| 摘要 |
PROBLEM TO BE SOLVED: To provide a trivalent black chromate film which has high hardness and consequently is hardly removed even when chromate-treated articles are rubbed with each other. SOLUTION: A trivalent black chromate treating liquid is used for depositing the trivalent black chromate film on zinc or zinc alloy plating containing chromium nitrate, cobalt nitrate and sulfur-combined organic acid, wherein the treatment is performed by using the liquid containing 0.5-10 g/L chromium chloride and 0.01-20 g/L ammonium monohydrogen difluoride. With this treatment, the trivalent black chromate film having high hardness can be deposited. COPYRIGHT: (C)2007,JPO&INPIT
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