Abstract: A coating composition is provided, the starting materials of which comprise nano SiO2, film-forming substance, film-forming aid, accelerator, acid, and water. The composition has pH of 3-9. A passivated zinc-plated material is also provided. The zinc-plated material comprises zinc-plated substrate and passivated coat adhered to the surface of the zinc-plated substrate, wherein the passivated coat is formed by curing the coating composition. The coating composition can impart to the zinc-plated material excellent corrosion resistance, water resistance, high temperature resistance, surface conductivity, and adhesion to the zinc-plated substrate. Additionally, the coating composition contains no Cr6+, and satisfies the requirement of EU RoHS Directive.

Abstract: The present invention provides a passivant for hot-dip Al—Zn-coated sheet of which the raw materials include: 2˜6 parts by weight of water soluble molybdate, 4˜12 parts by weight of water soluble manganese salt, 50˜100 parts by weight of basic silica sol and 50˜100 parts by weight of water soluble organic resin. The present invention also provides a method to prepare the passivant for hot-dip Al—Zn-coated sheet including the following steps: adding and dissolving water soluble molybdate and water soluble manganese salt into deionized water; adding basic silica sol into the solution and mixing well; adding water soluble organic resin into the solution and mixing well; regulating the pH value of the solution to 5˜8 by using phosphoric acid. The present invention also provides a hot-dip Al—Zn-coated sheet treated with the present passivant and a method to passivate hot-dip Al—Zn-coated sheet.

Abstract: A coating composition is provided, the starting materials of which comprise nano SiO2, film-forming substance, film-forming aid, accelerator, acid, and water. The composition has pH of 3-9. A passivated zinc-plated material is also provided. The zinc-plated material comprises zinc-plated substrate and passivated coat adhered to the surface of the zinc-plated substrate, wherein the passivated coat is formed by curing the coating composition. The coating composition can impart to the zinc-plated material excellent corrosion resistance, water resistance, high temperature resistance, surface conductivity, and adhesion to the zinc-plated substrate. Additionally, the coating composition contains no Cr6+, and satisfies the requirement of EU RoHS Directive.

Abstract: The invention provides a hot-dip galvanized steel plate with high adhesion between a plating layer and base steel, and belongs to the field of manufacturing hot-dip galvanized steel plates. Atomic concentration ratio Al/Zn of Al and Zn in a Fe-Al intermediate transition layer between a base steel and a plating layer of the hot-dip galvanized steel plate is 0.9-1.2. The plating layer did not have ? phase, but has relatively thin ? phase and little ? phase. The plating layer mostly consists of ? phase, thus obviously improving adhesion, scratch resistance and wear resistance of the plating layer.