Patent ID: 9343876
Filing Date: 2016-05-17
CPC Classification: C22C,H01T

Claim Text:
1. A spark plug comprising: a center electrode; an insulator provided around the center electrode; a metallic shell provided around the insulator; and a ground electrode which is provided such that one end thereof is bonded to the metallic shell, and the other end faces the center electrode, at least one of the center electrode and the ground electrode having thereon an intermediate member which connects the center electrode or the ground electrode to a noble metal tip; the intermediate member having a tip-bonding portion to which the noble metal tip is bonded, and an electrode-bonding portion to which said one of the center electrode or the ground electrode is bonded, said electrode-bonding portion being adjacent to the tip-bonding portion and having a diameter greater than that of the tip-bonding portion; the intermediate member containing nickel (Ni) as a main component, and also containing chromium (Cr) in an amount of 15 to 25 wt. %; the intermediate member further containing, in a surface portion thereof, silicon (Si) in an amount per unit volume of 0.04 mg/mm wherein the following relation is satisfied: 2.5≦Se/St wherein Se represents the area of a region formed by projection of the electrode-bonding portion on an imaginary plane parallel to a bonding surface between the electrode-bonding portion and the ground electrode, and St represents the transverse cross-sectional area of the tip-bonding portion, and wherein the transverse cross-sectional area St of the tip-bonding portion is 0.64 mm