| 摘要 |
A chromium free conversion coating at least equivalent in corrosion protecti ve quality to conventional chromate conver- sion coatings can be formed on metals, particularly galvanized steel, by a d ry- in-place aqueous acidic liquid comprising: (a) a component of anions, each of said anions consisting of (1) at least four fluorine atoms and (ii) at least one atom of an element selected from the group consisting of titanium, zirconium, hafnium, silicon, and boron and, optionally, (iii) one or more oxygen atoms; (b) a component of rations of elements selected from the group consisting of cobalt, magnesium, manganese, zinc, nickel, tin, zirconium, iron, aluminum and copper; the ratio of the total number of rations of this component to the total number of an- ions of component (a) being at least 2:5; and (c) sufficient free acid to gi ve the composition, after dilution with from 1 to 19 times its own weight of water, a pH in the range from 0.05 to 5.0; and, optionally , (d) a composition that will form an organic resinous film upon drying in place.
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