METHOD FOR MANUFACTURING AN ELECTRODE FOR AN IGNITION DEVICE

Description

[0001] The invention relates to a method for manufacturing an electrode for an ignition device according to the preamble of claim 1, a method for manufacturing a spark plug according to the preamble of claim 15, a spark plug according to the preamble of claim 16 and an ignition device according to the preamble of claim 18.

[0002] Various ignition devices are known from the prior art, with which an ignitable medium or mixture is ignited by applying a spark from an electrode. The gases expanding during ignition cause a change in pressure conditions, which is then usually converted into mechanical work. Such ignition devices are used, for example, in motor vehicles, gas engines, and other devices known from the prior art.

[0003] Methods for manufacturing such ignition devices are also known in the prior art. In methods known in the prior art, for example in spark plugs, an ignition gap is formed between two electrodes, e.g., between the center and ground electrodes, comprising precious metal electrodes. A potential difference is then applied across the precious metal electrodes, and a spark is generated via the ignition gap. The precious metal electrodes usually consist of platinum or iridium alloys, or other alloys, arranged on a nickel support. In the prior art, the connection between the nickel support and the precious metal electrode is made by laser welding. Starting from the object surface, the laser welding creates a metallurgical, linear connection between the precious metal electrode and the support with a thin bond at the center of the contact surfaces.

[0004] From EP 2738890 A1 (TANAKA PRECIOUS METAL IND) dated June 4, 2014, DE 112019000377 T5 (NGK SPARK PLUG CO) dated September 17, 2020, US 6750597 B1 (SAKURA, A.) dated June 15, 2004, EP 3139457 A1 (NGK SPARK PLUG CO) dated March 8, 2017, DE 112016006310 T5 (NGK SPARK PLUG CO) dated October 11, 2018, US 5 465 022 A (KATOH AKIO [JP] ET AL) dated November 7, 1995 and EP 3 196 995 Al (TANAKA PRECIOUS METAL IND) [JP]) of 26 July 2017, processes and spark plugs are known in which a precious metal electrode is attached to a carrier material by means of a welded connection.

[0005] A disadvantage of the methods known from the prior art is that the connection between the precious metal electrodes and the substrate at the weld seam is prone to corrosion, and therefore special protection is necessary. Such a method for manufacturing a spark plug using a welding process is known, for example, from EP 3694684 A1, in which the resulting weld seam is then subjected to a post-treatment to protect against corrosion.

[0006] Another disadvantage of known joining methods is that welding processes often result in voids in the weld seam, which reduce the joint's strength. Furthermore, welded joints are often prone to cracking in the heat-affected zone, which can also reduce the weld's strength. In practice, it has therefore been shown that ignition devices using prior art typically have a short service life and are highly susceptible to excessive wear, severe corrosion, and, in many cases, detachment of the precious metal disc. Consequently, prior art requires the spark plugs to be inspected or replaced at regular, short intervals, leading to high maintenance costs and frequent downtime, thus severely impacting economical operation.

[0007] Another disadvantage is that when creating an uneven joint between the two materials using a weld, the two materials are only melted at specific points. This leads to distortion and / or internal stresses due to the uneven dissipation of heat along the weld or in the heat-affected zone. During operation, this results in uneven heat dissipation and localized overheating of the joint, as well as mechanical stresses due to thermal expansion in the joint zone, which promotes detachment of the precious metal plate.

[0008] The object of the present invention is therefore to provide a method for manufacturing an ignition device that enables a longer service life for ignition devices, in particular for ignition devices in the form of spark plugs.

[0009] This problem is solved by a method according to the preamble of claim 1 with the characterizing features.

[0010] If the joining temperature is below the melting point of both the substrate and the electrode material, a special bond is formed between the electrode and substrate materials. This occurs through the diffusion of individual atoms or ions from each material into the other, for example, from the substrate into the electrode material or vice versa. These diffusion processes create a particularly strong, planar bond along and within the joining surface.

[0011] The features according to the invention make it possible to create a connection between the carrier material and the electrode material that exhibits high strength due to the planar bond between the two materials. Furthermore, this planar connection in the form of a metallic bond reduces the risk of cracking and corrosion in the joint area, thereby specifically minimizing unplanned or excessively frequent maintenance and avoiding costs associated with replacing spark plugs or parts, or reducing the overall cost of the ignition system or a single spark plug. Uniform heating of the joint surface also prevents the introduction of thermal stresses, thus preventing stress cracks and internal stresses in the planar connection between the electrode material and the carrier material, as well as distortion of the components.

[0012] By uniformly increasing the temperature to the joining temperature and eliminating the need for a spot or line-shaped melt pool in the joining surface, as in fusion welding, it is also possible to better control the heat input and thus to make the components, especially the electrode material, smaller or thinner. Since the electrode material, in particular, consists or can consist of expensive precious metals, this leads to a significant reduction in material costs. Therefore, in contrast to laser welding methods known from the prior art, the inventive method also allows for the processing of electrode material thicknesses of less than 0.5 mm.

[0013] Furthermore, investigations on ignition devices manufactured according to the inventive method have shown that these have a significantly longer service life compared to the prior art.

[0014] In connection with the present invention, the joining time is defined as a period during which the joining temperature is maintained and / or is greater than or equal to a threshold temperature, in particular 30% of the melting temperature of the substrate and / or electrode material, wherein further temperature profiles may also be present at the joining surface before and / or after the joining time. For example, a heating phase and / or a cooling phase may precede or follow the joining time, and / or the joining temperature may be varied within a certain range. In connection with the invention, the joining temperature is not only understood as a constant temperature, but can also be changed during the joining time. The joining temperature is understood to be the temperature(s) at which a bond can be formed between the electrode material and the substrate material.In the course of the investigations underlying the present invention, it was surprisingly discovered that the joining temperature for most of the tested materials is above 30% but below 50% of their melting temperature, in particular the melting temperature of the material with the higher melting temperature. Furthermore, it was found that higher temperatures accelerate the joining process and thus the joining time can be reduced depending on the temperature.

[0015] In the context of the present invention, "planar connection" means that the carrier material and the electrode material form a planar, and in particular a full-surface, and uniform connection in the form of a metallic bond along the entire joining surface, i.e., over the entire area where the carrier material and the electrode material are in contact. The electrodes produced by the manufacturing process according to the invention therefore do not only have linearly connected sections at the edge zones of the joining surface, as in a weld seam, but are at least over a large part of the joining surface, in particular over the entire joining surface, jointly connected to each other in a planar or full-surface and uniform manner.

[0016] Furthermore, a full-surface bond between the electrode material and the substrate material also achieves higher thermal conductivity and thus cooler electrodes in use.

[0017] Any spark erosion can occur undesirably in the edge region of the electrodes in ignition devices, which, in the case of a linear connection, leads to a reduction in service life due to its limitation to the edge of the joining surface. In contrast, spark erosion has a negligible effect in a planar connection, such as with electrodes produced using the inventive method.

[0018] Particularly advantageous embodiments of the method according to the invention are defined in more detail by the features of the dependent claims: Preferably, in the method according to the invention, the amount of heat that is transferred to the joining surface, in particular the carrier material and the electrode material, to raise it to the joining temperature, is generated by means of induction, radiant heat or thermal conduction.

[0019] It can preferably be provided that the joining temperature is maintained for a joining time such that a metallic bond based on a metallic bond is formed without the formation of intermetallic phases between the substrate material and the electrode material, wherein, in particular, the diffusion of atoms and / or ions of the electrode material into the substrate material is greater than or equal to 0.05 µm, especially between 1 µm and 100 µm, and most preferably between 20 µm and 40 µm. The resulting so-called diffusion bond creates a particularly strong metallic bond between the substrate material and the electrode material, which does not cause any intermetallic phases between the two materials. Since no intermetallic phases are formed, there is also no weakening of the materials.the connection between the two materials is prevented, thus preventing the formation of cracks, cavities and other strength-reducing effects.

[0020] In this context, diffusion refers to the depth to which the atoms and / or ions of the substrate material and / or the electrode material penetrate into the other material. This can also be alternatively referred to as diffusion depth.

[0021] It has proven advantageous to press the carrier material and the electrode material together with a minimum surface pressure of 10 mN / mm 2< to 2500 mN / mm 2<, in particular of 100 mN / mm 2< to 600 mN / mm 2<.

[0022] In order to effectively prevent the negative influence of interfering atmospheres and to ensure an advantageous formation of the connection at the joining surface, it may be provided that the process is carried out under vacuum, a reduced pressure, and / or under an oxygen-reduced, in particular oxygen-free, and / or under an inert and / or under a reducing atmosphere, wherein the vacuum, the reduced pressure, and / or the oxygen-reduced, in particular oxygen-free, and / or inert and / or reducing atmosphere is changed during the course of the process.

[0023] In an advantageous embodiment, it can be provided that the joining temperature is 30% to 98%, in particular 50% to 98%, and especially preferably 75% to 95% of the melting temperature of the substrate material and / or the electrode material.

[0024] An effective joining of the two materials can be achieved particularly efficiently by extending the joining time after exceeding the threshold temperature of 30% of the melting temperature of the substrate and / or electrode material to 1 minute to 24 hours, in particular 1 hour to 4 hours, and most preferably 1 hour to 2 hours. It can be provided that the joining time is only measured after a threshold temperature has been exceeded, or that the joining temperature is kept constant and / or above the threshold temperature for the entire joining time.

[0025] In an optional embodiment of the method, it can be provided that the joining surface has a size of 1 mm 2< to 50 mm 2< , in particular 2 mm 2< to 30 mm 2< , most preferably 2 mm 2< to 15 mm 2< .

[0026] The inventive method makes it possible for the electrode material to have a thickness of 0.05 mm to 2 mm, in particular 0.05 mm to 0.5 mm, and most preferably 0.05 mm to 0.25 mm. Thus, the particularly thin design of the electrode material allows the positive properties of the electrode material to be realized at low material costs.

[0027] An effective connection between the two materials is provided, in particular, by using an electrode material from element groups 4 to 11 or from the titanium, vanadium, chromium, manganese, iron, cobalt, nickel, or copper groups, especially platinum, iridium, rhodium, ruthenium, rhenium, or alloys thereof, most preferably PtRh 90 / 10 and IrRh 90 / 10 from Heraeus. In the context of the present invention, "element group" refers to the respective group of the periodic table, also known as main and transition groups, in which all elements have the same number of valence electrons. A definition of the term "element group" or "group of the periodic table" according to the invention can be found in the textbook [Handbook of Mechanical Engineering, Alfred Böge, 2011, ISBN 978-3-8348-1025-0] or on Wikipedia.

[0028] An optional embodiment of the method according to the invention is provided by applying or attaching or introducing a solder material onto and / or next to the joining surface before or after positioning the electrode material on the substrate material, wherein the joining temperature is above the melting temperature of the solder and below the melting temperature of both the substrate material and the electrode material, wherein, in particular, the joining time after exceeding the melting temperature of the solder material is 10 seconds to 2 hours, preferably 1 minute to 60 minutes. By introducing the solder onto and / or next to the joining surface, the two materials form an advantageous, planar connection via the solder material, which is reliably maintained even under the influence of thermal or internal stresses and ignition forces, or when the ignition current flows.The joining time in the soldering process is understood as the period of time during which the temperature of the joining surface, the electrode material and / or the substrate material and / or the solder material is kept above the melting temperature of the solder.

[0029] Advantageously, the solder base material of the solder material is selected from a material of element group 9 to 11 or of the cobalt, nickel or copper group or an alloy thereof, wherein the solder base material of the solder material particularly comprises alloying additions of element groups 4 to 15, wherein the solder material in particular consists of silver, gold or nickel as the solder base material and comprises optional additions such as chromium, silicon, iron, boron, molybdenum, phosphorus, palladium and / or copper or combinations thereof, wherein the solder material is preferably Ag 99.99 or NiCrSiBFe or NiCrSi

[0030] An optional embodiment of the method provides that the carrier material has a recess, wherein the electrode material, when placed against the carrier material, is at least partially recessed in the recess. By forming recesses in the carrier material, the electrode material can be easily positioned, and thus, optionally, the joining surface can be extended from the lateral edges of the electrode material or carrier material onto the side surfaces of the recess.

[0031] Another optional embodiment of the method according to the invention provides that an intermediate material is arranged on the carrier material or on the electrode material between the carrier material and the electrode material, wherein the joining surface is formed between the carrier material and the intermediate material and between the electrode material and the intermediate material, respectively, wherein the joining temperature is below the melting temperature of the carrier material, the electrode material, and the intermediate material, and wherein the carrier material and the intermediate material, as well as the electrode material and the intermediate material, form a planar connection with each other. In this way, materials that would otherwise form a poor bond with each other can also be joined via the intermediate material, thus forming a planar connection in the form of a metallic bond.

[0032] Optionally, the intermediate material can be designed as a diffusion accelerator, in particular silver or copper, whereby the diffusion of atoms and / or ions of the electrode material through the intermediate material into the support material and / or the diffusion of atoms and / or ions of the support material through the intermediate material into the electrode material is accelerated by the intermediate material. The diffusion of atoms and / or ions of the electrode material through the intermediate material into the support material and / or the diffusion of atoms and / or ions of the support material through the intermediate material into the electrode material can be accelerated by the intermediate material designed or acting as a diffusion accelerator.

[0033] Optionally, the substrate material and / or the electrode material and / or the intermediate material can be provided with a mean roughness value Ra of 0.01 µm to 6.3 µm, particularly of 0.02 µm to 0.5 µm, at the joining surface. The advantageous surface properties of the materials result in a particularly beneficial, planar connection between the materials and, in particular, improve diffusion and / or the diffusion bond.

[0034] To enable the simultaneous production of a large number of electrodes, it can be arranged that multiple carrier materials and electrode materials are stacked in pairs, with the carrier materials to be joined in pairs and the electrode materials being separated from each other by a separating material and / or a separating layer. The separating material or separating layer does not bond with the electrode or carrier material during the process, so that the two materials can be easily lifted, detached, or separated from the separating material or separating layer.

[0035] Another aspect of the present invention provides for a method for manufacturing a spark plug which, compared to the prior art, has a longer service life and a connection with higher strength between the electrode material and the carrier material.

[0036] This problem is solved by the characterizing features of claim 15. According to the invention, it is provided that the connection between the carrier and the electrode plate is produced according to a method according to the invention.

[0037] The inventive method for manufacturing the spark plug can be carried out simply and cost-effectively, and thus a strong, flat connection between the electrode plate and the carrier can be produced that is protected against corrosion and cracking.

[0038] Another aspect of the present invention provides for the provision of a spark plug, in particular for internal combustion engines or gas engines, which has an electrode according to the invention or an electrode consisting of an electrode material which is particularly well bonded to the carrier material.

[0039] This problem is solved in a spark plug according to the preamble of claim 16 with the characterizing features. According to the invention, the connection between the carrier and the electrode plate is produced according to a method according to the invention, wherein the carrier is designed as the carrier material and the electrode plate as the electrode material.

[0040] The spark plug according to the invention has a particularly strong connection between the carrier and the electrode, which is protected against negative influences occurring during the ignition process. This allows it to be used with a long service life and reliability even when employed as a high-performance spark plug, where a high electrical potential difference occurs and high thermal resistance is simultaneously required. The spark plug according to the invention can withstand high electrical potential differences and simultaneously high thermal loads or alternating stresses.

[0041] An advantageous embodiment of the spark plug according to the invention can be provided by forming the carrier from a nickel or chromium-nickel alloy or steel, preferably from nickel in pure form, nickel-based alloys, FeCrNi or FeCrNiMo stainless steels, and wherein the electrode plate is formed from a precious metal, in particular platinum, iridium, rhodium, ruthenium, rhenium or an alloy thereof, in particular platinum / rhodium, platinum / rhenium, platinum / iridium, iridium / rhenium or iridium / rhodium alloys, wherein the electrode plate is particularly preferably an alloy of PtRh 90 / 10 or an alloy of IrRh 90 / 10 and the carrier an alloy of VDM Nickel 201 or EN 2.4068.

[0042] Another aspect of the invention provides for an ignition device with an advantageous connection between the carrier and the electrode plate.This problem is solved by the characterizing features of claim 18; according to the invention, it is provided that the carrier and the electrode plate have a planar, in particular a full-surface, uniform connection with each other, wherein in particular the carrier is designed as the carrier material and the electrode plate as the electrode material, wherein a diffusion zone is formed in the area of ​​the planar connection between the carrier and the electrode plate, in which a concentration of the material of the carrier extending from the carrier towards the electrode plate is from 100% to 0% and a concentration of the material of the electrode plate extending from the carrier (towards the electrode plate) is from 0% to 100%, wherein in particular the diffusion depth is greater than or equal to 0.05 µm, in particular between 1 µm and 100 µm, and most preferably between 20 µm and 40 µm.

[0043] Preferably, the support is made of a nickel or chromium-nickel alloy or steel, preferably of nickel in pure form, nickel-based alloys, FeCrNi or FeCrNiMo stainless steel, and wherein the electrode plate is made of a precious metal, in particular platinum, iridium, rhodium, ruthenium, rhenium or an alloy thereof, in particular platinum / rhodium, platinum / rhenium, platinum / iridium, iridium / rhenium or iridium / rhodium alloys, wherein the electrode plate is particularly preferably an alloy of PtRh 90 / 10 and / or the electrode plate an alloy of IrRh 90 / 10 and the support an alloy of VDM Nickel 201 or EN 2.4068.

[0044] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0045] The invention is shown schematically in the drawings below using particularly advantageous but not limiting embodiments and is described by way of example with reference to the drawings: Fig. 1 shows a schematic representation of an electrode produced according to the inventive method, Fig. 1a bis Fig. 1d show different temperature-time diagrams of manufacturing processes for an electrode according to the invention in simplified representation, Fig. 2 shows a schematic representation of an electrode produced using a solder, Fig. 3 shows an electrode with an intermediate material, Fig. 4 shows a schematic view of an electrode with a depression, Fig. 5 shows an image of an electrode according to the invention under the electron microscope (FEI Quanta 3D 200 scanning electron microscope), Fig. 6 shows another image taken under an electron microscope at higher magnification according to Fig. 5, Fig. 7 shows the distribution of the individual elements in the area of ​​the joining surface of an electrode according to Fig. 5 und 6 , Fig. 8 Another image taken under an electron microscope shows an embodiment of an electrode according to the invention. Fig. 9 shows a photograph of the electrode according to Fig. 8 at higher magnification Fig. 10 shows the distribution of elements in the area of ​​the joining surface of an electrode according to Fig. 8 und 9 , Fig. 11 shows an image taken under an electron microscope (JEOL-JSM-IT200-LA with EDX unit) of an electrode produced by soldering according to the invention, Fig.11a shows the temperature profile of the manufacturing process of the in Fig.11 electrode shown, Fig. 11b shows the pressure profile and vacuum conditions of the manufacturing process of the in Fig.11 electrode shown, Fig. 12 shows a diagram of the temperature profile of an embodiment of the manufacturing process for an electrode according to Fig. 5 bis Fig 10 , Fig. 13 shows a diagram of the pressure profile and vacuum conditions of the embodiment of the manufacturing process according to the invention. Fig. 12 , Fig. 14 shows a photograph of a micrograph of an electrode according to the invention, Fig. 15 shows a cross-sectional image of a spark plug electrode from the state of the art, Fig. 16 shows a spark plug according to the invention in schematic representation, Fig. 17 shows an alternative embodiment of the spark plug according to the invention in an isometric view and Fig. 18 an embodiment of the manufacturing process according to the invention for the production of multiple electrodes.

[0046] In Fig. 1 A first electrode according to the invention for an ignition device is shown in a schematic representation. The electrode has a metallic support material 1 which is connected at a joining surface 8 to a similarly metallic electrode material 2. The in Fig. 1 The electrode shown was manufactured according to the inventive method. To manufacture the electrode, the metallic electrode material 2 was applied to the metallic carrier material 1 at a joining surface 8, so that it rests flat against the carrier material 1. The carrier material 1 and the electrode material 2 are pressed together at the joining surface 8 with a defined surface pressure and positioned in a chamber in which a negative pressure, a vacuum, and / or a defined atmosphere can be generated. After positioning the carrier material 1 and the electrode material 2, a negative pressure or a defined atmosphere is applied in the chamber. After applying the defined atmosphere or negative pressure, the joining surface 8 is heated to a joining temperature TF and this temperature is maintained for a defined joining time t F.By pressing the electrode material 2 against the carrier material 1 and heating it to the joining temperature TF, a planar bond between the carrier material 1 and the electrode material 2 is achieved. In the inventive method, the joining temperature TF is below the melting temperature TS of the carrier material 1 and below the melting temperature TS of the electrode material 2.

[0047] The in Fig. 1 The depicted electrode was produced by a so-called diffusion bonding process, wherein the joining temperature TF is always below the melting temperature TS of the support material 1 and below the melting temperature TS of the electrode material 2. The joining temperature TF is maintained for the joining time t F, so that a metallic bond is formed between the support material 1 and the electrode material 2 without the formation of intermetallic phases. Maintaining the joining temperature TF for a joining time t F causes atoms and / or ions from the electrode material 2 to penetrate the support material 1 or vice versa. This so-called diffusion effect was surprisingly observed in experiments underlying the present invention. It was determined that atoms or ions from the electrode material 2 penetrate the support material 1 or vice versa.Depending on the material pairing, ions diffuse from the electrode material 2 into the support material 1 and / or vice versa, achieving a diffusion depth d F of at least 0.05 µm and more.

[0048] As shown in the diagram Fig. 1a As shown, after the electrode material 2 is placed against the support material 1 and the negative pressure or atmospheric pressure is applied, the joining surface 8, or the entire support material 1 and the entire electrode material 2, is heated. After a heating time tA, the joining temperature TF is reached and then maintained for the joining time tF. The joining time tF is maintained between 1 second and 24 hours, with the joining time tF being particularly between 1 h and 4 h, and especially between 1 h and 2 h. After the joining time tF has elapsed, the heating process is terminated and the joining surface 8, or the electrode material 2 and the support material 1, are then cooled for a cooling time tK.According to the invention, the joining temperature TF is between 30% and 98% of the melting temperature TS of the carrier material 1 and / or the electrode material 2, in particular between 50% and 98%, and more preferably between 75% and 95% of the melting temperature TS of the carrier material 1 and / or the electrode material 2. For example, depending on the material pairing, the joining temperature TF can be 77% of the melting temperature of the carrier material 1 and 45% of the melting temperature TS of the electrode material 2.

[0049] In Fig. 1b Another diagram of a possible heating curve is shown. Starting from an initial temperature of approximately room temperature, the temperature T is increased during a heating time tA to a threshold temperature Tthreshold. Upon reaching the threshold temperature Tthreshold, the joining time tF begins, during which the temperature is further increased, for example, to the melting temperature TS of one of the two materials or even beyond, and then lowered again. The temperature T of the materials is then held constant for a period of time and then, after the bond has formed, cooled again for a cooling time tK.

[0050] As in Fig. 1c und 1d The joining temperature TF can optionally be displayed exclusively in the form of a ramp above the threshold temperature Tthreshold, or it can first be kept constant over a period of time and then further increased and / or decreased.

[0051] The joining temperature TF is the temperature above the threshold temperature Tthreshold at which the electrode material 2 and the substrate material 1 begin to form a bond. The joining temperature TF can be defined as follows: Fig. 1a shown as constant or as in the Fig. 1b bis 1d shown to be variable over the joining time t F.

[0052] To form the planar connection between the carrier material 1 and the electrode material 2, the two materials are pressed together at the joining surface 8 with a defined surface pressure during the electrode manufacturing process. According to the invention, it has been found that a minimum surface pressure of 10 mN / mm² to 2500 mN / mm², and in particular of 100 mN / mm² to 600 mN / mm², has an advantageous effect on the connection properties of the carrier material 1 with the electrode material 2.

[0053] In particular, depending on the materials used for the electrode material 2 and the support material 1, the process can be carried out under vacuum, a reduced pressure, and / or an oxygen-reduced, especially oxygen-free, atmosphere. Optionally, the applied atmosphere can also be inert or a reducing atmosphere. In the inventive process for producing an electrode, the joining surface 8 preferably has a size of 1 mm² to 50 mm², particularly 2 mm² to 30 mm², and most preferably 2 mm² to 15 mm².

[0054] Fig. 2 Figure 1 shows a further embodiment of the electrode according to the invention, which was produced by a second embodiment of the manufacturing process according to the invention. To join the carrier material 1 and the electrode material 2, a solder material 13 is additionally applied to or placed next to the joining surface 8, and the joining temperature TF is then increased above the melting temperature TS of the solder and below the melting temperature TS of the carrier material 1 and the electrode material 2. The application of the solder material 13 and the increase of the joining temperature TF above the melting temperature TS of the solder material 13 causes, particularly under reduced pressure or a vacuum, the solder material 13 to melt and be drawn by capillary action into the joining surface 8 or between the electrode material 2 and the carrier material 1, thereby forming a planar connection between the electrode material 2 and the carrier material 1.During the formation of the connection using solder material 13, it was surprisingly discovered that optionally a proportion of atoms and / or ions of the electrode material 2 and / or the support material 1 can also penetrate through the solder material 13 or via the joining surface 8 into the respective other material and improve the connection.

[0055] The solder material 13, or the solder base material, is preferably selected from a material of element groups 9 to 11 or of the cobalt, nickel, or copper group, or an alloy thereof. The solder base material particularly comprises alloying additions of element groups 4 to 15, with silver, gold, or nickel being particularly preferred as the solder base material, and comprising additions of chromium, silicon, boron, iron, molybdenum, phosphorus, palladium, and / or copper, and / or combinations thereof.

[0056] In Fig. 3 Figure 1 shows a schematic view of another electrode produced by an optional embodiment of the inventive method. An intermediate material 12 is arranged between the electrode material 2 and the carrier material 1, and was positioned before the temperature was increased to the joining temperature TF. The intermediate material 12 can be inserted at the joining surface 8 between the carrier material 1 and the electrode material 2, so that the joining surface 8 is formed between the carrier material 1 and the intermediate material 12, and between the electrode material 2 and the intermediate material 12. After applying the defined atmosphere and / or vacuum or reduced pressure, the temperature in the joining surface 8 is then increased.The temperature of the intermediate material 12, the base material 1, and the electrode material 2 is increased to the joining temperature TF, whereby the joining temperature TF is then below the melting temperature TS of the base material 1, below the melting temperature TS of the electrode material 2, and below the melting temperature TS of the intermediate material 12. After maintaining the joining temperature TF for the joining time t F, a planar connection is formed between the base material 1 and the intermediate material 12, and a planar connection is formed between the electrode material 2 and the intermediate material 12. Optionally, atoms or ions of the electrode material 2 may also diffuse through the intermediate material 12 into the base material 1, and / or atoms or ions of the base material 1 may diffuse through the intermediate material 12 into the electrode material 2.

[0057] Optionally, the intermediate material 12 can also be configured as a diffusion accelerator, in which case the intermediate material consists of or comprises a thin layer of copper or silver. The intermediate material 12, configured as a diffusion accelerator, can accelerate the diffusion of atoms and / or ions from the electrode material 2 through the intermediate material 12 into the substrate material 1 and / or the diffusion of atoms and / or ions from the substrate material 1 through the intermediate material 12 into the electrode material 2. It was surprisingly discovered that a thin layer of silver with a thickness of 100 nm accelerated the diffusion by a factor of 40 when the joining temperature TF was approximately 95% of the melting temperature of the silver material.

[0058] Fig. 4 Figure 1 shows a recess 11 formed in the carrier material 1, into which the electrode material 2 is partially recessed when placed against the carrier material 1. This can optionally increase the joining surface 8 beyond the edge of the electrode material 2, thereby optionally facilitating the positioning of the electrode material 2 on the carrier material 1 and contributing to increased joint strength at the joining surface 8. Alternatively, the recess 11 or the penetration of the electrode material 2 into the carrier material 1 can also occur spontaneously during the manufacturing process. It is assumed that, particularly in diffusion processes, the penetration of the atoms or ions of the electrode material 2 into the carrier material 1 causes a partial penetration of the entire electrode material 2 into the carrier material 1, thus creating a recess 11.

[0059] Another one, in Fig. 18 The illustrated embodiment of the method according to the invention provides that a plurality of carrier materials 1 and electrode materials 2 are positioned together in the chamber for applying the defined atmosphere and / or vacuum or negative pressure. A carrier material 1 is placed next to an electrode material 2, and the resulting paired arrangements are positioned, for example, stacked to form a so-called "stack" or at a distance from one another. The carrier materials 1 and electrode materials 2 to be joined in pairs can each be separated from one another by a separating material 19 or a separating layer. The separating material 19 is a material that neither bonds with the electrode material 2 nor with the carrier material 1, or that prevents the joining of carrier materials 1 and electrode materials 2 of other materials arranged in pairs.

[0060] Fig. 5 Figure 1 shows a photograph of the joining surface 8, magnified at 70:1, taken using an FEI Quanta 3D 200 scanning electron microscope, of an electrode produced by the inventive method. The electrode has a support material 1 onto which the electrode material 2 is applied at the joining surface 8, and a planar connection is formed using the inventive method. The electrode material 2 has dimensions of 1.7 mm x 2.2 mm and a thickness of 0.5 mm. The electrode material 2 consists of the platinum-rhodium alloy PtRh 90 / 10 from Heraeus. In this embodiment, the support material 1 consists of the nickel alloy VDM Nickel 201, also known as EN 2.4068.

[0061] Fig. 6 shows an enlarged view of the joining surface 8 of the electrode according to Fig. 5 in increased resolution (1024 x 943 @ 96 dpi, bit depth 24, magnification factor of 250:1). At the joining surface 8, it is visible that atoms or ions of the electrode material 2 have diffused into the support material 1 through the process according to the invention. The diffusion depth dF, i.e., the maximum distance to which an atom or ion of the electrode material 2 has penetrated into the support material 1, is 36.8 µm. The diffusion depth dF was determined from the electron microscope image based on the different contrast or gray coloration at the joining surface 8. The energy-dispersive X-ray spectroscopy (EDX) method from EDAX was used in combination with a solid-state back-scattered electron imaging system (SSBSED) and an ETD (secondary electron detector).

[0062] Fig. 7 Figure 1 shows a representation of the analysis of the material concentration profile of electrode material 2 and carrier material 1 at the joining surface 8. The in Fig. 7 The concentration of the individual elements obtained by energy-dispersive X-ray (EDX) measurement shows that both rhodium (labeled "RhL" via the intensity of the rhodium L-line) and platinum (labeled "PtL" via the intensity of the platinum L-line) have penetrated from the original joining surface 8 into the nickel alloy (labeled "NiK" via the intensity of the nickel K-line) of the substrate material 1 with decreasing concentration. A diffusion zone forms from the joining surface 8 in which nickel atoms / ions, as well as rhodium and platinum ions / atoms, are present in decreasing concentrations along the diffusion depth dF from the original joining surface 8 towards the substrate material 1. Fig. 5 bis Fig. 7 The figures show the surprisingly achieved effect of the manufacturing process according to the invention, in that a diffusion zone forms starting from the joining surface 8, in which atoms or ions of the electrode material 2 penetrate into the carrier material 1 and thereby form a planar connection between the carrier material 1 and the electrode material 2.

[0063] In the Fig. 8 bis Fig. 10 Further electron microscope images of a connection between the support material 1 and the electrode material 2 in an alternative embodiment are shown. The support material 1 consists of the nickel alloy VDM Nickel 201, also known as EN 2.4068, and the electrode material 2 consists of an iridium-rhodium alloy IrRh 90 / 10 from Heraeus. As shown in the Fig. 8 bis Fig. 10 As can be seen, a diffusion zone is formed at the joining surface 8, in which ions or atoms of the electrode material 2 have diffused into the support material 1. The measured diffusion depth dF is 22.5 µm ( Fig. 9). Fig. 8 This shows an image of the joining surface 8 with a resolution of 1024 x 943 @96dpi, bit depth 24 and a magnification factor of 250:1 and Fig. 9 a resolution of 1024 x 943 @96dpi, bit depth 24 with a magnification factor of 1400:1.

[0064] In Fig. 10 The diagram schematically depicts the concentration profile of the individual atoms or ions of the individual materials of the substrate material 1 and the electrode material 2. Starting from the joining surface 8 and moving towards the substrate material 1, the concentration of rhodium and iridium decreases, while the nickel concentration increases. Thus, starting from the joining surface 8, a region forms in the diffusion zone in which rhodium (denoted as "RhL" based on the intensity of the rhodium L-line), iridium (denoted as "IrL" based on the intensity of the iridium L-line), and nickel (denoted as "NiK" based on the intensity of the nickel K-line) atoms or ions are present and form a planar bond between the two materials in the diffusion zone.

[0065] Fig. 11 Figure 1 shows an alternative embodiment of the electrode, which was manufactured using an optional manufacturing process with the aid of a solder material 13. A solder material 13 is arranged between the support material 1 and the electrode material 2 at the joining surface 8, and was applied to the joining surface 8 during the manufacturing process. The application of the solder created a planar connection between the support material 1 and the electrode material 2 via the solder material 13. As shown in Figure 1, the solder material 13 is applied to the electrode. Fig. 11 As can be seen, electrodes produced using solder also exhibit a reliable, planar connection between the carrier material 1 and the electrode material 2. The solder material 13 can optionally be applied before or after positioning the electrode material 2 on the carrier material 1 when creating the planar connection between the electrode material 2 and the carrier material 1, or it can be introduced or applied to the joining surface 8, or to the edge or next to the joining surface 8, during the joining process. In the case of the Fig. 11 In the electrode shown, which is produced using solder, the electrode material 2 consists of PtRh 90 / 10 and the carrier material 1 of VDM Nickel-201 or EN 2.4068. The solder material 13 consists of a silver solder, in this embodiment silver Ag 99.99. The electrode material 2 was applied to the carrier material 1 with a surface pressure of 65 mN / mm² and the solder material 13 was applied to the joining surface. The assembly was positioned under ambient atmosphere and, after evacuation to a vacuum of 8 x 10⁻⁵ mbar (v-line of the Fig. 11b The heating process was started. Upon reaching a temperature of 650°C, an argon atmosphere with a pressure of 10 mbar (p-line of the Fig. 11b ) applied.

[0066] The in Fig. 11a The temperature profile of the heating process, as depicted, was designed such that the positioned arrangement was heated from room temperature to 650°C within 50 minutes, then at a rate of 6°C / minute to a temperature of 1010°C for a holding time of 5 minutes, and subsequently cooled to room temperature. This resulted in a joining time t F of 14 minutes from when the melting temperature TS,solder of the solder material 13 was exceeded until it fell below 960°C. Thus, the melting temperature TS,solder of the solder material 13 was exceeded, but those of the substrate material 1 and the electrode material 2 were not reached. After a cooling process, a micrograph was prepared and examined using a JEOL-JSM-IT200-LA type electron microscope with an EDX unit under high vacuum. The image obtained from the electron microscope examination is presented as Fig. 11 Image shown with a magnification factor of 80:1.

[0067] The in Fig. 11 The depicted surface finish was produced using an abrasive process with the application of foils from Struers (grits 220, 500, 800, 1000, 1200) for approximately 1 minute each, fine grinding on MD Largo with DiaPro Largo 9µ for approximately 5 minutes, polishing on MD Floc with DiaPro Floc 3µ for approximately 3 minutes, and a final polishing on MD Nap with Diapro Nap 1µ for approximately 3 minutes.

[0068] Fig. 12 Figure 1 shows the temperature profile of a manufacturing process according to the invention for a planar connection between the carrier material 1 and the electrode material 2. In this embodiment, the electrode material 2 consists of the platinum-rhodium alloy Pt / Rh 90 / 10 and the carrier material 1 of the nickel alloy VDM Nickel 201 or EN 2.4068. The electrode material 2 was placed on the carrier material 1 at the joining surface 8 and then pressed onto the carrier material 1 with a surface pressure of 310 mN / mm². The two materials, now joined together, were then positioned in a chamber for applying a vacuum of type MOV 643 from PVA, and a vacuum of 1 x 10⁻⁵ mbar, recognizable by the v-line of the figure, was applied. Fig. 13 The electrode was applied to the material. After applying the vacuum, the temperature in the chamber was raised from room temperature to a holding temperature of 930°C over 40 minutes, and then further increased to 1120°C over another 30 minutes. The temperature was applied to the materials via thermal radiation using molybdenum heating elements. After the electrode cooled, it was removed and subjected to electron microscopy using an FEI Quanta 3D 200 scanning electron microscope. Prior to electron microscopy, the electrode was prepared to create a metallographic section and then examined using the microscope. For this purpose, the electrode was embedded using a hot-bed process, cut perpendicular to the joining surface using a wet-cutting process, polished with a diamond suspension, and analyzed under high vacuum using EDX.The results of the investigation, in which the achieved diffusion depth of the platinum and rhodium atoms or ions was found to be 36.8 µm, are in the . Fig. 5 bis 7 depicted.

[0069] The in the Fig. 8 bis Fig. 10 The electrode shown was developed together with the one in Fig. 5 bis 7 the electrode shown according to the previously to Fig. 12 The described manufacturing process was carried out in a single operation. The assembly was positioned under ambient atmosphere. After evacuating the chamber to a vacuum of 5 x 10⁻⁵ < mbar (v-line of the Fig. 13 The heating was carried out up to a holding temperature of 930°C. After a holding time of 30 minutes, the heating was continued at 6.3°C / min until the joining temperature of 1120°C was reached, and after a holding time of 4 hours, down to 830°C under vacuum (1 x 10⁻⁵ < mbar) and further down to room temperature under a nitrogen atmosphere of 500 mbar (p-line of the Fig. 13 ) cooled. The holding time of 4 h at 1120°C corresponds to the joining time t F of 4 h, the joining temperature of 1120°C corresponds to 77% TS of VDM Nickel 201 or EN 2.4068 and 60% TS of PtRh 90 / 10 from Heraeus and approx. 45% TS of IrRh 90 / 10 from Heraeus. The electrode was also embedded using the hot embedding process, separated perpendicular to the joining surface using a wet cutting process, polished with diamond suspension and analyzed under high vacuum using the EDX method. The images produced in the electron microscopy examination are in the Fig. 8 bis Fig. 10 shown, whereby a diffusion depth d F of 22.5 µm of the atoms or ions of iridium and rhodium into the nickel material of the support material 1 was achieved.

[0070] In the Fig. 14 und Fig. 15 are a comparison between an electrode produced by the inventive method ( Fig. 14 ) and an electrode produced using a laser welding process known from the prior art ( Fig. 15 , IrRh 90 / 10 electrode plates on nickel carriers from Bosch, manufactured by laser beam welding) shown. As in Fig. 14 As can be seen, the electrodes produced according to the manufacturing process of the invention form a full-surface connection free of cracks and voids between the electrode material 2 and the carrier material 1, and a strong and permanent bond between the two materials is achieved. As shown in Fig. 15 As can be seen, the electrodes known from the prior art do not form a full-surface connection between the carrier material 1 and the electrode material 2, but rather exhibit a clear material boundary at the joining surface 8. As in Fig. 15 As shown enlarged in the lower left square, the electrodes known from the prior art also exhibit a connection only in the area of ​​the linear weld seam S, but no connection between the substrate material 1 and the electrode material 2 in the area of ​​the joining surface 8 extending beyond its edge zone. Thus, no bond is achieved between the substrate material 1 and the electrode material 2 in the interior of the specimen outside the weld zone, which projects approximately 50 µm to 100 µm into the specimen interior. This is also evident in Fig. 15 The problem is that the electrodes known from the prior art exhibit defects due to the mechanical pressing together of the materials (upper right square, Fig. 15 ), which, according to investigations, have an increased susceptibility to corrosion.

[0071] In comparison of the Fig. 14 und Fig. 15 Analyses conducted using an electron microscope and further investigations of used electrodes have shown that the manufacturing process according to the invention achieves a full-surface bond between the carrier material 1 and the electrode material 2. This results in higher strength and, consequently, a longer service life for the spark plugs or ignition devices produced from the electrodes, in contrast to the prior art. A uniform, full-surface bond between the electrode material and the carrier material according to the inventive process also achieves better heat transfer and thermal conductivity than the prior art, thus improving heat dissipation from the electrodes during operation. Furthermore, the bonding zone is concealed from spark erosion and therefore better protected.

[0072] The recordings of Fig 5 bis Fig 11 as well as Fig. 14 und Fig. 15 were recorded using an FEI Quanta 3D 200 scanning electron microscope with EDX from EDAX in combination with a Solid State Back-Scattered Electron Imaging System (SSBSED) and a secondary electron detector (ETD or Everhart-Thornley detector).

[0073] As in Fig. 17 and 18 Optionally, several electrode materials 2 or electrode plates 7 can also be arranged on a common carrier material 1 and simultaneously connected to it by the method according to the invention.

[0074] The electrodes produced by the inventive method were then installed in spark plugs and subjected to tests in a test unit and under real-world conditions. After several hours of operation, no adverse effects could be detected, in contrast to spark plugs from the prior art. The unit in which the spark plugs were installed was operated at high mean pressure and relatively high temperatures using combustible gas, without any impairment of the connection occurring in the spark plugs according to the invention.

[0075] The ignition devices and spark plugs manufactured according to the inventive method achieved a service life of >4300 h in tests. Spark plugs manufactured according to the prior art by means of welding and installed on the same test unit, and thus continuously exposed to identical process conditions, achieved a service life of <2000 h before failure due to wear or before exceeding the electrical and thermal load limits. The prior art spark plugs were already unusable after 1200 to 1800 h.

[0076] The connection produced by the inventive method between the electrode material 2 and the carrier material 1 was sufficiently strong in the investigations to prevent damage from cracking, hot gas corrosion, spark erosion, or any other effect that would reduce the service life. Such damage would have resulted in the electrode plate 7 or the electrode material 2 falling off and the ignition device or spark plug failing. Furthermore, it was shown that the optimized heat conduction of the planar connection reduces the temperature of the electrode plate 7 or the electrode material 2 compared to ignition devices or spark plugs according to the prior art, thus slowing down the wear of the electrode material 2 and resulting in a longer service life.

[0077] These advantageous effects are due to the interaction of a strong and high-strength bond on the one hand and the (full-)surface bond achieved with the inventive method between the electrode material 2 and the support material 1 on the other.

[0078] In Fig. 16 und Fig. 17 Two spark plugs in two different exemplary embodiments are shown. The in Fig. 16 The spark plug shown has a first electrode 3, which is designed as a center electrode. The spark plug further has a second electrode 4, which is designed as a ground electrode. An ignition gap 6 is formed between the first electrode 3 and the second electrode 4, in which the spark can be generated between the first electrode 3 and the second electrode 4. The first electrode 3 and the second electrode 4 each have a carrier 5, which can be made of a nickel or iron alloy, Inconel, or a refractory metal. Electrode plates 7, oriented towards the ignition gap 6, are arranged on the carrier 5, and the ignition spark is generated between them. The connections between the carrier 5 and the electrode plates 7 were each produced using the previously described methods according to the invention. The carrier 5 is designed as the carrier material 1, and the electrode plate 7 as the electrode material 2.The carrier material 5 consists of the in . Fig. 16 In the illustrated embodiment, the electrode plate 7 is made of a nickel-based material, and the electrode plate 7 is made of a precious metal, an iridium-rhodium alloy. The electrode plates 7 of the electrodes 3, 4 are connected to the support materials 5 via a diffusion bond as described above. Fig. 5 bis Fig. 10 They are described as being fully bonded, but can also be formed using a plumb line, as described above. Fig. 11 described or produced using an intermediate material.

[0079] Fig. 17 Figure 1 shows a further alternative embodiment of the spark plug according to the invention in an isometric view. The spark plug has two electrodes 3, 4, wherein the first electrode 3 is designed as the center electrode and the second electrode 4 as the ground electrode. An ignition electrode 15 extends radially outwards from the first electrode 3. The second electrode 4 has two electrode plates 7 arranged opposite the ignition electrode 15. An ignition gap 6 is formed between the ignition electrode 15 and the four electrode plates 7 arranged on the second electrode 4. The electrode plates 7 are arranged on a carrier 5 of the ground electrode or the second electrode 4 and are connected to it by a manufacturing process according to the invention. The carrier 5 is designed as the carrier material 1 and the electrode plates 7 as the electrode material 2.A full-surface connection was produced between the electrode plates 7 and the carrier 5 according to the inventive method.

[0080] Optional to the in Fig. 16 und Fig. 17 The spark plugs shown can have carriers 5 made of a titanium, nickel, or iron alloy, in particular a nickel or chromium-nickel alloy, stainless steel, for example an FeCrNi alloy, or Inconel, for example NiCrFe, or a refractory metal, for example tungsten. The electrode plates 7 are preferably made of a precious metal, in particular platinum, iridium, rhodium, ruthenium, or an alloy thereof.

[0081] In contrast to spark plugs known from the prior art, the spark plugs according to the invention have a longer service life due to the flat, preferably full-surface, and stronger connection between the electrode material 2 and the carrier material 1 or between the carrier 5 and the electrode plate 7, and therefore allow for higher operating hours and more reliable operation of the spark plugs according to the invention.

[0082] Optional to the in Fig. 16 und Fig. 17 In the illustrated embodiments of the spark plugs, spark plugs according to the invention can also have other shapes, wherein spark plugs according to the invention have a planar, in particular full-surface, and uniform connection between the electrode material 2 and the carrier material 1.

[0083] Alternatively to the in Fig. 16 und Fig. 17Other ignition devices can also be manufactured using the method according to the invention, in addition to the spark plugs shown. These ignition devices have electrodes with a carrier material 1 and an electrode material 2, which form a planar connection using a method according to the invention. Such ignition devices can, for example, have one or more electrode pairs. Such ignition devices can, for example, be ring-gap, hook, or crown spark plugs.

[0084] Optionally, the electrodes produced using the inventive method can also be subjected to a pretreatment for positioning. For example, the electrode material 2 can be spot-welded or fixed to the carrier material 1 by means of spot welding or laser tack welding.

[0085] In the embodiments according to the invention, the amount of heat that is transferred to the joining surface 8, the carrier material 1 and / or the electrode material 2 to increase it to the joining temperature TF can advantageously be generated by means of induction, radiant heat or thermal conduction.

Claims

1. Method for producing an electrode for an ignition device, in particular a spark plug, wherein a metal electrode material (2) is applied to a joining surface (8) on a metal carrier material (1), wherein the carrier material (1) and the electrode material (2) are pressed against one another at the joining surface (8) with a defined surface pressure and are positioned in a chamber in which a negative pressure, in particular a vacuum, and / or a defined atmosphere is generated, wherein a negative pressure and / or a defined atmosphere is applied in the chamber, wherein the joining surface (8) is heated uniformly to a joining temperature (TF), wherein the joining temperature (TF) is maintained for a joining time (tF) so that a connection between the carrier material (1) and the electrode material (2) is produced at the joining surface (8), and the carrier material (1) and the electrode material (2) form a flat, in particular full-surface, uniform connection with one another starting from the joining surface (8), wherein the carrier material (1) consists of a nickel or chromium-nickel alloy or steel material, preferably nickel in its pure form, nickel-based alloys, FeCrNi or FeCrNiMo stainless steels, characterized in that the joining temperature (TF) is below the melting temperature (TS) of the carrier material (1) and the electrode material (2).

2. Method according to claim 1, characterized in that the amount of heat that is transferred to the joining surface (8), in particular the carrier material (1) and the electrode material (2), to raise it to the joining temperature (TF) is produced by means of induction, radiant heat or heat conduction.

3. Method according to claim 1 or 2, characterized in that the joining temperature (TF) is maintained for a joining time (tF) so that a metallic connection in the form of metallic bonds is formed between the carrier material (1) and the electrode material (2) without forming intermetallic phases, wherein in particular the diffusion of atoms and / or ions of the electrode material (2) into the carrier material (1) and / or the diffusion of atoms and / or ions of the carrier material (1) into the electrode material (2) is greater than or equal to 0.05 µm, in particular between 1 µm and 100 µm, and most preferably between 20 µm and 40 µm.

4. Method according to any one of the preceding claims, characterized in that the carrier material (1) and the electrode material (2) are pressed against one another at a minimum surface pressure of 10 mN / mm2 to 2500 mN / mm2, in particular 100 mN / mm2 to 600 mN / mm2.

5. Method according to any one of the preceding claims, characterized in that the method is performed under vacuum, under negative pressure, and / or under an oxygen-reduced, in particular oxygen-free, and / or under an inert and / or under a reducing atmosphere, wherein the vacuum, the negative pressure, and / or the oxygen-reduced, in particular oxygen-free, and / or inert and / or reducing atmosphere is changed during the course of the method, and / or in that the joining temperature (TF) is 30% to 98%, in particular 50% to 98%, most preferably 75% to 95%, of the melting temperature (TS) of the carrier material (1) and / or the electrode material (2).

6. Method according to any one of the preceding claims, characterized in that the joining time (tF) after exceeding a threshold temperature (Tthreshold) of 30% of the melting temperature (TS) of the carrier material (1) and / or the electrode material (2) is 1 min to 24 h, in particular 1 h to 4 h, most preferably 1 h to 2 h.

7. Method according to any one of the preceding claims, characterized in that the joining surface (8) has a size of 1 mm2 to 50 mm2, in particular 2 mm2 to 30 mm2, particularly preferably 2 mm2 to 15 mm2, and / or in that the electrode material (2) has a thickness of 0.05 mm to 2 mm, in particular 0.05 mm to 0.5 mm, most preferably 0.05 mm to 0.25 mm.

8. Method according to any one of the preceding claims, characterized in that the electrode material (2) consists of a material from the element group 4 to 11 or the titanium, vanadium, chromium, manganese, iron, cobalt, nickel or copper group, in particular platinum, iridium, rhodium, ruthenium, rhenium or alloys thereof.

9. Method according to any one of the preceding claims, characterized in that a solder material (13) is applied or attached or introduced onto and / or next to the joining surface (8) before or after positioning the electrode material (2) on the carrier material (1), wherein the joining temperature (TF) is above the melting temperature of the solder and below the melting temperature (TS) of the carrier material (1) and the electrode material (2) respectively, wherein, in particular, the joining time (tF) after exceeding the melting temperature (TS) of the solder material (13) is 10 seconds to 2 hours, preferably 1 minute to 60 minutes.

10. Method according to claim 9, characterized in that the solder base material of the solder material (13) is selected from a material of the element group 9 to 11 or the cobalt, nickel or copper group or an alloy thereof, wherein the solder base material of the solder material (13) has in particular alloy additives from element groups 4 to 15, wherein the solder material (13) consists in particular of silver, gold or nickel as the solder base material and preferably comprises additives of chromium, silicon, boron, iron, molybdenum, phosphorus, palladium and / or copper and / or combinations thereof, wherein the solder material is preferably Ag 99.99 or NiCrSiBFe or NiCrSi.

11. Method according to any one of the preceding claims, characterized in that the carrier material (1) has a recess (11), wherein the electrode material (2), when applied to the carrier material (1), is at least partially sunk into the recess (11).

12. Method according to any one of the preceding claims, characterized in that an intermediate material (12) is arranged on the carrier material (1) or the electrode material (2) between the carrier material (1) and the electrode material (2), wherein the joining surface (8) is formed respectively between the carrier material (1) and the intermediate material (12) and the electrode material (2) and the intermediate material (12), wherein the joining temperature (TF) is below the melting temperature (TS) of the carrier material (1) and the electrode material (2) and the intermediate material (12), wherein the carrier material (1) with the intermediate material (12) and the electrode material (2) with the intermediate material (12) respectively form a flat connection with one another, and / or in that the intermediate material (12) is in the form of a diffusion-accelerating material, in particular silver or copper, wherein the diffusion of atoms and / or ions of the electrode material (2) through the intermediate material (12) into the carrier material (1) and / or the diffusion of atoms and / or ions of the carrier material (1) through the intermediate material (12) into the electrode material (2) is accelerated by the intermediate material (12).

13. Method according to any one of the preceding claims, characterized in that the carrier material (1) and / or the electrode material (2), in particular and / or the intermediate material (12), has an average roughness value Ra of 0.01 µm to 6.3 µm, in particular 0.02 µm to 0.5 µm, at the joining surface (8).

14. Method according to any one of the preceding claims, characterized in that a plurality of carrier materials (1) and electrode materials (2) are arranged in pairs, piled up respectively to make a stack, wherein the carrier materials (1) and electrode materials (2) to be joined in pairs are separated from other pairs by a separating material (19) and / or a separating layer.

15. Method for producing a spark plug, in particular for internal combustion engines or gas engines, wherein a first electrode (3), in particular a center electrode, and a second electrode (4), in particular a ground electrode, are formed, wherein an ignition gap (6) is formed between the first electrode (3) and the second electrode (4), in particular between the center electrode and the ground electrode, wherein a carrier (5) made of a carrier material (1) is formed on the first electrode (3), in particular the center electrode, and / or the second electrode (4), in particular the ground electrode, wherein an electrode platelet (7) consisting of an electrode material (2) and directed towards the ignition gap (6) is arranged on the carrier (5), characterized in that the connection between the carrier (5) and the electrode platelet (7) is produced according to a method according to any one of claims 1 to 14.

16. Spark plug, in particular for internal combustion engines or gas engines, in particular produced according to a method according to claim 15, comprising a first electrode (3), in particular a center electrode, and a second electrode (4), in particular a ground electrode, wherein an ignition gap (6) is formed between the first electrode (3), in particular the center electrode, and the second electrode (4), in particular the ground electrode, wherein the first electrode (3), in particular the center electrode, and / or the second electrode (4), in particular the ground electrode, have a carrier (5), in particular a nickel carrier, on which an electrode platelet (7) directed towards the ignition gap (6) is arranged, characterized in that the connection between the carrier (5) and the electrode platelet (7) is produced according to a method according to claims 1 to 14, wherein the carrier (5) is in the form of a carrier material (1) and the electrode platelet (7) is in the form of an electrode material (2).

17. Spark plug according to claim 16, characterized in that the carrier (5) is made of a nickel or chromium-nickel alloy or steel, preferably of nickel in its pure form, nickel-based alloys, FeCrNi or FeCrNiMo stainless steels, and wherein the electrode platelet (7) is made of a precious metal, in particular platinum, iridium, rhodium, ruthenium, rhenium or an alloy thereof, in particular platinum / rhodium, platinum / rhenium, platinum / iridium, iridium / rhenium or iridium / rhodium alloys, wherein it is most preferred that the electrode platelet (7) has an alloy of PtRh 90 / 10 and the carrier (5) has an alloy of VDM Nickel 201 or EN 2.4068, or the electrode platelet (7) has an alloy of IrRh 90 / 10 and the carrier (5) has an alloy of VDM Nickel 201 or EN 2.4068.

18. Ignition device, in particular for internal combustion engines or gas engines, comprising a first electrode (3), in particular a center electrode, and a second electrode (4), in particular a ground electrode, wherein an ignition gap (6) is formed between the first electrode (3), in particular the center electrode, and the second electrode (4), in particular the ground electrode, wherein the first electrode (3), in particular the center electrode, and / or the second electrode (4), in particular the ground electrode, have a carrier (5), in particular a nickel carrier, on which an electrode platelet (7) directed towards the ignition gap (6) is arranged, characterized in that the carrier (5) and the electrode platelet (7) have a flat, in particular full-surface, uniform connection with one another, wherein the connection between the carrier (5) and the electrode platelet (7) is produced according to a method according to claims 1 to 14, wherein in particular the carrier (5) is in the form of a carrier material (1) and the electrode platelet (7) is in the form of an electrode material (2), wherein a diffusion zone is formed in the region of the flat connection between the carrier (5) and the electrode platelet (7), at which diffusion zone a concentration of the material of the carrier (5) starting from the carrier (5) in the direction of the electrode platelet (7) is from 100% to 0% and a concentration of the material of the electrode platelet (7) starting from the carrier (5) in the direction of the electrode platelet (7) is from 0% to 100%, wherein, in particular, the diffusion depth is greater than or equal to 0.05 µm, in particular between 1 µm and 100 µm, and most preferably between 20 µm and 40 µm.

19. Ignition device according to claim 18, characterized in that the carrier (5) is made of a nickel or chromium-nickel alloy or steel, preferably of nickel in its pure form, nickel-based alloys, FeCrNi or FeCrNiMo stainless steel, and wherein the electrode platelet (7) is made of a precious metal, in particular platinum, iridium, rhodium, ruthenium, rhenium or an alloy thereof, in particular platinum / rhodium, platinum / rhenium, platinum / iridium, iridium / rhenium or iridium / rhodium alloys, wherein it is most preferred that the electrode platelet (7) has an alloy of PtRh 90 / 10 and the carrier (5) has an alloy of VDM Nickel 201 or EN 2.4068, or the electrode platelet (7) has an alloy of IrRh 90 / 10 and the carrier (5) has an alloy of VDM Nickel 201 or EN 2.4068.