Abstract: A solution for treating a surface of an iron material includes (a) zirconium fluoride; (b) ion of a rare earth element and/or a compound containing a rare earth element; (c) a polyallylamine; (d) aluminum ion; and (e) free fluorine ion. Zirconium in the component (a) is at a weight concentration A of 10 to 1000 ppm. The ratio K of the weight concentration B of the rare earth element in the component (b) to the weight concentration A (B/A) is 0.1 to 30. The component (d) is at a weight concentration D of 50 to 250 ppm. The component (e) is at a weight concentration E of 0.5 to 30 ppm. A coating having excellent corrosion resistance before and after the subsequent coating can be deposited on the surface of an iron material by using the surface treating solution which does not contain environmentally harmful ingredients.

Abstract: A method is provided for chemical conversion treatment by which a chemical conversion layer attaining satisfactory substrate-covering properties, adhesion to coating and corrosion resistance can be formed on any metal structure surface. More specifically, a method for chemical conversion treatment is provided by treating a metal structure with an agent for chemical conversion treatment, in which the agent contains zirconium, fluorine, an amino-containing alkoxysilane, and a hydroxyl-containing alkoxysilane with the contents of zirconium and the amino-containing alkoxysilane being 100 to 700 ppm in terms of metal and 50 to 500 ppm in terms of solid matter respectively at a fluorine/zirconium molar ratio of 3.5 to 7.0 and has a pH of 2.8 to 4.5.

Abstract: A chemical treatment method in which an object to be treated is treated with a chemical treating agent to form a chemical conversion coating, in which the object to be treated has at least one aluminum-plated steel sheet and at least one member selected from the group consisting of cold-rolled steel sheets, zinc-plated steel sheets, and aluminum sheets and the chemical treating agent is one which has zirconium, fluorine, and an aminated silane coupling agent and in which the zirconium content is 100-700 ppm in terms of metal amount and the fluorine/zirconium ratio is 3.5-7.0 by mole. A sufficient coating amount can be ensured on the surface of a zinc deposit, cold-rolled steel sheet, zinc-plated steel sheet, aluminum-plated steel sheet, or the like and a chemical conversion coating having sufficient base-hiding properties and sufficient adhesion can be formed.

Abstract: A solution for treating a surface of an iron material includes (a) zirconium fluoride; (b) ion of a rare earth element and/or a compound containing a rare earth element; (c) a polyallylamine; (d) aluminum ion; and (e) free fluorine ion. Zirconium in the component (a) is at a weight concentration A of 10 to 1000 ppm. The ratio K of the weight concentration B of the rare earth element in the component (b) to the weight concentration A (B/A) is 0.1 to 30. The component (d) is at a weight concentration D of 50 to 250 ppm. The component (e) is at a weight concentration E of 0.5 to 30 ppm. A coating having excellent corrosion resistance before and after the subsequent coating can be deposited on the surface of an iron material by using the surface treating solution which does not contain environmentally harmful ingredients.