Abstract
Examination by ESCA of passivation films on tinplate has cast doubt on the assumptions sometimes made that only Cr°; is left after extraction of the films with boiling 5M NaOH, and that the sole action of anodic oxidation in phosphate solution is dissolution of Cr°. Therefore, methods of estimating Cr° content based on these assumptions give results in excess of true values. The amount of chromium insoluble in boiling 5M NaOH increases after a short time at raised temperature or after storage, and this effect was shown by ESCA to be due to dehydration of hydroxides.
Application of ESCA to fracture surfaces after detachment of lacquer showed that failure of adhesion occurred between the passivation film and the tin surface and that the growth of tin oxide could introduce a weak layer.
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