DISSOLUTION OF STAINLESS-STEEL IN ARTIFICIAL SALIVA

Dissolution of stainless steel type 304 in artificial saliva was studi ed by electrochemical methods, electron spectroscopy for chemical anal ysis, and atom absorption spectroscopy. The samples were polarized in the -400 mV (saturated calomel electrode) to -50 mV (saturated calomel electrode) range. The total thickness of the passive film was found t o be 25 +/- 3 Angstrom, independent of the potential. The passive film consists of a duplex structure: an inner layer of (Cr0.5Fe0.5)(2)O-3 and an outer layer of a mixture of Cr(OH)(3) and (CrxFey)PO4 . 2H(2)O. The analysis indicated that 11 mu g/cm(2) of the alloying elements we re dissolved during exposure for 1 year.