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CN-122000793-A - Spark plug electrode with ruthenium-based material

CN122000793ACN 122000793 ACN122000793 ACN 122000793ACN-122000793-A

Abstract

A spark plug electrode made from a ruthenium-based material having one or more of an equiaxed grain structure, a grain structure with an average grain size less than or equal to 50 μm, a grain structure with an average porosity less than or equal to 2%, and/or a grain structure with an average non-uniformity ratio less than or equal to 6%. In one example, the ruthenium-based material is a binary alloy comprising 1 wt% to 15 wt% rhodium, inclusive, and the balance ruthenium. In various examples, the ruthenium-based material is a ternary alloy comprising 1 wt% to 15 wt% rhodium, inclusive, 0.5 wt% to 5 wt% rhenium, inclusive, and the balance ruthenium. A powder metallurgy method for manufacturing the spark plug electrode is also provided.

Inventors

  • MA SHUWEI
  • Nicholas Ritzma

Assignees

  • 辉门点火系统有限责任公司

Dates

Publication Date
20260508
Application Date
20250708
Priority Date
20240805

Claims (15)

  1. 1. A spark plug electrode (12, 18, 32, 30), the spark plug electrode comprising: Ruthenium-based materials having ruthenium and rhodium, ruthenium being the single largest constituent in weight percent, Wherein the ruthenium-based material has an equiaxed grain structure (102) having an average grain size of less than or equal to 50 μm and an average porosity of less than or equal to 2%.
  2. 2. The spark plug electrode (12, 18, 32, 30) of claim 1 wherein rhodium is the second largest constituent of the ruthenium-based material on a wt.% basis next to ruthenium and is present in the ruthenium-based material at 0.1 wt.% to 35 wt.% inclusive.
  3. 3. The spark plug electrode (12, 18, 32, 30) of claim 2 wherein said ruthenium-based material is a binary alloy comprising 1 to 15 wt% rhodium, inclusive, and the balance ruthenium.
  4. 4. The spark plug electrode (12, 18, 32, 30) of claim 2 wherein at least one of the following metals is the third largest constituent of the ruthenium-based material next to ruthenium and rhodium on a wt.% basis, platinum, palladium, iridium, gold, silver, rhenium, tungsten, tantalum, molybdenum, or niobium.
  5. 5. The spark plug electrode (12, 18, 32, 30) of claim 4 wherein said ruthenium-based material is a ternary alloy comprising 1 to 15 wt% rhodium, inclusive, 0.5 to 5wt% rhenium, inclusive, and the balance ruthenium.
  6. 6. The spark plug electrode (12, 18, 32, 30) of any one of claims 1 to 5, wherein the ruthenium-based material has an average porosity of less than or equal to 1.5%.
  7. 7. The spark plug electrode (12, 18, 32, 30) of any one of claims 1 to 5 wherein said ruthenium-based material has a grain structure with an average non-uniformity ratio of less than or equal to 6% with respect to a maximum solute in said ruthenium-based material on a weight percent basis.
  8. 8. The spark plug electrode (12, 18, 32, 30) of any one of claims 1 to 5, wherein the spark plug electrode is manufactured using a powder metallurgy process that includes sintering a powder mixture to directly form the spark plug electrode into its near-net shape.
  9. 9. A spark plug electrode (12, 18, 32, 30), the spark plug electrode comprising: Ruthenium-based materials having ruthenium and rhodium, ruthenium being the single largest constituent in weight percent, Wherein the ruthenium-based material has an equiaxed grain structure (102) having an average grain size of less than or equal to 50 μm and an average inhomogeneity ratio of less than or equal to 6% with respect to the maximum solute in the ruthenium-based material on weight percent.
  10. 10. The spark plug electrode (12, 18, 32, 30) of claim 9 wherein rhodium is the second largest constituent of the ruthenium-based material on a wt.% basis next to ruthenium and is present in the ruthenium-based material at 0.1 wt.% to 35 wt.% inclusive.
  11. 11. The spark plug electrode (12, 18, 32, 30) of claim 10 wherein said ruthenium-based material is a binary alloy comprising 1 to 15wt% rhodium, inclusive, and the balance ruthenium.
  12. 12. The spark plug electrode (12, 18, 32, 30) of claim 10 wherein at least one of the following metals is the third largest constituent of the ruthenium-based material next to ruthenium and rhodium on a wt.% basis, platinum, palladium, iridium, gold, silver, rhenium, tungsten, tantalum, molybdenum, or niobium.
  13. 13. The spark plug electrode (12, 18, 32, 30) of claim 12 wherein said ruthenium-based material is a ternary alloy comprising 1 to 15 wt% rhodium, inclusive, 0.5 to 5 wt% rhenium, inclusive, and the balance ruthenium.
  14. 14. The spark plug electrode (12, 18, 32, 30) according to any one of claims 9 to 13, wherein the ruthenium-based material has an average porosity of less than or equal to 2%.
  15. 15. The spark plug electrode (12, 18, 32, 30) according to any one of claims 9 to 13, wherein the spark plug electrode is manufactured using a powder metallurgy process comprising sintering a powder mixture to directly form the spark plug electrode into its near-net shape.

Description

Spark plug electrode with ruthenium-based material The present application is a divisional application of chinese patent application number 202510935546.4, entitled "spark plug electrode with ruthenium-based material", filed on application number 2025, month 07, month 08, and claiming priority from U.S. patent application number 18/794,380, filed on application number 2024, month 08, month 05, the contents of which are incorporated herein by reference. Technical Field The present invention relates generally to spark plugs and other ignition devices for internal combustion engines, and in particular to spark plug electrodes. Background Spark plugs may be used to initiate combustion in internal combustion engines. Spark plugs typically ignite gases, such as an air/fuel mixture, in an engine cylinder or combustion chamber by creating a spark across a spark gap defined between two or more electrodes. Ignition of the gas by the spark causes a combustion reaction in the engine cylinder that causes a 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 must operate. Such harsh environments can lead to erosion and corrosion of the electrodes, which over time can negatively impact the performance and durability of the spark plug, potentially resulting in misfire or some other undesirable condition. In order to reduce the erosion and corrosion of the spark plug electrodes, various types of noble metals and alloys thereof have been used. However, these materials can be expensive. Accordingly, spark plug manufacturers often attempt to minimize the amount of precious metal material used by the electrode by using such material only at the firing tip of the electrode where the spark jumps across the spark gap. Firing tips made from platinum and iridium alloys, which have relatively good ductility and can be manufactured using conventional techniques involving drawing and rolling, have been widely used in industry, but are becoming increasingly expensive and economically unfeasible when used with certain applications. A cheaper noble metal substitute is ruthenium. However, ruthenium alloys have a relatively high brittleness, which makes ruthenium alloys difficult to manufacture according to conventional techniques. Thermal and intergranular cracking are just some of the undesirable characteristics that conventional ruthenium-based firing tips may exhibit when such tips are welded or otherwise attached to spark plug electrodes. Fig. 11 shows an example of a ruthenium-based firing tip 510 attached to a nickel-based electrode 512 with a laser weld 514. In the firing tip 510, particularly near the junction with the laser weld 514, a plurality of inter-granular and/or thermal cracks 520 have formed. The skilled artisan will appreciate that cracks, such as intergranular cracks and/or thermal cracks, are undesirable and in some cases, may even cause firing tip 510 to fall off electrode 512. It is therefore desirable to provide a spark plug electrode made from ruthenium-based materials that have robust erosion and corrosion resistance characteristics, as well as improved resistance to inter-granular and/or thermal cracking. Disclosure of Invention According to a first embodiment, there is provided a spark plug electrode comprising a ruthenium-based material having ruthenium and rhodium, the ruthenium being a single largest constituent on a weight percent basis, wherein the ruthenium-based material has an equiaxed grain structure having an average grain size of less than or equal to 50 μm and an average porosity of less than or equal to 2%. According to various embodiments, the spark plug electrode of the first embodiment may have any one or more of the following features, alone or in any technically feasible combination: rhodium is the second largest constituent of the ruthenium-based material, based on weight percent, next to ruthenium, and is present in the ruthenium-based material at 0.1 to 35 weight percent, inclusive; -the ruthenium-based material is a binary alloy comprising 1 to 15 wt% rhodium, inclusive, and the balance ruthenium; At least one of the metals platinum, palladium, iridium, gold, silver, rhenium, tungsten, tantalum, molybdenum or niobium, based on the weight% of the ruthenium-based material, next to ruthenium and rhodium; -the ruthenium-based material is a ternary alloy comprising 1 to 15 wt% rhodium inclusive, 0.5 to 5 wt% rhenium inclusive and the balance ruthenium; the ruthenium-based material has an average grain size of 5 μm to 40 μm inclusive; -the ruthenium-based material has an average porosity of less than or equal to 1.5%; -the ruthenium-based material has a grain structure having an average inhomogeneity ratio of less than or equal to 6% in terms of weight% of the largest solute in the ruthenium-based material; -rhodium on a we