The effectiveness of the non-Fik diffusion model in the determination of water absorption rate of organic coatings.

Water diffusion in organic coatings was successfully measured in a study using EIS and wet cup methods.
water absorption and permeability are the key parameters for evaluating corrosion-resistant organic coatings.
these parameters can be easily estimated using electrochemical impedance spectrometrography (EIS

.
most defects and catastrophic damage caused by organic coatings are related to the transfer of water and accompanying contaminants to substrates through protective membranes.
although the diffusion of water in organic coatings is well known, there is a lack of experimental comparison between in-place electrochemical techniques and standard methods for measuring water absorption in self-reliant membranes.
continued immersion
in a recent study, 0.6 mol dm
-3
NaCl and 0.6 mol dm
-3Under the
condition
4
of 2
SO2, the corrosion resistance and water absorption rate of 4 commercial anti-corrosion organic coatings on galvanized steel were
. On-site EIS measurements.
the parameters related to water absorption with the permeability rate of water vapor in the self-supporting film measured by the wet cup method (ASTM-D1653).
consistent and appropriate method for studying water diffusion
found that when non-fico diffusion and coating swelling were taken into account, the EIS estimate of water permeability was only consistent with the wet cup method.
note that the presence and properties of two pollutants (CL
-
and SO4
2-
) do not significantly affect the penetration rate, but have a significant effect on the saturation time and swelling of water.
EIS and wet cup methods have been shown to be consistent and appropriate methods for studying water diffusion.
, however, eis provides a more detailed survey of water absorption and related degradation processes.
the study has been published
advances in organic coatings, volume 136, November 2019, 105206
.
.