Abstract: The present application is directed to an aqueous passivation composition for the treatment of zinc or zinc alloy coatings, said composition having a pH of from 6.5 to 9 and comprising, based on the weight of the composition: a) at least one base polymer selected from acrylic polymers and non-ionic polyurethane polymers present in an amount of from 5 to 60 wt. % of; b) trivalent Cr(III) ions, present in an amount of from 0.1 to 2.5 wt. %, calculated as Cr; c) ascorbic acid; d) at least one aluminum compound present in an amount of from 0.1 to 2.5 wt. %; and, e) at least one finely divided wax present in the composition in an amount of up to 10 wt. %; wherein said composition is substantially free of nitrate anions and is substantially free of hexavalent chromium (Cr(VI)).

Abstract: The present invention provides an aqueous passivation composition for the treatment of zinc or zinc alloy coatings, comprising: i) phosphoric acid; ii) at least one water-soluble polyphosphonic acid or a water-soluble salt thereof, iii) at least one divalent metal cation (M2+); and, iv) at least one water-soluble or water-dispersible fluoroacid or a salt thereof, wherein said fluoroacid is defined by the following general empirical formula (II): HpTqFrOs ??(II) wherein: each of q and r represents an integer from 1 to 10; each of p and s represents an integer from 0 to 10; and, T represents an element selected from the group consisting of Ti, Zr, Hf, Si, Sn, Al, Ge, and B.

Abstract: An aqueous passivation composition, having a pH of less than 3, comprising: i) a source of trivalent chromium ions; ii) at least one ?-hydroxycarboxylic acid having general formula (I): R1CH(OH)COOH (I); wherein: R1 represents a hydrogen atom, a C1-C4 alkyl group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, a C3-C6 cycloalkyl group or a C6-C10 aryl group; iii) phosphoric acid; iv) at least one water-soluble polyphosphonic acid or a water-soluble salt thereof, said polyphosphonic acid having general formula (II): Z—[—P?O(OH)2]n (II); in which: n is at least 2; and Z is a connecting organic moiety having an effective valency of n, said polyphosphonic acid including at least two phosphonic groups separated by an alkylene bridge having 1 or 2 carbon atoms (C1-C2 alkylene); and v) at least one divalent metal cation; wherein said composition is substantially free of: nitrate and fluoride anions, and hexavalent chromium.