Iron carbonate formation kinetics onto corroding and pre-filmed carbon steel surfaces in carbon dioxide corrosion environments

Abstract

This work investigates the Corrosion Layer Accumulation Rate (CLAR) of iron carbonate (FeCO3 onto X65 carbon steel in carbon dioxide containing environments using the direct method of corrosion layer mass gain measur ement. Glass cell experiments wer e per formed at 80 o C and pH 6.3 or 6.8 over a range of bulk FeCO3 saturation ratios using both actively corroding carbon steel and steel pre-filmed with FeCO3 The CLARs obtained from experiments using actively corroding samples displayed strong agreement with the most recently developed precipitation model by Sun and Nesic at high supersaturation for pH 6.3 and 6.8, but a disparity at low supersaturation for the solution at pH 6.8. The observed discrepancy was attributed to the significant difference in surface saturation ratio between the two conditions when the steel is actively corroding. CLARs determined for pre-FeCO3 filmed carbon steel show that the kinetics of FeC O3 formation reduce significantly once the film establishes a protective barr ier at lower values of supersaturation. The results highlight the contrast between surface layer accumulation kinetics in the early stages of growth and those encountered in the long-term after the development of a protective film.

Corrosion Protection through Naturally Occurring Films: New Insights from Iron Carbonate

“…A key impediment to the identification of drivers for such localized corrosion is the absence of studies focusing on the molecular structure and reactivity of naturally forming protective films, which are commonly referred to as corrosion scales. In the dissolved CO 2 regime, it is well-known − that these scales are composed of densely packed siderite (FeCO 3 ) crystallites (Figure ), but further details of these building blocks are scarce, despite being commonly observed in the recent literature. − Only in the past year has the habit, namely the characteristic external shape, of these FeCO 3 crystallites been explicitly described, and even then only qualitatively . In contrast to the anticipated rhombohedral geometry, a more complex 3D shape was reported, comprising a microfaceted cylinder with trigonal-pyramidal caps, as illustrated in the inset in Figure (b).…”

“…In the dissolved CO2 regime, it is well known [6][7][8] that these scales are composed of densely packed siderite (FeCO3) crystallites (Fig. 1), but further details of these building blocks are scarce, despite being observed widely in the recent literature [8][9][10][11] .…”

Conductive Polymer/SiO2 Composite as an Anticorrosive Coating Against Carbon Dioxide Corrosion of Mild Steel. A Simulation Study

“…A model of uniform carbon dioxide corrosion of mild steel (MS) has been developed by several researchers [1][2][3][4] in the form of electrochemical models for surface processes or semi-empirical correlations. A major issue for model development has been the effect of insoluble corrosion products on corrosion rate, for example, an iron carbonate [5]. The experimental investigations, in the case of studying the electrochemical behaviour of carbon dioxide corrosion, have been performed by numerous authors [6][7][8][9][10][11][12][13][14][15].…”

Effect of liquid flow velocity on corrosion behavior of 20# steel at initial stage under gas-liquid two-phase plug flow condition

“…Furthermore, whether the deposition pattern of corrosion products changes with the increasing liquid velocity and the mechanism of corrosion product film formation under actual service conditions remain unknown. Information about these aspects is also limited (Almeida et al , 2017; Kahyarian et al , 2017; Barkera et al , 2019).…”