| 摘要 |
PROBLEM TO BE SOLVED: To provide a glow plug with a chromate coating film for coating a main metal surface containing a low content of hexavalent chromium, and having anticorrosion performance and heat resistance more excellent compared with those of a conventional chromate coating film, and a manufacturing method therefor. SOLUTION: The surface of a main metal is coated with the chromate coating film of which the contained chromium component is 95 wt.% or more of trivalent chromium, and of which the film thickness is 0.2-0.5μm. The anticorrosion performance is remarkably enhanced and durability against corrosion is imparted to the main metal, by thickening the film thickness as shown hereinbefore, although a film thickness of the conventional trivalent chromium chromate coating film is about 0.1μm of thin film. The corrosion resistance of the main metal is sufficiently maintained even in an environment specific to the glow plug where a temperature is easy to be elevated and where the metal is easy to be attacked with an acid. A chromate treating bath blended with a trivalent chromium salt and a complexing agent with the trivalent chromium salt is preferably used as the chromate treating bath of the present invention. COPYRIGHT: (C)2007,JPO&INPIT
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