Mechanistic insights of dissolution and mechanical breakdown of FeCO3 corrosion films

TL;DR

This study investigates how pH and flow conditions affect the chemical composition and mechanical integrity of FeCO3 corrosion films on steel, revealing dissolution and damage mechanisms relevant for corrosion control.

Contribution

It combines molecular techniques and imaging to elucidate the effects of pH and flow on corrosion film formation, transformation, and breakdown on steel surfaces.

Findings

Corrosion products include siderite, wustite, and magnetite at neutral pH.

Low pH and flow cause significant dissolution and mechanical damage.

Flow facilitates removal of entire crystals at neutral pH.

Abstract

To understand the behavior of corrosion films on X65 C-steel under CO2 conditions is paramount to identify the formation and transformations of corrosion products. This work presents the chemical changes and mechanical effects produced by pH and flow on corrosion films through the combination of molecular techniques with imaging. Siderite, wustite and magnetite were identified as corrosion products at neutral pH, which dissolved and mechanical damaged at low pH by a 1m/s brine flow with a crystal size reduction of ~80%. In contrast, at pH 7 and 1m/s flow facilitated the removal of entire crystals from the film.