| 摘要 |
<p>The invention relates to a mixture of substances, a method and a use thereof in the chrome(IV)-free black passivation of zinc alloys. According to said invention, an aqueous acid solution with chrome(III) ions is used and passivation is activated by addition of phosphate ions. Zinc alloys in particular containing nickel, with a nickel proportion of at least 10-12%, are used to form a black chrome layer containing nickel. The phosphate, added as an activator in a low quantity, permits a reaction activation, the removal of nickel ions from the alloy and the homogeneous deposit thereof in the form of black nickel(III) oxide. Nitrate ions and transition metal ions are also used as additional constituents and activators of the chromate bath.</p> |
