Chromium-free solution for treating metal surfaces

摘要

An acidic chromium-free solution for treating a metal surface containing: (1) a vanadium cation source and/or a vanadyl cation source; (2) an organic acid as an anion source; and (3) at least one oxoacid as another anion source is provided. The oxoacid is selected from oxoacids of nitrogen, sulfur, phosphorus, boron, and chlorine. A metal component composed of, for example, aluminum or magnesium is brought into contact with the chromium-free solution to form a vanadium coating film of a surface of the metal component. A surface treating process using this chromium-free solution is useful for formation of a coating film having low corrosion resistance and low electric resistance.