Patent ID: 6838809
Filing Date: 2005-01-04
Classification: C23C,F23Q,H01T

Abstract:
1. a spark plug comprising: a center electrode; an insulator provided outside the center electrode; a metal shell provided outside the insulator; and a ground electrode disposed opposite to the center electrode so as to form a spark discharge gap between the ground electrode and the center electrode, in a state in which the gasket is fitted to a base, end portion of a mount thread portion formed on an outer circumferential surface of the metal shell comprises: a chromate film-containing plug metal component which is a metal component, wherein the metal component has a surface, at least part of the surface being coated with a chromate film comprising at least 95% by weight of trivalent chrome based on 100% by weight of a total chrome content in the chromate film, and the chromate film comprises dye particles.