Surface treatment composition, surface treatment solution and surface treatment method for aluminium and its alloys

摘要

A highly uniform thin protective coating, with good appearance, anti-corrosion properties and adhesion properties, is provided by a surface treatment method wherein a surface treatment solution for aluminum and its alloys is prepared using a surface treatment composition for aluminum and its alloys comprising at least one type of phosphoric acid, condensed phosphoric acid or salt of these acids, at least one type of zirconium salt or titanium salt and effective fluoride, further comprising at least one type of phosphorous acid, hypophosphorous acid or salts of these acids, and this solution is brought in contact with the surface of an aluminum type metal.