| 摘要 |
<p>A spark plug of the present invention is made of an Ir alloy including a specific amount of (1)Rh, (2)Pt, or (3) Rh and Pt or Rh and Ru. The spark plug comprises tips for a center electrode and for a ground electrode that are each 0.6 to 1.8 mm in diameter and 0.2 to 0.7 mm in thickness and for an interlayer made of an Ir alloy including Ni of 40 mass % that has a diameter slightly larger or smaller than that of each tip for the center electrode and for the ground electrode and has a thickness of 0.1 to 0.6 mm. These tips can be manufactured according to the powder processing method, the dissolution method, and so on. The tip for the center electrode is joined to the end surface of the basic body of the center electrode, which is made of a Ni alloy (Inconel 600), according to laser welding. The tip for the interlayer and the tip for the ground electrode are brought into contact with a predetermined position of the ground electrode, and are joined while being pressed according to electric resistance welding. Other parts, such as an insulator and main metal fittings, are each made of general materials and have a general structure. This spark plug is excellent in resistance to lead corrosion, and the tip for the ground electrode is prevented from peeling and falling off from the base because of a thermal expansion difference. <IMAGE></p> |
