| 摘要 |
An object of the invention is to provide a spark plug including a ground electrode, a center electrode, and a noble metal tip disposed on at least one of the ground electrode and the center electrode. In this spark plug, since the noble metal tip provided has a sufficiently high wear resistance and a sufficiently high separation resistance, the spark plug has high durability. The spark plug of the present invention includes the center electrode, the ground electrode, and the noble metal tip that is laser-welded to at least one electrode of the center electrode and the ground electrode (the at least one electrode is hereinafter referred to as an electrode). The noble metal tip has a gap forming surface that forms a gap between the gap forming surface and the other electrode. The noble metal tip is joined to the electrode through a fused portion formed by laser welding, and the fused portion includes a first fused portion and a second fused portion. In the first fused portion, the fused portion is exposed at the gap forming surface and/or a second electrode surface opposite a first electrode surface to which the noble metal tip is joined. In the second fused portion, the fused portion is exposed at a side circumferential surface of the noble metal tip. |
