Structural characterization by SIMS of alumina coatings on stainless steel

Al2O3 coatings were obtained by the alkoxide route and deposited on stainle ss steel using the dip coating technique. The starting precursor was alumin um sec-butoxide modified by acrylic acid in order to prevent its precipitat ion in the presence of water. Useful information for the structural organization of alumina coatings on s tainless steel is deduced from SIMS analysis. SIMS data reveal that the coa ting structure brings into play two different layers: an outer alumina laye r that is more or less doped, mainly by iron, and an internal layer corresp onding to the alumina/steel interphase. Beneath the interphase, the presenc e of an oxidized steel layer on the substrate surface is detected. Whatever the coating, the alumina/steel interphase exhibits a nearly consta nt thickness. On the other hand, a thickness variation of the oxidized stee l layer is observed between samples under study: this thickness increases w ith the curing time of the coating.