| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug having a center electrode with good heat-transfer performance, the spark plug having high durability against wear of the electrode and excellent contamination resistance, and hardly causing channeling. SOLUTION: The center electrode 2 comprises an electrode base material 2n formed of a Ni alloy that is predominantly composed of Ni and that contains an alloy component (e.g., Cr) capable of forming an oxide semiconductor having an electrical resistivity whose temperature coefficient is negative. By using such a center electrode 2, a corrosion suppressing layer originating from the components of the electrode base material is easily formed on the surface of a front end portion of an insulator 3, so that corrosion (channeling) of the surface of the front end portion of the insulator 3 due to creeping spark discharge can be suppressed effectively. In addition, when the constituent metal of the electrode base material 2n has a thermal conductivity of 17 to 30 W/m×K, the heat transfer performance of the electrode is enhanced, so that durability against wear of the electrode can be improved greatly. COPYRIGHT: (C)2007,JPO&INPIT
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