integrity in a potentially harsh environment is critical.
[0024] FIG. 2 is a schematic diagram of an embodiment of a joining element 6 comprising a sealing structure, which is an aluminum tube 7 formed into a circle (although any shape of closed loop can be used as the sealing structure), and a heating element, which is a resistance heating element 8 connectable to a power source via output terminals 9. The heating element is surrounded by the sealing structure. The resistance heating element 8 comprises an insulator 10 for electrically insulating the heating element from the sealing structure. The heating element may be a mineral insulated (MI) element, and the insulator 10 may comprise a magnesia (MgO) coating. In use, the joining element is placed between two components to be joined and heated under pressure to create a diffusion bond between the aluminum tube 7 and the components. The components may comprise, for example, metal, ceramic, or glass.
[0025] The resistance heating element 8 may include one or more of nickel, chromium, iron, and aluminum. For example, the resistance heating element 8 may include nichrome or Kanthal®. Nichrome is a family of alloys containing nickel and chromium that can be used as resistance wire for heating elements. Kanthal® is a trademark for the iron-chromium-aluminum (FeCrAl) alloy family used in various resistance and high-temperature applications. Kanthal FeCrAl alloys are composed primarily of iron, chromium (20-30%), and aluminum (4-7.5%). These materials are particularly well-suited for providing sufficient power density for the required heating. The heating element may be formed as a spring with a break for applying a voltage across the spring to generate heating.
[0026] In other embodiments, the sealing structure includes an aluminum coating on another material (e.g., a metal alloy). For example, the sealing structure may include Inconel® or steel (e.g., stainless steel, austenitic stainless steel, iron alloyed with chromium and nickel) with an aluminum coating for diffusion bonding. Inconel® is a trademark for a family of austenitic nickel-chromium-based alloys. Inconel alloys are oxidation-corrosion resistant and suitable for use in extreme environments exposed to high pressures and heat.
[0027] In one embodiment, a mineral-insulated (MI) heating element (i.e., MgO-coated resistance wire) is surrounded by an aluminum tube, which can be welded into a closed loop. In this embodiment, the aluminum tube can be cut at its outer equatorial region so that the tube has a C-shape in cross section. The heating element can then be inserted radially so that it is located inside the aluminum tube, with the cold end and terminal end protruding from the cut. Alternatively, if a single-ended terminated MI heater is used, the tube can have a single tangential drilled hole / hole through which the closed end of the heating element passes, allowing the heated portion to have a closed path around the inside of the aluminum tubular loop.
[0028] FIG. 3 is a schematic cross-sectional view of two metal parts with flanges 11, 12 in the process of being joined by a joining element 6. The joining element 6 includes an outer metal shell 13 (e.g., comprising aluminum) that is an open tube (i.e., a split tube with a C-shaped cross section) that partially surrounds a heating element 14. The heating element 14 may be a resistance heating element. Openings in the metal shell 13 allow for external connections to the heating element 14. The flanges 11, 12 are joined by bolts 15, which apply pressure to the joining element 6 between the flanges 11, 12. Other means, such as a hydraulic press, may be used to compress the metal parts during joining. The joining process may take several hours to form a sufficiently strong seal, and the required time may vary depending on the amount of heat and pressure applied and the specific metals used for joining.
[0029] FIG. 4 shows a schematic cross-sectional view of a portion of a joining element according to one embodiment. The joining element includes an inner heating element 16, a jacket or tube 17 at least partially surrounding the heating element 16, and an outer joining layer 18 overlying the jacket 17. The heating element 16 may include a metal coil or spring with an outer electrically insulating layer. The jacket 17 may be formed from a metal such as Inconel® or stainless steel, or another suitable thermally conductive material that can provide the structural stability and shape required for the joining element. The outer layer 18 provides suitable joining properties for forming a diffusion bond and may include a metal such as aluminum. In use, heat is transferred from the heating element 16 through the metal jacket 17 to the outer layer 18, diffusion bonding the outer layer 18 to the adjacent component under compressive pressure and other suitable environmental conditions, such as a vacuum or inert gas environment.
[0030] In some applications, the seals formed between metal parts must operate in an ultra-high vacuum (UHV) environment. UHV has a pressure of approximately 100 nanopascals (7.5 × 10 -10 UHV is a vacuum state characterized by a pressure below 1000 psi (0.1 psi) (<10 ...
[0031] FIG. 5 is a flowchart showing steps of a method for joining two components. The method includes step S1 of providing a joining element comprising a sealing structure and a heating element, and step S2 of placing the joining element between the components. The joining element can be, for example, a joining element comprising an aluminum tube or sheath and a resistance heating element, such as an insulated coil wire, as described herein. The method further includes step S3 of applying pressure to the joining element through the two components, and step S4 of heating the sealing structure to join each of the two components. For example, the components can be pushed apart by applying a line load of about 100 N / mm to the joining element while the heating element heats the sealing structure to a temperature of about 500° C. At this temperature and pressure, a sufficient seal can be formed in about 0.5 to 1 hour.
[0032] Although specific embodiments have been described, those skilled in the art will recognize that additional embodiments may be implemented that fall within the scope of the claims. Any feature of one embodiment may be combined with the features of other embodiments, as appropriate.
Claims
1. 1. A method of joining two components, comprising: placing a joining element between the two components, the joining element comprising a joining structure and a heating element; compressing the joining element between the two components; heating the joining structure with the heating element to diffusion bond the joining structure to each of the two components to join the two components together; A method comprising:
2. The method of claim 1 , wherein the joining structure comprises a sealing structure that forms a seal between the two components.
3. The method of claim 2 , wherein the two components include a flange of a vacuum chamber.
4. The method of claim 1 , wherein the heating element is disposed inside the joint structure.
5. 5. The method of claim 1, wherein the heating step comprises passing an electric current through the heating element.
6. The method of claim 1 , wherein an outer surface of the joining structure comprises a material suitable for diffusion bonding to each of the two components.
7. The method of claim 6 , wherein the material comprises a metal.
8. The method of claim 6 or 7, wherein the material comprises aluminum.
9. 9. The method of claim 1, wherein the bonded structure is heated to a temperature of 500°C for a period of time ranging from 0.5 hours to 1 hour using the heating element, and the compressing step comprises applying a linear load of about 100 N / mm.
10. A joining element for joining two components, comprising: a joining structure having an outer metal surface; a heating element adjacent to the joining structure; Equipped with The joining element is configured to be positioned between the two components, and the heating element is configured to heat the joining structure in use to join outer metal surfaces of the joining structure to each of the two components.
11. The joining element of claim 10 , wherein the heating element is internal to the joining structure.
12. 12. A joining element according to claim 10 or 11, wherein the joining structure comprises at least partly a jacket around the heating element.
13. The interface element of claim 12 , wherein the outer metal surface of the interface structure comprises a metal coating on the jacket.
14. The joining element according to any one of claims 10 to 13, wherein the outer metal surface comprises aluminum.
15. The joining element of claim 10 , wherein the heating element comprises a mineral insulated heating element.
16. The joining element according to any one of claims 10 to 15, wherein the joining structure comprises a closed loop.
17. The joining element of claim 16 , wherein the joining structure comprises a metal tube.
18. The joining element of claim 16 , wherein the joining structure has a C-shaped cross section.
19. 19. The interface element of claim 10, wherein the interface element comprises a spring-biased metal seal, the heating element comprises a helical spring of the spring-biased metal seal, and the interface element comprises a jacket around at least a portion of the helical spring.
20. A joining element for joining two components, comprising: a joining structure located between the two components; a heating element connected to the joining structure and configured to heat the joining structure sufficiently to join the joining structure to each of the two components; Equipped with The joining structure comprises a metal surface at least partially surrounding the heating element and configured to diffusion bond to the two components.
21. The joining element of claim 20 , wherein the metal surface comprises a shell or a foil.
22. 22. The joining element of claim 20 or 21, wherein the joining structure includes a sealing structure that provides a seal between the two components when used to join them.
23. 23. The joining element of any one of claims 20 to 22, wherein the metal comprises aluminum and the joining structure is configured to aluminum diffusion bond to the two components.