NOBLE METAL ALLOY CHIP FOR SPARK PLUG, AND METHOD OF MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a noble metal chip to be mounted on an electrode of a spark plug which is superior than conventional ones in durability and especially in oxidative consumption resistance.

SOLUTION: The noble metal chip fixed to the center electrode chip part of the spark plug is constituted of a core material composed of iridium or iridium alloy, and a covering layer which covers at least a side face of the core material and is formed by including a first metal oxide. The covering layer has a diffusion layer containing iridium and the first metal at the boundary of the core material side. At this time, a protective layer composed of a second metal may be provided on the covering layer.

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