US 11,757,261 B2
Ground electrode for spark plug and spark plug
Yuji Kaji, Kariya (JP); Nobuo Abe, Kariya (JP); and Naoto Hayashi, Kariya (JP)
Assigned to DENSO CORPORATION, Kariya (JP)
Filed by DENSO CORPORATION, Kariya (JP)
Filed on Nov. 3, 2022, as Appl. No. 17/980,033.
Claims priority of application No. 2021-181199 (JP), filed on Nov. 5, 2021.
Prior Publication US 2023/0147920 A1, May 11, 2023
Int. Cl. H01T 13/32 (2006.01); H01T 13/34 (2006.01); H01T 13/08 (2006.01); H01T 13/39 (2006.01)
CPC H01T 13/39 (2013.01) [H01T 13/32 (2013.01)] 4 Claims
OG exemplary drawing
 
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.