Spark plug
A spark plug includes a metallic housing (10), an insulator (20) fixed in the metallic housing (10), a center electrode (30) fixed in the insulator (20), a ground electrode (40) opposed to the centerelectrode (30) via a spark discharge gap (50), and a protective coat formed on the surfaces of a meta...
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Main Authors | , |
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Format | Patent |
Language | Chinese English |
Published |
28.04.2010
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Subjects | |
Online Access | Get full text |
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Summary: | A spark plug includes a metallic housing (10), an insulator (20) fixed in the metallic housing (10), a center electrode (30) fixed in the insulator (20), a ground electrode (40) opposed to the centerelectrode (30) via a spark discharge gap (50), and a protective coat formed on the surfaces of a metallic housing (10) and a gasket (12). The protective coat (15) includes a galvanized film (15a) formed on the surfaces of the metallic housing (10) and the gasket (12)and a chromate film (15b) successively laminated on the galvanized film (15a). The chromate film is hexavalent chromium-free and contains trivalent chromium as a major component. The chromate film (15b) has a film thickness not smaller than 0.05 mum and not greater than 0.18 mum, and the chromate film (15b) contains a metallic component which is robust against oxidation compared with zinc. Furthermore, the chromate film (15b) has a film hardness equal to or less than 1 GPa in the temperature range from a room temperature to 180DEG C. |
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Bibliography: | Application Number: CN200410100610 |