Making a Superior Oxide Corrosion Passivation Layer on Aluminum Using Ozone

Abstract

Aluminum oxidation by ozone produces an aluminum oxide layer which is superior in its corrosion properties compared to natural oxide, as measured by electrochemical methods. The electrochemically measured impedance of the O3-grown films is ∼10 times greater than that of O2-grown films of equivalent thickness. An enhanced pitting potential is observed for the O3-grown oxide film. Transmission electron microscopy results show that the pore size of O3-grown oxide films is considerably smaller than that of O2-grown films. Transmission electron microscopy electron diffraction studies show that the amorphous O3-grown films are ∼4% more dense than the O2-grown film. The initial sticking coefficient for ozone on atomically clean polycrystalline aluminum is 3.8 times larger than for oxygen at 300 K.