passive state

in electrochemical corrosion
https://doi.org/10.1351/goldbook.P04447
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 [Terms] [Paper]