The tin passivation in borate buffer was studied using potentiodynamic curves recorded at high scanning rate (9 V min-1, 3.6 V min-1). The most important feature of these curves is the presence of a current peak at around - 1180 mV (vs sce) which had not been previously observed. The nature of the passive film formed in the vicinity of this potential was characterized using in situ Mössbauer measurements. On the basis of these results it was concluded that in borate buffer solution: (a) the passive film formed at more negative range of potentials (- 1180 to - 780 mV) is duplex, consisting of highly amorphous Sn(OH)2 or hydrated stannous oxide and SnO2 or Sn(OH)4; (b) at more positive potentials, the passive layer consists only of Sn(IV) hydroxide or oxide which ensures a more efficient passivation.
ASJC Scopus subject areas
- Chemical Engineering(all)