Characterization of aluminum hydroxide thin film on metallic aluminum powder

Abstract

This article reports on the thickness and nature of the passivation film of industrial aluminum powders, which are of a great technological interest. These powders are used in the iron and steel industry as agents of reduction and pigment and as solid fuel of engines and rockets. Grain size was 9 μm. The XPS results enabled the determination of the thickness of the thin film, 35 Å, and to confirm the presence of aluminum hydroxide in the film, without indicating the type of aluminum hydroxide. The Raman spectrum revealed that the aluminum hydroxide of the passivation film was a bayerite. Only the infrared spectra allowed the characterization of both the nature and the presence of reactive sites on the powder: the passivation film was made up of bayerite containing surface groups of AlOH 2 1/2+ type. I emphasize, herein, the spectroscopic performance carried out for obtaining the infrared and Raman spectra of the thin film of a thickness less than 5 nm.