Structure of Hydrated Chromium Oxide Film on Tin Free Steel

Abstract

According to the determination of the thickness and weight of the hydrated chromium oxide film and electro-microbalance, respectivelly, the density of the film is estimated as 2.32 g/cm³. By using the chromium content (44.8%) and the amount of water (24%) in the film, the chemical formula for the film is considered to be 2CrOOH·3H₂O.
Five peaks are recognized at 3400, 1600, 1425, 910 and 530 cm⁻¹ in the infrared absorption spectra of the film.
From the above results, it may be assumed that the hydrated chromium oxide film on T.F.S. forms macro-molecules bonded with the OH bridge.