The tendency of a bare metal surface to oxidize (e.g., flash-rust) may be alleviated by contacting the bare metal surface with an aqueous mixture of at least one preformed reaction product obtained by reaction of at least one catechol compound, such as dopamine or a salt thereof, with at least one co-reactant compound functionalized with one or more functional groups reactive with the at least one catechol compound, such as (meth)acryl, primary amino, secondary amino, thiol and/or hydroxyl groups, with polyethyleneimine being an example of a suitable co-reactant compound. Such a rinsing procedure does not interfere with subsequent conversion coating of the metal surface.

The corrosion resistance of conversion-coated metal substrate surfaces is further enhanced by treating such surfaces with aqueous mixtures of preformed reaction products obtained by reacting catechol compounds, such as dopamine or a dopamine salt, and functionalized co-reactant compounds, such as a polyethyleneimine.

The invention relates to a method of preparing a metal oxide/metal composite, comprising depositing a metal oxide from a dispersion in a liquid on a metal surface; or depositing a metal oxide in the presence of a metal from a dispersion in a liquid on a substrate; or depositing a metal oxide from a metal salt solution on a metal substrate. The metal oxide/metal composites obtained by the process show synergistic antimicrobial activity due to release of high concentrations of redox active species (ROS) at the metal oxide/metal heterojunction. The invention also relates to use of the metal oxide/metal composite as an antimicrobial coating.

The invention relates to a method of preparing a metal oxide/metal composite, comprising depositing a metal oxide from a dispersion in a liquid on a metal surface; or depositing a metal oxide in the presence of a metal from a dispersion in a liquid on a substrate; or depositing a metal oxide from a metal salt solution on a metal substrate. The metal oxide/metal composites obtained by the process show synergistic antimicrobial activity due to release of high concentrations of redox active species (ROS) at the metal oxide/metal heterojunction. The invention also relates to use of the metal oxide/metal composite as an antimicrobial coating.

Disclosed is a surface-treatment solution for producing a zinc or zinc alloy coated steel sheet with a surface-coating layer that does not contain a chromium compound in the surface-coating layer and that is excellent in all of heat discoloration resistance, heat cracking resistance, planar part anti-corrosion property, corrosion resistance after alkali degreasing, blackening resistance, stack blackening resistance, anti-water stain property, solvent resistance, perspiration resistance, coating adhesion property, and storage stability. The disclosed surface-treatment solution contains a glycidyl group-containing silane coupling agent (A), a tetraalkoxysilane (B), a zirconium carbonate compound (C), and an anionic polyurethane resin (D) having a glass transition temperature (Tg) of 80 C. to 130 C., a vanadium compound (E), a molybdic acid compound (F), and water, the surface-treatment solution having a pH of 8.0 to 10.0, and the amount of each component satisfying a predetermined relationship.

Disclosed is a surface-treatment solution for producing a zinc or zinc alloy coated steel sheet with a surface-coating layer that does not contain a chromium compound in the surface-coating layer and that is excellent in all of heat discoloration resistance, heat cracking resistance, planar part anti-corrosion property, corrosion resistance after alkali degreasing, blackening resistance, stack blackening resistance, anti-water stain property, solvent resistance, perspiration resistance, coating adhesion property, and storage stability. The disclosed surface-treatment solution contains a glycidyl group-containing silane coupling agent (A), a tetraalkoxysilane (B), a zirconium carbonate compound (C), and an anionic polyurethane resin (D) having a glass transition temperature (Tg) of 80 C. to 130 C., a vanadium compound (E), a molybdic acid compound (F), and water, the surface-treatment solution having a pH of 8.0 to 10.0, and the amount of each component satisfying a predetermined relationship.

According to one aspect of the present invention, there is provided a chemical conversion coated metal sheet for non-condensed thermoplastic resin bonding, the chemical conversion coated metal sheet including a metal substrate and a chemical conversion coating film disposed on at least one surface of the metal substrate, in which the chemical conversion coating film is obtained by coating the metal substrate with a coating liquid that contains an ethylene-acrylic acid copolymer, colloidal silica, and a silane coupling agent. The ethylene-acrylic acid copolymer has an acrylic acid content of 10 mass % or more and a melt flow rate of 80 g/10 min or less.

It has been found that the chemical reactivity of the metal surface of heat exchangers with coolants in presence of nitrites can be reduced by the addition of additives such as phosphonates or phosphinates. Aluminum, other Group III metals, as well as other metals commonly used in cooling systems, such as those of automobile engines, may thus be effectively protected.

It has been found that the chemical reactivity of the metal surface of heat exchangers with coolants in presence of nitrites can be reduced by the addition of additives such as phosphonates or phosphinates. Aluminum, other Group III metals, as well as other metals commonly used in cooling systems, such as those of automobile engines, may thus be effectively protected.

The invention relates to a wet-chemical pretreatment of zinc surfaces prior to applying a corrosion-protection coating, which deposits a thin inorganic coating of oxide and/or metallic iron. An iron layer structure which is applied according to the invention, hereinafter referred to as ferrization, improves the achievable corrosion protection of wet-chemical conversion coatings on zinc surfaces. Furthermore, the ferrization process causes both a reduction of the contact corrosion of joined metal components which have zinc and iron surfaces as well as a reduction of corrosive coating migration on cut edges of galvanized steel strips with coating layer structures. In particular, the invention relates to an alkaline composition containing an iron ion source, a reducing agent based on oxoacids of nitrogen and phosphorus, and water-soluble organic carboxylic acids with an amino group at the , , or position with respect to the acid group and/or the water-soluble salts thereof.