Metallic shell for spark plug and spark plug using the same
A metallic shell for a spark plug which metallic shell achieves suppressed elution of hexavalent chromium, and a spark plug including the metallic shell. The spark plug has a metallic shell. The metallic shell includes a tubular metallic shell body; a metal plating layer provided on a surface of the metallic shell body; and a chromium-containing chemical conversion coating layer provided to cover the metal plating layer. The chemical conversion coating layer has a zirconium component content of 0.1 mass % or more.
1. A metallic shell for a spark plug, the metallic shell comprising:
a tubular metallic shell body;
a metal plating layer provided on a surface of the metallic shell body; and
a chromium-containing chemical conversion coating layer provided to cover the metal plating layer, wherein the chemical conversion coating layer has a zirconium component content of 0.1 mass % or more.
2. The metallic shell for a spark plug according to claim 1 , wherein the chemical conversion coating layer has a zirconium component content of 2.0 mass % or less.
3. The metallic shell for a spark plug according to claim 1 , wherein the chemical conversion coating layer further comprises a cobalt component, and the cobalt component content is equal to or lower than the zirconium component content.
4. The metallic shell for a spark plug according claim 1 , wherein the chemical conversion coating layer further comprises a cobalt component and has a cobalt component content of 0.1 mass % or less.
5. A spark plug comprising:
a metallic shell for a spark plug, wherein the metallic shell includes a tubular metallic shell body, a metal plating layer provided on a surface of the metallic shell body, and a chromium-containing chemical conversion coating layer provided to cover the metal plating layer, said chemical conversion coating layer having a zirconium component content of 0.1 mass % or more;
a tubular insulator at least partially disposed in the metallic shell;
a center electrode disposed at a forward end of the insulator; and
a ground electrode joined to the metallic shell and forming a gap between the ground electrode and the center electrode.
6. The spark plug according to claim 5 , wherein the chemical conversion coating layer has a zirconium component content of 2.0 mass % or less.
7. The spark plug according to claim 5 , wherein the chemical conversion coating layer further comprises a cobalt component, and the cobalt component content is equal to or lower than the zirconium component content.
8. The spark plug according claim 5 , wherein the chemical conversion coating layer further comprises a cobalt component and has a cobalt component content of 0.1 mass % or less.