Spark plug electrode member, spark plug, and method for manufacturing spark plug electrode member

Abstract

The present application provides a spark plug electrode member having a grain structure configured to improve corrosion resistance and a spark plug. In one example, the spark plug electrode component includes an ignition surface end plane and an ignition body comprised of a plurality of metal grains. Each die of the plurality of dies has a die axis extending through a longest range of each die. At the ignition surface end plane, at least 30% of the grain axes are oriented non-orthogonally with respect to the ignition surface end plane. In some examples, there are one or more layer planes at the firing surface end plane that deviate from the spark plug axis at a non-orthogonal angle. The spark plug electrode component may be fabricated using an additive manufacturing method.

Description

Technical Field

[0001] The present application generally relates to spark plugs and other ignition devices for internal combustion engines, and more particularly, to spark plug electrode components having an ignition surface. Background Art

[0002] Spark plugs can be used to initiate combustion in an internal combustion engine. A spark plug typically ignites a gas composition, such as an air / fuel mixture, in an engine cylinder or combustion chamber by generating a spark across a spark gap defined between two or more electrodes. The combustion reaction in the engine cylinder is caused by igniting the gas composition with the spark, and this combustion reaction causes the power stroke of the engine. The high temperature, high voltage, rapid repetition of the combustion reaction, and the presence of corrosive materials in the combustion gases can create a harsh environment in which the spark plug operates. This harsh environment can cause erosion and corrosion of the firing pad and electrodes, which over time can have a negative impact on the performance of the spark plug, potentially resulting in misfires or some other undesirable condition.

[0003] To reduce erosion of the spark plug electrodes, various types of noble metals and their alloys have been used, such as those made of platinum and iridium. However, these materials can be expensive. Therefore, spark plug manufacturers sometimes attempt to minimize the amount of noble metal used in the electrodes by using the noble metal material only at the firing tip of the electrode, where the spark jumps across the spark gap. This enables a multi-component spark plug electrode (e.g., noble metal, structural body, core) to withstand high thermal loads and helps to optimize heat dissipation from the spark gap to the cylinder head while resisting spark erosion.

[0004] However, although the noble metal firing tips of multi-component spark plug electrodes can be used to help minimize spark erosion, they are typically manufactured in a manner that causes the grains of the crystal structure to be oriented longitudinally. Figure 1 And Figure 2 An example is schematically shown. More specifically as Figure 2 shown, noble metal components, which are typically made from drawn wire or rolled sheet metal, produce a textured structure in the processing direction D. Given this, there are large grains and few grain boundaries available to resist erosive attack. Having more grain boundaries can help to act as a barrier to erosion because grain boundaries cause orientation perturbations in the atomic lattice. Additionally, orienting the grain boundaries more specifically with respect to the spark gap can further help to minimize erosion. Summary of the Invention

[0005] In one embodiment, a spark plug electrode component is provided that includes an ignition surface end plane and an ignition body composed of a plurality of metal grains. Each of the plurality of grains has a grain axis that extends through the longest extent of each grain. At the ignition surface end plane, at least 30% of the grain axes are oriented non - orthogonally with respect to the ignition surface end plane.

[0006] In some embodiments, most of the grain axes at the ignition surface end plane are oriented at an angle between 5° and 15° or thereabouts with respect to the ignition surface end plane. 90% or more of the grain axes of each of the plurality of grains can be oriented non - orthogonally with respect to the ignition surface end plane, and the average grain diameter of the plurality of grains can be between 5 µm and 20 µm, inclusive of the end values.

[0007] In some embodiments, the ignition body includes a plurality of layers, and the spark plug axis extends orthogonally through the ignition surface end plane, wherein each of the plurality of layers of the ignition body has a layer plane, and one or more layer planes at the ignition surface end plane deviate from the spark plug axis at a non - orthogonal angle.

[0008] In some embodiments, the ignition body is a firing tip, and the ignition surface end plane defines the ignition surface of the firing tip or defines an end face adjacent to an annular ignition surface. The firing tip can be attached to a spark plug electrode. The spark plug electrode can include a plurality of layers, wherein at least some of these layers include a sheath portion and a core portion, and the material composition of the sheath portion is different from the material composition of the core portion. At least some of the layers including the sheath portion and the core portion are oriented at a non - orthogonal angle with respect to the axis extending through the longest extent of the spark plug electrode.

[0009] In some embodiments, the ignition surface end plane is coplanar with the end face of the firing tip. The firing tip can be attached to a ground electrode, and a second firing tip can be attached to a center electrode. The second firing tip includes an ignition surface and an ignition body composed of a plurality of metal grains. Most of the grain axes at the ignition surface of the firing tip and most of the grain axes at the ignition surface of the second firing tip can be symmetric with respect to the spark gap axis. The firing tip and the second firing tip can be an annular ring having a circular spark gap axis. Most of the grain axes at the ignition surface of the firing tip and most of the grain axes at the ignition surface of the second firing tip can be oriented parallel to each other.

[0010] According to another embodiment, a spark plug electrode component is provided that includes an ignition surface having an ignition surface end plane and an ignition body composed of a plurality of layers. The spark plug axis extends orthogonally through the ignition surface end plane, wherein each of the plurality of layers of the ignition body has a layer plane, and one or more layer planes at the ignition surface end plane deviate from the spark plug axis at a non - orthogonal angle.

[0011] In some embodiments, the ignition body is composed of a plurality of metal grains, wherein each of the plurality of grains has a grain axis that extends through the longest extent of each grain. At the ignition surface end plane, at least 30% of the grain axes are oriented non - orthogonally with respect to the ignition surface end plane.

[0012] In some embodiments, the ignition body is a firing tip for a spark plug electrode, and the ignition surface end plane defines the ignition surface of the firing tip or defines an end face adjacent to an annular ignition surface.

[0013] According to another embodiment, an additive manufacturing method for manufacturing a spark plug electrode component is provided. The method includes the steps of: directing a laser or a powder bed at non - orthogonal angles with respect to each other; melting or sintering a layer of powder on the powder bed surface; forming a plurality of layers to form the ignition body. At least some of the plurality of layers intersect the ignition surface end plane.

[0014] In some embodiments, the ignition body is a hollow cylinder, and the method further includes the step of cutting the hollow cylinder into an annular firing tip. The directing step may include directing the powder bed at a non - orthogonal angle by tilting the powder bed with one or more support members.

[0015] The various aspects, embodiments, examples, features, and alternatives set forth in the preceding paragraphs, in the claims, and / or in the following description and drawings can be employed independently or in any combination thereof. For example, features disclosed in connection with one embodiment can be applied to all embodiments where there are no feature incompatibilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Preferred exemplary embodiments will be described below in conjunction with the drawings, where like reference numerals represent like elements, and wherein: Figure 1 is a cross - sectional view of a center electrode according to the prior art; Figure 2 is Figure 1 an enlarged view of the ignition end of the prior - art center electrode shown; Figure 3 is a cross - sectional view of a spark plug according to one embodiment; Figure 4 is Figure 1 an enlarged schematic view of the ignition end of the spark plug of; Figure 5 is an enlarged schematic view of an alternative configuration of the ignition end for a spark plug (such as Figure 3 the spark plug of); Figure 6 shows an ignition surface (such as Figures 3 to 5An enlarged view of the ignition surface of the firing end of the spark plug); Figure 7 Is according to one embodiment Figure 5 An enlarged view of the firing end; Figure 8 Is an enlarged view of the firing end according to another embodiment; Figure 9 Is Figure 5 And Figure 7 A partial view of the end face of the firing end; Figure 10 Shows an example layer that can be used to manufacture a spark plug electrode component; Figure 11 Schematically shows an example manufacturing method that can be used to manufacture a spark plug electrode component; Figure 12 Schematically shows another example manufacturing method that can be used to fabricate a spark plug electrode component; Figure 13 Schematically shows another example manufacturing method that can be used to fabricate a spark plug electrode component; Figure 14 Shows the firing tip obtained from Figure 13 The spark plug electrode component; Figure 15 Shows the grain structure of the prior art; Figure 16 Shows the grain structure according to this embodiment; Figure 17 Shows the grain structure of the prior art; Figure 18 Shows the grain structure according to this embodiment; Figure 19 Shows an example metal grain; Figure 20 Shows another example metal grain; Figure 21 Shows another example metal grain; and Figure 22 Schematically shows an additive manufacturing method. Detailed Description

[0017] The spark plug electrode component of the present application can improve the life of the spark plug by effectively minimizing erosion caused by the spark. As detailed herein, the grain structure at the ignition surface of the spark plug is specifically configured to orient the grain boundaries in a preferential manner while increasing the number of grain boundaries to contribute to enhanced erosion resistance. The grain boundaries can help act as a barrier to either type of erosion because the grain boundaries cause an orientation perturbation of the atomic lattice. If the electrode material is subjected to dynamic changes or high heat loads, grain boundary precipitation can occur, which has a negative impact on the performance and service life of the spark plug. This grain boundary precipitation can cause fracture along the grain boundaries, preventing heat from flowing from the spark gap to the cylinder head. This can lead to overheating of the electrode (pre-ignition) or complete failure of the spark plug. Therefore, strategically configuring the grain structure can help improve the functionality of the spark plug while minimizing spark-induced erosion.

[0018] The spark plug electrode component described herein can be used in spark plugs and other ignition devices, including industrial plugs, aviation igniters, or any other device for igniting a gas mixture in an engine. This includes spark plugs used in automotive internal combustion engines and particularly in engines equipped to provide gasoline direct injection (GDI), engines operating under lean burn strategies, engines operating under fuel efficient strategies, engines operating under emissions reduction strategies, or combinations thereof. Various spark plug electrode components can provide enhanced erosion resistance, effective gasket retention, and a cost-effective solution using noble metals, to cite some possible improvements.

[0019] Reference Figure 3 , the spark plug 12 includes a center electrode 14, an insulator 16, a metal shell 18, and a ground electrode 20. Other components can include a terminal bolt, an internal resistor, various gaskets, and internal seals, all of which are known to those skilled in the art. The center electrode 14 is typically disposed within the axial bore of the insulator 16 at an internal step and can have a terminal portion exposed outside the insulator at the firing end 22 of the spark plug 12. The center electrode 14 and / or the ground electrode 20 can alternatively be configured compared to the configuration specifically shown in the figure (e.g., not a standard J-gap configuration or a ring firing tip on one or more of the electrodes 14, 20). The insulator 16 is typically disposed within the axial bore of the metal shell 18, against an internal step of the shell bore, and has a terminal nose portion that can be at least partially exposed outside the shell at the firing end of the spark plug 12. The insulator 16 is made of a material (such as a ceramic material) that electrically insulates the center electrode 14 from the metal shell 18. The metal shell 18 provides the external structure of the spark plug 12 and has threads for mounting in the engine.

[0020] In one example, the center electrode 14 and / or the ground electrode 20 are made of a non-noble metal-based material that serves as the outer or sheath portion 24 of the body, or more specifically, a nickel (Ni) alloy material, and may include a copper (Cu) or Cu alloy material that serves as the inner core portion 26 of the body. As used herein, non-noble metal-based refers to a material in which 50 wt% or more is not a noble or inert metal (e.g., nickel-based). Similarly, noble metal-based refers to a material in which 50 wt% or more is a noble or inert metal (e.g., platinum-based). Some non-limiting examples of Ni alloy materials that can be used for the center electrode 14, the ground electrode 20, or both include alloys composed of one or more of Ni, chromium (Cr), iron (Fe), manganese (Mn), silicon (Si), or another element; and more specific examples include materials commonly known as Inconel® 600 or 601, which are types of nickel alloys.

[0021] Reference Figure 4 and Figure 5 Referring to the embodiment of the firing end 22 shown, each of the center electrode 14 and the ground electrode 20 includes a spark plug electrode member 28, which in this embodiment is the firing tip 30. In some embodiments, the spark plug electrode member 28 is not a separate firing tip 30 added (e.g., welded) to the center electrode 14 and / or the ground electrode 20, but rather the electrodes 14, 20 themselves. In other embodiments, the spark plug electrode member 28 is an alternatively configured firing tip (e.g., a post or rivet as opposed to an annular ring or firing pad), or a part of the electrodes 14, 20 or an electrode without a separate firing tip at all, to name just a few possible examples. However, in this embodiment, the spark plug electrode member 28 is the firing tip 30 that generally defines the spark gap G.

[0022] Each spark plug electrode member 28 includes an ignition surface 32 adjacent to the spark gap G and has an ignition body 34, which is the firing tip 30 adjacent to the ignition surface 32 and / or the main portion of the electrodes 14, 20. Each spark plug electrode member 28 also has an ignition surface end plane 36. For Figure 3 and Figure 4 the configuration shown, the ignition surface end plane 36 is coplanar with the ignition surface 32 and is generally oriented orthogonally to the longitudinal axis A of the spark plug 12 SP As used herein, terms such as substantially, parallel, orthogonal, etc. are meant to include a tolerance of + / -5° to account for manufacturing tolerances and minor deviations. For a firing tip 30 and / or electrodes 14, 20 having an annular profile 38, the ignition surface end plane 36 is coplanar with the end face 40 of the annular ignition surface 32. Thus, for Figure 4 the embodiment of Figure 5In an embodiment, the ignition surface end plane 36 defines an end face 40 adjacent to the ignition surface 32 of the annular profile 38. Additionally, in some embodiments, there is no separate firing tip 30 such that the ignition surface 32 and the ignition body 34 are an integrated part of the electrodes 14, 20. Thus, the configuration of the firing end 22 can be different from the specifically shown configuration, where such variations are in dimensions and / or configuration.

[0023] Figure 6 is an enlarged view of the ignition body 34 at the ignition surface 32, where metal grains 42 (only a few are labeled for clarity) are schematically shown. As compared with Figure 1 and Figure 2 the grain structure of the prior art shown, as schematically shown in Figure 6 given a processing direction D associated with the ignition surface end plane 36, most of the grains 42 are skewed in an angular orientation with respect to the processing direction D. When analyzed in cross-section, each grain 42 has a grain axis A that extends through the longest extent of each grain 42 G . Different from most of the grain axes A G that are generally parallel to the spark plug axis A SP for the ignition body 34, at the ignition surface 32 or the end face 40, more than 30% or in some specific embodiments, most of the grain axes A G or even more preferably more than 75% or more than 90% of the grain axes A G are angled non - orthogonally with respect to the ignition surface end plane 36. This angle θ is advantageously between 2° and 45°, or more specifically, between 5° and 15° and including 5° to 15°, where about 5° to 7° is easier to manufacture, as detailed further below. By orienting most of the grains 42 such that the grain axis A G is oriented non - orthogonally with respect to the ignition surface 32 and / or the ignition surface end plane 36, the amount of erosion caused by the spark can be minimized since the orientation of the grain boundaries is less sensitive to thermal fracture. Such a rotation of the grain axis A G by about 5° to 10° can help impart boundary strengthening and can even make it possible to do without a separate precious metal firing tip.

[0024] To achieve the configuration of the grain structure 44 and the grains 42, in one embodiment, an additive manufacturing method is used to deposit a plurality of layers 46 in the ignition body 34. Thus, each layer 46 can have a corresponding layer plane 48, and by stacking each layer 46 at an angle θ with respect to the ignition surface end plane 36, an optimized grain structure 44 can be formed at the ignition surface 32. As schematically shown, this structure 44 can result in most of the grain axes A G being oriented orthogonally with respect to each layer plane 48.

[0025] Specific reference Figures 7 to 9 , the angular orientation of the grain structure 44 can be strategically oriented to help minimize spark erosion. In each of these figures, it should be noted that the teachings regarding Figure 6 the grain axis A G herein are applicable, but the grain direction (e.g., the direction in which most of the grain axes A G are located) can vary according to the specific implementation desired. In Figure 7 , the grain direction of the firing tip 30 on the center electrode 14 is opposite to the grain direction of the firing tip on the ground electrode 20. In Figure 8 's embodiment, the orientation is consistent such that the grain structure 44 of the firing tip 30 on the center electrode 14 is generally parallel to the grain structure 44 of the firing tip 30 on the ground electrode 20. As Figure 9 shown, for the annular ring 38, the spark gap axis A SPG is circular and extends through the entire spark gap G. For example, for a standard J-shaped gap, the spark plug axis A SPG generally bifurcates the spark gap G and is linear. Given the opposite skewed orientations of the given grains 42 on either side of the spark gap axis A SPG , the symmetric arrangement shown Figure 7 may be better in avoiding spark-induced erosion.

[0026] In addition to the angled orientation of the grains 42 in the grain structure 44, there are other structural modifications to the grain structure that can contribute to improving erosion resistance. In some embodiments, impurities or defects can help counteract fracture growth and erosion. For example, impurities or defects may include foreign metals, foreign elements, corrosion inhibitors, an increase in the number of grain boundaries, erosion inhibitors, and dispersed precipitates, to name just a few examples. In some embodiments, materials such as ceramics or tungsten can be incorporated, which are generally insoluble in the melt of the other metals that make up the majority of the composition. Impurities that do not completely dissolve in the alloy can be more easily added using powder metallurgy and have a higher quality (homogeneity). In some embodiments, the grain size can be reduced to increase the number of grain boundaries at the ignition surface 32. In one example, the average grain diameter is less than 14 microns, or preferably between 5 microns and 20 microns, with less than 10 microns being preferred. Additionally, the average grain area (e.g., determined by area counting) is less than 75 square microns, or preferably between 50 square microns and 800 square microns, with less than 75 square microns being preferred. This fine grain structure 44, along with the skewed orientation of the grains 42, can help counteract the propagation of thermal fractures and reduce erosion at the spark gap G. This can be attributed in part to the Hall-Petch relationship, where the yield strength can increase as the grain size decreases. Simulated micrographs of the fine grain structure 44 do show grain boundary strengthening that can be achieved without mechanical deformation. Due to the frequent change in direction, these smaller grain sizes help inhibit fracture growth, where the volume of damage is relatively small compared to larger-sized grains. For larger grains, if the fracture occurs along the grain boundary, the erosion rate is greater / faster because there are no obstacles to break the fracture growth. Therefore, longer fractures can form, which can lead to the loss of entire grains or more rapid large-volume loss.

[0027] Figure 10Shows another embodiment of the spark plug electrode component 28, in which the spark plug electrode component is the center electrode 14, although the teachings are also applicable to specific embodiments of the ground electrode 20. The schematic shows one layer 46 of the plurality of layers forming the electrode 14. In an advantageous embodiment, the plurality of layers are formed via additive manufacturing such that each layer 46 is angled or skewed, as described above for the embodiment of the firing tip 30. Layer 46 has a sheath portion 24, preferably made of a non-noble metal-based material of the nickel-based alloy type (such as Inconel® 600 or 601). The sheath portion 24 generally surrounds a core portion 26, which is also preferably made of a non-noble metal-based material such as copper or a copper alloy to assist in transferring heat away from the spark gap G. In some embodiments, at least some of the layers 46 include such a dual-material structure, and in some embodiments, there may not be a core portion, and layer 46 may include only a hollow sheath portion 24, or may be a solid layer with no core portion at all in the assembled spark plug electrode. The layer plane 48 is coplanar with layer 46 to schematically show its angled relationship relative to the spark plug electrode axis A E in this embodiment, the spark plug electrode axis is collinear with the spark plug axis A SP The spark plug electrode axis A E is the axis that extends through the longest extent of the spark plug electrodes 14, 20. Generally, layer 46 will be deposited such that the layer plane 48 is orthogonal to axis A E 、A SP However, in this embodiment, layer 46 is skewed at a non-orthogonal angle θ, as in the previously discussed embodiments.

[0028] The spark plug electrode component 28 of the present application can be used as a noble metal or non-noble metal-based firing tip 30, or as the electrodes 14, 20 themselves. However, one advantage of the grain structure 44 is that the skewed structure at the ignition surface 32 helps prevent erosion caused by the spark, and the amount of noble metal can be reduced. In some embodiments, due to the structural change, the use of noble metals can be completely eliminated. In other embodiments, a more cost-effective noble metal-based material can be used, for example, replacing an Ir alloy with greater than 80 wt% Ir (such as replacing IrRh2.5 with IrPt50) with an alloy having close to 50 wt% or less Ir to significantly reduce the amount of iridium and lower the total cost of the spark plug 12. In another embodiment, PdAu20 is used, and of course other materials are possible.

[0029] Figures 11 to 14 Schematically shows an additive manufacturing method that can be used to manufacture the spark plug electrode component 28. In Figure 11In the illustrated embodiment, the spark plug electrode member 28 is a hollow cylindrical member or tube and is then cut into individual firing tips 30 at the ignition surface end plane 36 (only a few of which are shown for clarity). Given this manufacturing method, the spark plug electrode member 28 has an inclined inner wall 54 and an outer wall 56. In this embodiment, the spark plug electrode member 28 is manufactured at an angle θ of 7°, but can vary as described above with respect to the previous embodiment (see the accompanying description related to Figure 13 and Figure 14 ). Then, the hollow cylinder 58 is cut to a certain length using a cold saw method to form an annular ring 38 for the firing tip 30, for example, providing a grain direction at the ignition surface end plane 36 and throughout the ignition body 34. With this arrangement, given the skew angle of each layer, multiple layers 46 can intersect the ignition surface end plane. Figure 12 Another embodiment is shown where the spark plug electrode member 28 or the firing tip 30 is manufactured directly on the center electrode 14. It should be noted that in this figure, only a few grains 42, layers 46, and layer planes 48 are shown for clarity. This embodiment is better for a pad-like structure compared to the annular structure. In some embodiments, heat treatment can be used before, during, or after the additive manufacturing method to help obtain the desired microstructure. Additionally, various parameters can be adjusted to affect the structure of the spark plug electrode member 28, including but not limited to the position of the part in the powder bed, the position of an optional support structure for heat dissipation during the build process, the cooling rate of the build layers (which may be affected by the powder layer thickness), multiple exposures of the build layers (grain growth), or the temperature of the build plate. To achieve the grain size described herein, the powder size and powder size distribution in the unfused powder can be adjusted. Figure 13 and Figure 14 are schematic diagrams of grain growth in a specific implementation where the spark plug electrode member 28 is an inclined hollow cylinder 58. Figure 13 Another exemplary manufacturing embodiment is shown where the spark plug electrode member 28 is manufactured similar to the embodiment of Figure 11 . However, in this embodiment, instead of tilting the laser, the powder bed 52 is tilted with the help of a support structure 58. As shown by the annular firing tip 30 cut in Figure 14 , this manufacturing method can help impart an angled grain structure 44 at the ignition surface end plane 36. In these figures, the shape of the individual grains 42 is schematically shown as circular, but it should be understood that they may be more elongated / ovoid in shape, and this shape / directionality may be affected by the manufacturing method.

[0030] Figures 15 to 18Shows a comparison between the grain structure 44' of the prior art and the grain structure 44 that can be structurally achieved using the manufacturing methods described herein. A fracture 60' along the coarse-grained boundary of the grain structure 44' ( Figure 15 ) has a much shorter path than a fracture 60 along the fine-grained boundary of the grain structure 44 ( Figure 16 ). When one or more grains 42', 42 are torn off, the area of the coarse-grained structure 44' increases, while when the grain 42 is torn off, the area of the fine-grained structure 44 is much smaller. These comparisons of the areas of the grains 42', 42 are schematically shown in Figure 17 and Figure 18 .

[0031] Figures 19 to 21 Schematically shows the metal grains 42 and the ways to quantify the desired geometry of the grains. The desired geometry of the grains 42 can have a compact shape. Some of this can be attributed to the method, because the change in the position of the laser radiation after each layer 46 can result in the three-dimensional growth of the elongated grains 42. Therefore, about 30% or more of the grains having an elongated shape are preferred. Figure 19 Shows an example area determination, where, as detailed above, the radius is between about 5 microns and 20 microns, and an area less than 75 square microns is preferred. Figure 20 and Figure 21 show more complex shapes. In Figure 20 , as shown in the figure, the maximum radius (r max ) is greater than the minimum radius (r min ). In this specific embodiment, r max is about 1.3 to 1.5 times larger than r min , where r max is between about 5 microns and 20 microns, as described in reference Figure 19 . A similar relationship between r max and r min is also shown in the embodiment of Figure 21 , where two areas A1, A2 are determined separately. Similarly, r max is about 1.3 times larger than r min , where r max is between about 5 microns and 20 microns.

[0032] Figure 22The fabrication of each layer 46 is schematically shown, showing that there are some non-uniformities in additive manufacturing. As described herein, the thickness of layer 46, the laser power, and the grain size of powder 62 will have an impact on the resulting grain structure 44. Due to the non-uniformities of each layer, larger particles of powder 62 can be placed on the build plate. With a flatter design, the larger particles will be carried away by the coater, while more smaller particles can remain in the unevenness of the last-formed layer 46.

[0033] In other embodiments, additive manufacturing is not used, and another manufacturing method is used to impart the grain structure 44. For example, it may be possible to reverse the change in the preferred direction of the structure by subsequent heat treatment, either over the entire component or only at certain points (e.g., at the ignition surface 32), to selectively change the grain structure 44 at certain locations. For example, this can be achieved by laser or electron beam hardening. However, with additive manufacturing, defects such as foreign metals, grain boundaries, corrosion inhibitors, erosion inhibitors, and / or dispersion precipitates can be incorporated. In addition, in traditional manufacturing methods, the grain geometry is physically and elementally related to the cooling and solidification behavior. On the other hand, additive manufacturing allows these limitations to be changed and thus forms a structure that can better withstand spark erosion at least in part due to the grain structure 44.

[0034] It should be understood that the foregoing is a description of one or more preferred exemplary embodiments. The present invention is not limited to the specific embodiments disclosed herein but is defined only by the appended claims. Additionally, the statements contained in the foregoing description relate to specific embodiments and should not be construed as limiting the scope of the invention or the definition of the terms used in the claims, unless the term or phrase is explicitly defined above. For those skilled in the art, various other embodiments and various changes and modifications to the disclosed embodiments will become apparent. All such other embodiments, changes, and modifications are intended to fall within the scope of the appended claims.

[0035] As used in this specification and the claims, the terms "for example", "such as", and "etc.", and the verbs "comprising", "having", "containing", and their other verb forms, when used in conjunction with a list of one or more components or other items, each term shall be construed as open-ended, meaning that the list should not be considered to exclude other, additional components or items. Other terms shall be construed in their broadest reasonable sense unless they are used in a context that requires a different interpretation. Additionally, the term "and / or" shall be construed as inclusive or. Thus, for example, the phrase "A, B, and / or C" shall be construed to cover all of the following cases: "A"; "B"; "C"; "A and B"; "A and C"; "B and C"; and "A, B, and C".

Claims

1. A spark plug electrode component, comprising: Ignition surface end plane; An ignition body comprised of a plurality of metal grains, wherein each of the plurality of grains has a grain axis extending through a longest extent of each grain, wherein at the ignition surface end plane, at least 30% of the grain axes are oriented non-orthogonally relative to the ignition surface end plane. 2 . The spark plug electrode component of claim 1 , wherein a majority of the grain axes at the ignition surface end plane are oriented at an angle of 5° to 15° or therebetween relative to the ignition surface end plane.

3. The spark plug electrode component according to claim 1 or 2, wherein 75% or more, or preferably 90% or more, of the grain axis of each of the plurality of grains is oriented non-orthogonally relative to the ignition surface end plane.

4. A spark plug electrode component according to claim 1 or 2, wherein the ignition body includes a plurality of layers and a spark plug axis extends orthogonally through the ignition surface end plane, wherein each of the plurality of layers of the ignition body has a layer plane, and one or more layer planes at the ignition surface end plane deviate from the spark plug axis at a non-orthogonal angle.

5. The spark plug electrode component according to claim 1 or 2, wherein the ignition body is a firing tip, and the ignition surface end plane defines a ignition surface of the firing tip or defines an end surface adjacent to an annular ignition surface.

6. A spark plug comprising the spark plug electrode component according to claim 5, wherein the firing tip is attached to a spark plug electrode.

7. The spark plug of claim 6 , wherein the spark plug electrode comprises a plurality of layers, wherein at least some of the layers comprise a sheath portion and a core portion, wherein the material composition of the sheath portion is different from the material composition of the core portion, and wherein at least some of the layers comprising the sheath portion and the core portion are oriented at a non-orthogonal angle relative to an axis extending through the longest extent of the spark plug electrode.

8. A spark plug comprising the spark plug electrode component of claim 5, wherein the ignition surface end plane is coplanar with the end surface of the firing tip.

9. A spark plug comprising a spark plug electrode component according to claim 5, wherein the firing tip is attached to a ground electrode and a second firing tip is attached to a center electrode, wherein the second firing tip comprises an ignition surface and an ignition body comprised of a plurality of metal grains, wherein each of the plurality of grains has a grain axis extending through a longest extent of each grain, wherein at the ignition surface, at least 30% of the grain axes are oriented non-orthogonally relative to the ignition surface.

10. The spark plug of claim 9, wherein a majority of the grain axis at the firing surface of the firing tip and a majority of the grain axis at the firing surface of the second firing tip are symmetrical with respect to a spark gap axis.

11. The spark plug of claim 10 wherein said firing tip and said second firing tip are annular rings and said spark gap axis is circular.

12. The spark plug of claim 9 wherein a majority of said grain axes at said firing surface of said firing tip and a majority of said grain axes at said firing surface of said second firing tip are oriented in parallel.

13. An additive manufacturing method for manufacturing a spark plug electrode component, the additive manufacturing method comprising the following steps: directing the laser or powder bed at non-orthogonal angles relative to each other; melting or sintering a layer of powder on the surface of the powder bed; A plurality of layers are formed to form the ignition body, wherein at least some of the plurality of layers intersect the ignition surface end plane.

14. The method of claim 13, wherein the firing body is a hollow cylinder, and the method further comprises the step of cutting the hollow cylinder into an annular firing tip.

15. A method according to claim 13 or 14, wherein the directing step comprises directing the powder bed at the non-orthogonal angle by tilting the powder bed with one or more support members.

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