The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

A steel substrate coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a zincsulphate-based layerincludes at least one of the compounds selected from among zincsulphate monohydrate, zincsulphate tetrahydrate and zincsulphate heptahydrate, wherein the zincsulphate-based layer has neither zinc hydroxysulphate nor free water molecules nor free hydroxyl groups, the surface density of sulphur in the zincsulphate-based layer being greater than or equal to 0.5 mg/m.sup.2. A corresponding treatment method is provided.

A steel substrate coated on at least one of its faces with a metallic coating based on zinc or its alloys wherein the metallic coating is itself coated with a zincsulphate-based layerincludes at least one of the compounds selected from among zincsulphate monohydrate, zincsulphate tetrahydrate and zincsulphate heptahydrate, wherein the zincsulphate-based layer has neither zinc hydroxysulphate nor free water molecules nor free hydroxyl groups, the surface density of sulphur in the zincsulphate-based layer being greater than or equal to 0.5 mg/m.sup.2. A corresponding treatment method is provided.

The present invention provides an aqueous treatment solution containing sulfate ions SO.sub.4.sup.2 in a concentration greater than or equal to 0.01 mol/l, to treat sheet metal including a steel substrate coated on at least one face with a coating including at least zinc and magnesium to reduce blackening or tarnishing of the sheet metal during storage. The present invention also provides a sheet metal treated with a solution of this type.

The present invention provides an aqueous treatment solution containing sulfate ions SO.sub.4.sup.2 in a concentration greater than or equal to 0.01 mol/l, to treat sheet metal including a steel substrate coated on at least one face with a coating including at least zinc and magnesium to reduce blackening or tarnishing of the sheet metal during storage. The present invention also provides a sheet metal treated with a solution of this type.

A method of making a treated article having a metal surface. The method includes treating the metal surface with a primer composition comprising a secondary or tertiary amino-functional compound having at least two independently selected silane groups to provide a primed metal surface and subsequently treating the primed metal surface with a treatment composition comprising a fluorinated compound represented by formula Rf{X[Si(Y).sub.3x(R).sub.x].sub.y}.sub.z. An article treated by such a method is also disclosed. The use of a secondary or tertiary amino-functional compound having at least two independently selected silane groups as a primer for a metal surface before treatment with the fluorinated silane and a method of treating a metal surface with a treatment composition including the secondary or tertiary amino-functional compound having at least two independently selected silane groups and certain fluorinated silanes are also disclosed.

A method of making a treated article having a metal surface. The method includes treating the metal surface with a primer composition comprising a secondary or tertiary amino-functional compound having at least two independently selected silane groups to provide a primed metal surface and subsequently treating the primed metal surface with a treatment composition comprising a fluorinated compound represented by formula Rf{X[Si(Y).sub.3x(R).sub.x].sub.y}.sub.z. An article treated by such a method is also disclosed. The use of a secondary or tertiary amino-functional compound having at least two independently selected silane groups as a primer for a metal surface before treatment with the fluorinated silane and a method of treating a metal surface with a treatment composition including the secondary or tertiary amino-functional compound having at least two independently selected silane groups and certain fluorinated silanes are also disclosed.

A composite can include a substrate and a conversion coating overlying the substrate and comprising at least one of a zirconium oxide, a hafnium oxide, or a combination thereof. The conversion coating can be formed from a zirconia or hafnia-based complex obtained by reacting at least one of a zirconium ion source, a hafnium ion source, or a combination thereof, with a chelating compound in a reaction and another chelating compound in another reaction.

A composite can include a substrate and a conversion coating overlying the substrate and comprising at least one of a zirconium oxide, a hafnium oxide, or a combination thereof. The conversion coating can be formed from a zirconia or hafnia-based complex obtained by reacting at least one of a zirconium ion source, a hafnium ion source, or a combination thereof, with a chelating compound in a reaction and another chelating compound in another reaction.