Electrochemical anodization, a method of obtaining highly-ordered porous oxides of various metal and alloys, has been studied for decades to elucidate the complicated formation mechanism. Both the widely supported field-assisted dissolution theory and the subsequently proposed field-assisted ejection theory suggest that porous oxide forms at the metal/oxide interface and is dissolved at the oxide/electrolyte interface. Here, in order to test this assertion, three-layered oxide films were fabricated on both Al and Ti foils. Both the inner and outer hemispherical bottoms vanish after the second anodization as they are covered by a new growth of oxide. The disappearance of both inner and outer hemispherical bottoms is evidence against the field-assisted dissolution and field-assisted ejection view that oxide grows only at the metal/oxide interface.

电化学阳极氧化是一种获得各种金属和合金的有序多孔氧化物的方法，数十年来一直在研究以阐明其复杂的形成机理。广泛支持的场辅助溶解理论和随后提出的场辅助喷射理论都表明，多孔氧化物在金属/氧化物界面形成并在氧化物/电解质界面溶解。在这里，为了测试这一断言，在铝箔和钛箔上都制作了三层氧化膜。第二次阳极氧化后，内部和外部半球形底部都消失了，因为它们被新的氧化物生长所覆盖。内部和外部半球形底部的消失是反对场辅助溶解和场辅助喷射观点的证据，即氧化物仅在金属/氧化物界面处生长。