Conditions for Transition From Barrier to Porous Oxidation of Aluminum in Phosphoric Acid Solutions

Substrate Purity Effect on the Defect Formation and Properties of Amorphous Anodic Barrier Al2O3

“…1,2 For instance, porous Al 2 O 3 is widely applied as a catalyst support because of its thermal stability and heat conductivity. [3][4][5][6][7] Dense and compact Al 2 O 3 layers (i.e. without porosity and thus, with a much lower specific surface area) are also of great industrial importance, particularly, for protective and decorative coatings.…”

“…Anodizing of metals and alloys in organic electrolytes of controlled pH (5)(6)(7), such as oxalic and citric acids, generally results in the formation of dense and low-defective barrier oxide layers with relatively low electrolyte impurity concentrations. 11,22,23 Nevertheless, the incorporation of minor impurity concentrations from the electrolyte solution into the grown Al 2 O 3 barrier layer seems unavoidable.…”