An object of the invention is to provide a fishhook for fishing or the like, the fishhook being easily stuck to a fish or the like and being also excellent in durability. The surface of a fishhook is treated with a compound selected from the group consisting of a metallic surfactant having at least one or more hydroxyl groups or hydrolyzable groups, a fluorine-based surface treating agent, a thiol compound and a disulfide compound.

Provided is a low-cost cold rolled steel sheet for zirconium-based chemical conversion treatment that contains Si and Mn and has excellent zirconium-based chemical convertibility even when a relatively large amount of Si-based oxide and Si—Mn-based oxide exists on the steel sheet surface. A cold rolled steel sheet for zirconium-based chemical conversion treatment comprises a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.01% to 1.4%, Mn: 0.14% to 3.2%, P: 0.10% or less, and S: 0.01% or less, with a balance consisting of Fe and inevitable impurities, wherein a Si/Mn mass ratio in steel is 0.10 to 0.7, and a surface coating ratio of steel sheet surface layer oxides having Si content of 10 mass % or more is 40% or less.

Provided is a low-cost cold rolled steel sheet for zirconium-based chemical conversion treatment that contains Si and Mn and has excellent zirconium-based chemical convertibility even when a relatively large amount of Si-based oxide and Si—Mn-based oxide exists on the steel sheet surface. A cold rolled steel sheet for zirconium-based chemical conversion treatment comprises a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.01% to 1.4%, Mn: 0.14% to 3.2%, P: 0.10% or less, and S: 0.01% or less, with a balance consisting of Fe and inevitable impurities, wherein a Si/Mn mass ratio in steel is 0.10 to 0.7, and a surface coating ratio of steel sheet surface layer oxides having Si content of 10 mass % or more is 40% or less.

[Problem] To provide: a coating liquid for forming an insulation coating for grain-oriented electrical steel sheets, which enables the achievement of excellent coating properties including high coating tension and excellent corrosion resistance even without using a chromium compound; a grain-oriented electrical steel sheet; and a method for producing a grain-oriented electrical steel sheet. [Solution] A coating liquid for forming an insulation coating for grain-oriented electrical steel sheets, which contains boric acid and hydrated silicate particles containing aluminum.

[Problem] To provide: a coating liquid for forming an insulation coating for grain-oriented electrical steel sheets, which enables the achievement of excellent coating properties including high coating tension and excellent corrosion resistance even without using a chromium compound; a grain-oriented electrical steel sheet; and a method for producing a grain-oriented electrical steel sheet. [Solution] A coating liquid for forming an insulation coating for grain-oriented electrical steel sheets, which contains boric acid and hydrated silicate particles containing aluminum.

A process for providing a surface of aluminum containing materials with a chromate-free protective coating includes degreasing a surface of an aluminum containing material to produce a degreased surface, treating the degreased surface in a high alkaline treatment immediately subsequent to the degreasing to produce an alkaline treated surface having smut on the surface, and treating the alkaline treated smut surface with a hydrothermal treatment immediately subsequent to the high alkaline treatment.

A process for providing a surface of aluminum containing materials with a chromate-free protective coating includes degreasing a surface of an aluminum containing material to produce a degreased surface, treating the degreased surface in a high alkaline treatment immediately subsequent to the degreasing to produce an alkaline treated surface having smut on the surface, and treating the alkaline treated smut surface with a hydrothermal treatment immediately subsequent to the high alkaline treatment.

A method of improving corrosion and mar resistance of steel components by creating a black magnetite finish, with a medium temperature process, prior to application of a phosphate layer coating.

This invention provides a technique that enables a chemical conversion coating excellent in adhesiveness and corrosion resistance to be formed on or over a magnesium material or magnesium alloy material and use of the technique. The above object is achieved by performing a surface conditioning treatment by using a surface conditioning agent that includes specific dibasic calcium phosphate particles before performing a chemical conversion for forming the chemical conversion coating.

This invention provides a technique that enables a chemical conversion coating excellent in adhesiveness and corrosion resistance to be formed on or over a magnesium material or magnesium alloy material and use of the technique. The above object is achieved by performing a surface conditioning treatment by using a surface conditioning agent that includes specific dibasic calcium phosphate particles before performing a chemical conversion for forming the chemical conversion coating.