Water Permeability of Rust Layer Formed by Atmospheric Corrosion
Transactions of the Iron and Steel Institute of Japan
Synopsis Waler /Jenneability oj rust la)'us Jormed on a carbon sled and a low allo)1 steel by atmospheric corrosion was evaluated by means if impedance measurement oj the ru sted specimen electrode in 0.1 J\![ sodium ben;:oale aqueous solution . R esistance oj rust layer decreases with immersion time as the solution penetrales into the rusl and finally altains a sleady slale. Inilial and final values oj lhe "esistance and also the time necessQ/:V to reach the sleady slate increase with
... rease with increasing oj the /Jeriod oj almospheric eX/Josure. These values are larger Jor the low all~y steel than lhose Jor the carbon sleel at lhe same exposure lime. A linear relationshi/J has been Jound between almos/Jheric corrosion rale and reci/Hocal oj lhe final resistances. The laUer provides a sort oj measure Jor the porosity oj rust la)'er. i n the case oj lhe low alloy sleellhe deviation oj the final values Jrom lhe linearity is Jound and lhe initial values come to agree wilh lhe line as exposure time becomes longer. i t is sU/Jposed that corrosion rale de/Jends on lhe lime oj welness which delermines how large is th e area oj the sleel surface where the waler reaches lhrough the porosilies and corrosion slarts.