A Mechanistic Model for Carbon Dioxide Corrosion
of Mild Steel in the Presence of Protective Iron
Carbonate Films—Part 3: Film Growth Model |
by |
S. Nesic´, and K.-L.J. Lee** |
Abstract |
A model of iron carbonate (FeCO3) film growth is proposed, which is
an extension of the recent mechanistic model of carbon dioxide (CO2)
corrosion by Nesic, et al. In the present model, the film growth occurs
by precipitation of iron carbonate once saturation is exceeded. The
kinetics of precipitation is dependent on temperature and local species
concentrations that are calculated by solving the coupled species transport
equations. Precipitation tends to build up a layer of FeCO3 on the surface
of the steel and reduce the corrosion rate. On the other hand, the corrosion
process induces voids under the precipitated film, thus increasing the
porosity and leading to a higher corrosion rate. Depending on the environmental
parameters such as temperature, pH, CO2 partial |