CPC H01T 13/39 (2013.01) [H01T 13/32 (2013.01)] | 4 Claims |
1. A ground electrode for a spark plug, the ground electrode comprising:
a ground electrode body arranged to face a center electrode of the spark plug; and
a discharge portion mounted on the ground electrode body to face the center electrode with a spark gap between the discharge portion and the center electrode,
the discharge portion being made of a platinum-based alloy of platinum, rhodium, and nickel,
a first mass percent of the rhodium contained in the platinum-based alloy of the platinum, the rhodium, and the nickel being within a first range from 2 wt % to 20 wt % inclusive,
a second mass percent of the nickel contained in the platinum-based alloy of the platinum, the rhodium, and the nickel being within a second range from 2.5 wt % to 12 wt % inclusive, wherein:
the platinum-based alloy of the platinum, the rhodium, and the nickel, which has been heated for 50 hours under an atmospheric temperature of 1100° C., has a mean grain diameter that is greater than or equal to 100 μm and less than or equal to 400 μm.
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