TY - JOUR
T1 - Analysis of convective mass transfer by potential relaxation. IV. Active, prepassive, and transpassive iron dissolution at a rotating disk
AU - Pintauro, P. N.
AU - Roy, S.
PY - 1992/1
Y1 - 1992/1
N2 - Liquid-phase effective mass-transfer boundary-layer thicknesses and FeSO4 salt-film thicknesses were determined at an iron rotating disk in 2.OM H2SO4 by fitting short-time overpotential relaxation data after current interruption to a single mathematical model for surface concentration changes. Steady-state liquid-phase mass-transfer boundary-layer thicknesses during active and transpassive iron etching were in good agreement with those predicted by the Levich equation. Steady-state prepassive salt-film thicknesses, which varied between 0.0012 and 0.0039 cm, were found to be dependent on the disk rotation speed to the -0.57 power and the disk potential to the minus one-sixth power. For a short period of time during the initial stages of constant-current transpassive etching, a prepassive salt film was present on the iron surface. When this film dissolved, mass transfer was controlled by a liquid-phase boundary layer which was unaffected by moderate rates of O2 gas evolution. Salt films, which formed at particular current densities during steady-state transpassive iron etching, ranged in thickness from 0.0014 to 0.0016 cm and were independent of the applied potential and disk rotation speed.
AB - Liquid-phase effective mass-transfer boundary-layer thicknesses and FeSO4 salt-film thicknesses were determined at an iron rotating disk in 2.OM H2SO4 by fitting short-time overpotential relaxation data after current interruption to a single mathematical model for surface concentration changes. Steady-state liquid-phase mass-transfer boundary-layer thicknesses during active and transpassive iron etching were in good agreement with those predicted by the Levich equation. Steady-state prepassive salt-film thicknesses, which varied between 0.0012 and 0.0039 cm, were found to be dependent on the disk rotation speed to the -0.57 power and the disk potential to the minus one-sixth power. For a short period of time during the initial stages of constant-current transpassive etching, a prepassive salt film was present on the iron surface. When this film dissolved, mass transfer was controlled by a liquid-phase boundary layer which was unaffected by moderate rates of O2 gas evolution. Salt films, which formed at particular current densities during steady-state transpassive iron etching, ranged in thickness from 0.0014 to 0.0016 cm and were independent of the applied potential and disk rotation speed.
KW - convective mass transfer
KW - iron dissolution
UR - http://www.scopus.com/inward/record.url?scp=0026690186&partnerID=8YFLogxK
UR - https://iopscience.iop.org/article/10.1149/1.2069166
U2 - 10.1149/1.2069166
DO - 10.1149/1.2069166
M3 - Article
AN - SCOPUS:0026690186
SN - 0013-4651
VL - 139
SP - 177
EP - 186
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
IS - 1
ER -