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 (M.sup.2+); 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):

H.sub.pT.sub.qF.sub.rO.sub.s   (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.

A metal connection member including a Mg alloy member composed principally of magnesium, a partner member connected to the Mg alloy member, the partner member being composed principally of a metal nobler than magnesium, and a chemical conversion treatment film that covers a surface of the Mg alloy member and a surface of the partner member with covering a boundary between the Mg alloy member and the partner member.

The invention relates to a process for coating metallic surfaces with a composition containing at least one of a silane, silanol, siloxane or polysiloxane that is capable of condensation, water and optionally an organic solvent. The composition also contains compound containing Ti, Hf, Zr, Al or B; and at least one type of cation or an organic compound d) selected from monomers, oligomers, polymers, copolymers and block copolymers. The coating freshly applied with this composition is rinsed with a fluid and is not dried thoroughly before this rinsing step so that the compound capable of condensation does not condense substantially before the rinsing step.

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 (M.sup.2+); 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):
H.sub.pT.sub.qF.sub.rO.sub.s(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.