Spark plug for use in internal combustion engine

摘要

Spark plug (100) comprises center electrode (120) having distal end portion (100b) configured so that its surface is formed of nickel alloy having nickel (>=80 wt.%) as primary component, and iron (2.5 wt.%) and chromium (10 wt.%) as secondary components. The nickel alloy further includes aluminum (0.2-0.8 wt.%) as a secondary component. Spark plug comprises tubular insulator (140) having axial hole extending in axial direction, center electrode fitted into the axial hole and having distal end portion protruding from a distal end of the insulator, and ground electrode (110) located diametrically outside of the center electrode and positionally related to distal end portion of the insulator and distal end portion of the center electrode. The ground electrode(s) is configured so that portion of spark discharge generated between ground electrode and distal end portion includes creeping discharge along a surface of the distal end portion of the insulator. The distal end portion of center electrode is configured so that its surface is formed of nickel alloy having nickel (>=80 wt.%) as primary component, and iron (2.5 wt.%) and chromium (10 wt.%) as secondary components. The nickel alloy further includes aluminum (0.2-0.8 wt.%) as a secondary component.