ATMOSPHERIC CORROSION OF Al-OXYHYDROXIDE FILMS BY NaCl DROPLETS

摘要

Atmospheric corrosion due to adsorption of water and solutes onto metal and metal-oxide surfaces is a critical factor in the long-term reliability of electronic devices. Boehmite, an Al-oxyhydroxide [γ-AlO(OH)], is one of several aluminum oxides, oxyhydroxides and hydroxides that can form during the oxidation of aluminum and has been observed in the passive thin films protecting Al metal and Al-metal alloys from further oxidation and corrosion. Despite the protection of a thin oxide film, the exposure of Al-metal to halides such as chloride (Cl~-) results in pitting corrosion. The objectives of this research are to (1) establish the preferred sites of Cl~- adsorption on the boehmite surface and (2) determine the diffusion rate of Cl~- along the surface. The preferred sites of Cl~- adsorption will be important in determining where Al-metal pit formation is initiated and the diffusion rate of Cl~- along the oxide surface may be a rate-limiting factor in pit growth.