Abstract

The present invention is directed to a process for forming a well visible non-chromate conversion coating on surfaces of magnesium and magnesium alloys, to a composition therefor and to a method of use for such coated articles having surfaces of magnesium or any magnesium alloy. The composition is a solution or dispersion comprising a fluorosilicon acid. The composition is preferably an aqueous solution having a pH in the range from 0.5 to 5 and includes often at least one pH adjustment agent. The thereof formed coating is useful to increase the corrosion resistance and the adhesion of magnesium and magnesium alloys to a paint coating, powder coating, e-coat, fluoropolymer coating, self-lubricant layer and adhesive bonding layer. The conversion coating may favorably be coated with a fluoropolymer coating, coated with a silane based sealing or both. The such formed coating is typically of grey mat non-metallic appearance.

IPC Classes  ?

• B05D 1/18 - Processes for applying liquids or other fluent materials performed by dipping

Abstract

A method of treating metallic workpieces with an anodizing solution, compositions of the anodizing solution and the coatings prepared with this anodizing solution for anodizing metallic surfaces, especially surfaces of magnesium, magnesium alloys, aluminum and aluminum alloys, are disclosed. The compositions are basic aqueous solutions comprising a water-soluble inorganic hydroxide, phosphorus and oxygen containing anions, at least one surfactant and an alkaline buffer based on at least one alkaline hydrolyzed silane, on at least one alcohol showing at least one alkaline radical group or on a mixture of them.

IPC Classes  ?

• C25D 11/02 - Anodisation
• C25D 11/18 - After-treatment, e.g. pore-sealing
• C25D 11/30 - Anodisation of magnesium or alloys based thereon