Patent attributes
A spark plug having a metal shell, center electrode and a ground electrode. The ground electrode includes an electrode base portion extending from a front end portion of the metal shell toward the front, a bent portion connected at one end thereof to a front end of the electrode base portion and an electrode distal end portion extending from the other end of the bent portion and forming a spark discharge gap with a center electrode. The ground electrode has a base material and a coating layer applied to the base material. The coating layer is formed on at least a front end face and an outer circumferential surface other than a center-electrode-side surface of the electrode distal end portion of the ground electrode. The base material of the ground electrode is exposed at least at a part of the electrode base portion.
