Making superior corrosion resistant aluminum oxide films using ozone-electrochemical and electron microscopy studies

Abstract

Aluminum surfaces have been subjected to oxidation at 300 K, using a molecular beam of ozone of 97% purity. An enhancement of the kinetics of oxidation is found compared to oxidation by O2. The oxide film produced exhibits enhanced corrosion resistance as measured by several electrochemical methods compared to comparable thickness oxide films made by oxygen exposure. Transmission electron microscopy measurements show that the ozone-grown films exhibit small pore sizes and also increased average density as measured by the behavior of the radial distribution function derived from electron diffraction measurements on films made from ozone and oxygen. These effects may be due to the lower oxygen vacancy defect density in films made from ozone. The special properties of ozone-grown aluminum oxide films are preserved even after the films are removed from vacuum and exposed to the atmosphere.