Porous anodic oxides on titanium and on a Ti–W alloy

The growth of a nanoporous anodic oxide on titanium and a Ti–20 at.% W alloy, both deposited by magnetron sputtering, in a glycerol/phosphate electrolyte at 453 K is reported. The oxide formed on titanium is a mixture of amorphous titania and anatase. However, that on the alloy is amorphous only and forms at increased efficiency, about 27%. The amorphous structure is considered to be stabilized by incorporated units of WO3, which are distributed uniformly throughout the anodic film. The growth of the porous oxides is suggested to be associated with loss of film species at the film/electrolyte interface at the base of pores, with new oxide forming exclusively at the metal/film interface by inward migration of O2− ions.