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.

An electrical steel sheet has an insulation coating on a steel sheet surface. The insulation coating includes: a binder consisting of 100 parts by mass of a metal phosphate and 1 to 50 parts by mass of an organic resin having an average particle size of 0.05 to 0.50 m; and a carboxylic acid-containing compound with a carbon number of 2 to 50 in an amount of 0.1 to 10.0 parts by mass based on 100 parts by mass of solids content of the binder. The organic resin is at least one selected from the group consisting of acrylic resins, epoxy resins, and polyester resins. The insulation coating of this electrical steel sheet shows good edge corrosion resistance after blanking.

An electrical steel sheet has an insulation coating on a steel sheet surface. The insulation coating includes: a binder consisting of 100 parts by mass of a metal phosphate and 1 to 50 parts by mass of an organic resin having an average particle size of 0.05 to 0.50 m; and a carboxylic acid-containing compound with a carbon number of 2 to 50 in an amount of 0.1 to 10.0 parts by mass based on 100 parts by mass of solids content of the binder. The organic resin is at least one selected from the group consisting of acrylic resins, epoxy resins, and polyester resins. The insulation coating of this electrical steel sheet shows good edge corrosion resistance after blanking.

A grain-oriented electrical steel sheet includes: a steel sheet; and an amorphous oxide layer that is formed on the steel sheet, in which a glossiness, of a surface is 150% or higher.

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.

An insulating coating film obtained by mixing 0.5 parts by mass to 10 parts by mass of a copolymer of a fluoroolefin and an ethylenically unsaturated compound when converted into a solid content with 100 parts by mass in solid content of a mixture composed of a metal phosphate and a specific organic resin or a mixture composed of colloidal silica and a specific organic resin is designed to be provided on a surface of an electrical steel sheet, and in this manner, it is possible to obtain an electrical steel sheet having good corrosion resistance under a wet environment and having good properties related to the insulating coating film such as a space factor and adhesiveness.

An insulating coating film obtained by mixing 0.5 parts by mass to 10 parts by mass of a copolymer of a fluoroolefin and an ethylenically unsaturated compound when converted into a solid content with 100 parts by mass in solid content of a mixture composed of a metal phosphate and a specific organic resin or a mixture composed of colloidal silica and a specific organic resin is designed to be provided on a surface of an electrical steel sheet, and in this manner, it is possible to obtain an electrical steel sheet having good corrosion resistance under a wet environment and having good properties related to the insulating coating film such as a space factor and adhesiveness.

Provided is a coated aluminum material having a coating film on a surface of an aluminum material, and capable of exerting excellent corrosion resistance even under severe use conditions while being chromium-free. The coating film is formed on a surface of the aluminum material with a silica-containing film including a water dispersible silica, a phosphorus compound, and a silane coupling agent provided therebetween. The silica-containing film includes 0.5 to 35 mass % of a silane coupling agent, and has Si and P contents of 2 to 60, and 0.1 to 6.0 mg/m.sup.2, respectively, and a P/Si mass ratio of P content and Si content of 0.02 to 0.15. Further, provided is a method for producing such a coated aluminum material.