| 摘要 |
<p>An aqueous acidic composition for forming a chromium-containing conversion coating on a member having a ferrous metal surface, said aqueous acidic composition being for use as a novel conversion treatment liquid containing a trivalent chromium that can even be used on ferrous members. The composition is characterized by: containing a water-soluble trivalent chromium-containing substance, a water-soluble zinc-containing substance, and a water-soluble polyvalent carboxylic acid compound; on the basis of the total composition, the content of the water-soluble trivalent chromium-containing substance being at least 60mmol/L in terms of chromium, the molar content of the water-soluble zinc-containing substance in terms of zinc being such that the ratio of said content is at least 0.6 to the molar content of the water-soluble trivalent chromium-containing substance in terms of chromium, and the content of the water-soluble polyvalent carboxylic acid compound being at least 55mmol/L in terms of the polyvalent carboxylic acid; and allylamine, polyallylamine, aromatic sulphonic acids, aromatic sulphonic acid formaldehyde condensates, derivatives thereof, fluorine-based substances, hexavalent chromium-containing substances and film-forming organic components not being added thereto.</p> |
