Patent ID: 7452454

Claim:
A method of forming an second protective coating on a surface of an article having a first protective coating comprising an aluminum or aluminum alloy coating, said method comprising: A) providing an anodizing solution comprised of water and one or more additional components selected from the group consisting of: a) water-soluble complex fluorides, b) water-soluble complex oxyfluorides, c) water-dispersible complex fluorides, and d) water-dispersible complex oxyfluorides of elements selected from the group consisting of Ti, Zr, Hf, Sn, Al, Ge and B and mixtures thereof; B) providing a cathode in contact with said anodizing solution; C) placing an article having a first protective coating comprising aluminum or aluminum alloy on at least one surface of the article as an anode in said anodizing solution; and D) passing a current between the anode and cathode through said anodizing solution for a time effective to form a second protective coating on the at least one surface having the first protective coating.