| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an electrode chip from being peeled off from a ground electrode and a center electrode. <P>SOLUTION: This spark plug 100 satisfies 0.8≤A1/A2≤1.9, wherein A1[Hv] is hardness of an electrode chip 70 existing outside of the range of a 0.2 mm radius, and A2[Hv] is hardness of the electrode chip 70 existing within the range of a 0.2 mm radius, with a boundary point PA of a molten pool 23 and the electrode chip 70 on the surface of the spark plug 100 set as a center, on a cross-section passing the center axis O of the electrode chip 70. <P>COPYRIGHT: (C)2011,JPO&INPIT |
