Dissolution of Stainless Steel in Artificial Saliva

Dissolution of stainless steel type 304 in artificial saliva was studied by electrochemical methods, electron spectroscopy for chemical analysis, 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 to be 25 ± 3 A, independent of the potential. The passive film consists of a duplex structure: an inner laye r of (Cr0.5Fe0.5)xO3 and an outer layer of a mixture of Cr(OH)3 and (CrxFey)PO4.2H2O. The analysis indicated that 1 1 ug/cm2 of the alloying elements were disollved during exposure for 1 year.