Characterization of the oxide/hydroxide surface of aluminium using x-ray photoelectron spectroscopy: a procedure for curve fitting the O 1s core level

The performance of coated and bonded aluminium relies heavily upon its surface chemistry and hence characterization of the aluminium surface is important. A method to quantify the hydroxide concentration at aluminium oxide/hydroxide surfaces by curve fitting the O 1s peak is developed and tested in this paper. Pseudoboehmite, AlO(OH), is formed at the surface of aluminium after immersion in boiling water. The surface of this material was used to determine the binding energy of the unresolved O 1s component peaks that were referenced to the binding energy of the Al 2p oxide component. In vacuo heating resulted in changes in the elemental and functional composition that were consistent with dehydration of the pseudoboehmite. It is proposed that the resultant film comprises γ-alumina with residual hydroxide groups. The O 1s curve-fitting method was applied to air-formed films with known atmospheric exposure histories before and after heating in vacuo. The change in both the elemental composition and functional stoichiometry of the films upon heating was consistent with significant but incomplete dehydration. The probable surface phases are determined from the functional and elemental composition. Copyright © 2000 John Wiley & Sons, Ltd.