Provided is a humic acid-based coating suspension comprising humic acid, particles of an anti-corrosive pigment or sacrificial metal, and a binder resin dissolved or dispersed in a liquid medium, wherein the humic acid has a weight fraction from 0.1% to 50% based on the total coating suspension weight excluding the liquid medium. Also provided is an object or structure coated at least in part with such a coating.

The object of the invention is to provide a surface-treated steel sheet having a coating having fine adhesiveness to an adhesive on the surface and having excellent corrosion resistance, and a production method thereof. Provided is a surface-treated steel sheet including: a steel sheet; a plated layer containing zinc on the steel sheet; and a coating on the plated layer, wherein the coating contains an acrylic resin, zirconium, vanadium, phosphorus and cobalt, and the acrylic resin has an area ratio of 80 to 100 area % in an area from a surface to a thickness of one-fifth of a film thickness of the coating, and an area ratio of 5 to 50 area % in an area including areas from the film thickness center of the coating to a thickness of one-tenth of the film thickness toward the surface side and toward the plated layer side.

The object of the invention is to provide a surface-treated steel sheet having a coating having fine adhesiveness to an adhesive on the surface and having excellent corrosion resistance, and a production method thereof. Provided is a surface-treated steel sheet including: a steel sheet; a plated layer containing zinc on the steel sheet; and a coating on the plated layer, wherein the coating contains an acrylic resin, zirconium, vanadium, phosphorus and cobalt, and the acrylic resin has an area ratio of 80 to 100 area % in an area from a surface to a thickness of one-fifth of a film thickness of the coating, and an area ratio of 5 to 50 area % in an area including areas from the film thickness center of the coating to a thickness of one-tenth of the film thickness toward the surface side and toward the plated layer side.

A method of providing an anticorrosive coating includes applying a first curable liquid layer to the associated substrate, the first layer having a thickness of at least about 100 micrometers, wherein the first layer includes at least one polymer or at least one monomer, quasi-one-dimensional particles or quasi-two-dimensional particles, sacrificial metal particles, and a solvent, wherein a percolation threshold of the particles is not reached in the presence of the solvent, wherein the percolation threshold of the particles is reached when between about 1% and about 20% of the solvent evaporates, applying a second curable liquid layer having a thickness of at least 100 micrometers on the top of the first layer after the percolation threshold of the particles is reached and viscosity of the first layer increases more than 50%, and allowing the first layer and the second layer to cure simultaneously.

A self-stratifying anticorrosive coating is described herein, including a zinc-rich epoxy, a curing agent chosen from the group consisting of amines, thiols, phenols, and carboxylic anhydrides, a binding agent chosen from the group consisting of aminoalkyl dialkoxysilane, dimethoxysilane, and aminoalkyl trialkoxysilane, a graphitic material, a solvent, a water scavenger, and a moisture-cured siloxane.

An anticorrosive coating includes a first curable liquid layer to the associated substrate, the first layer having a thickness of at least about 100 micrometers, wherein the first layer includes at least one polymer or at least one monomer, quasi-one-dimensional particles or quasi-two-dimensional particles, sacrificial metal particles, and a solvent, wherein a percolation threshold of the particles is not reached in the presence of the solvent, wherein the percolation threshold of the particles is reached when between about 1% and about 20% of the solvent evaporates, applying a second curable liquid layer having a thickness of at least 100 micrometers on the top of the first layer after the percolation threshold of the particles is reached and viscosity of the first layer increases more than 50%, and allowing the first layer and the second layer to cure simultaneously.

An anticorrosive coating includes a first curable liquid layer to the associated substrate, the first layer having a thickness of at least about 100 micrometers, wherein the first layer includes at least one polymer or at least one monomer, quasi-one-dimensional particles or quasi-two-dimensional particles, sacrificial metal particles, and a solvent, wherein a percolation threshold of the particles is not reached in the presence of the solvent, wherein the percolation threshold of the particles is reached when between about 1% and about 20% of the solvent evaporates, applying a second curable liquid layer having a thickness of at least 100 micrometers on the top of the first layer after the percolation threshold of the particles is reached and viscosity of the first layer increases more than 50%, and allowing the first layer and the second layer to cure simultaneously.

An anticorrosive coating includes a first curable liquid layer to the associated substrate, the first layer having a thickness of at least about 100 micrometers, wherein the first layer includes at least one polymer or at least one monomer, quasi-one-dimensional particles or quasi-two-dimensional particles, sacrificial metal particles, and a solvent, wherein a percolation threshold of the particles is not reached in the presence of the solvent, wherein the percolation threshold of the particles is reached when between about 1% and about 20% of the solvent evaporates, applying a second curable liquid layer having a thickness of at least 100 micrometers on the top of the first layer after the percolation threshold of the particles is reached and viscosity of the first layer increases more than 50%, and allowing the first layer and the second layer to cure simultaneously.

Provided are a surface-treated metal sheet excellent in the adhesiveness to a coating treatment film and weldability and a coated member. The surface-treated metal sheet includes a metal sheet and a coating film placed on at least one major surface of the metal sheet; the coating film contains oxide particles, a binder resin, and electrically conductive particles; the amount of electrically conductive particles contained is 5 to 30 mass % relative to the coating film; the oxide particles include non-doped oxide particles and/or doped oxide particles; the non-doped oxide particles include at least one kind selected from the group consisting of zinc oxide particles, tin oxide particles, magnesium oxide particles, calcium oxide particles, and strontium oxide particles; the doped oxide particles include at least one kind selected from the group consisting of doped zinc oxide particles and doped tin oxide particles; the amount of oxide particles contained is 1 to 30 mass %, but is 1 to 10 mass % relative to the coating film in the case of not including doped oxide particles; and the amount of the coating film attached to the major surface is 2 to 20 g/m.sup.2.

Provided are a surface-treated metal sheet excellent in the adhesiveness to a coating treatment film and weldability and a coated member. The surface-treated metal sheet includes a metal sheet and a coating film placed on at least one major surface of the metal sheet; the coating film contains oxide particles, a binder resin, and electrically conductive particles; the amount of electrically conductive particles contained is 5 to 30 mass % relative to the coating film; the oxide particles include non-doped oxide particles and/or doped oxide particles; the non-doped oxide particles include at least one kind selected from the group consisting of zinc oxide particles, tin oxide particles, magnesium oxide particles, calcium oxide particles, and strontium oxide particles; the doped oxide particles include at least one kind selected from the group consisting of doped zinc oxide particles and doped tin oxide particles; the amount of oxide particles contained is 1 to 30 mass %, but is 1 to 10 mass % relative to the coating film in the case of not including doped oxide particles; and the amount of the coating film attached to the major surface is 2 to 20 g/m.sup.2.