The passive state is characterized by a contiguous '
passivating film' of solid
corrosion products separating the metallic phase from the adjacent electrolyte.
Corrosion in the passive state involves growth of the passivating
film and/or transfer of metal ions through the
film into the electrolyte.
Source:
PAC, 1989, 61, 19
(Electrochemical corrosion nomenclature (Recommendations 1988))
on page 21