Skip to Main Content
 

Global Search Box

 
 
 

ETD Abstract Container

Abstract Header

Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer

Di Bonaventura, Maria C.
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557

Abstract Details

2017, Master of Science (MS), Ohio University, Chemical Engineering (Engineering and Technology).
Iron carbonate (FeCO3) is the commonest corrosion product that forms on the surface of mild steel as a by-product of the CO2 corrosion process. This FeCO3 layer slows down further corrosion by acting as a diffusion barrier, blocking corrosive species from reaching the steel surface. However, high flow velocities, which can be common in various industrial operations, have been postulated either to lead to partial mechanical removal of FeCO3 layers or to impede the nucleation of FeCO3 crystals on the steel surface altogether. In the experimental study described herein, corrosion product formation in highly turbulent conditions was investigated with surface analysis techniques. Experiments were divided in relation to three different sets of tasks focusing on high initial saturation values, low and constant saturation values, and high velocity experiments. The first set of experiments was performed in a three electrode glass cell and rotating cylinder setup and investigated the presence/attachment/adherence of FeCO3 on the steel surface in short term experiments with high initial saturation values (S(FeCO3) = 150). The aim was to study the precipitation of FeCO3 in conditions where the bulk solution has a high concentration of ferrous ions at continuous rotational speeds, from the start to the end of each experiment. It was found that as the fluid velocity increased, there was less attachment of FeCO3, with the highest velocity of 2.0 m/s (wall shear stress of 7 Pa) showing no FeCO3 formation/attachment on the metal surface. The second task focused on controlling the pH and ferrous ion concentration in solution, in order to better mimic actual field conditions. Additionally, a controlled mass transfer setup was utilized that eliminated any non-uniformity of flow and centrifugal forces often associated with rotating cylinder working electrodes. In this set of experiments, four different materials and/or microstructures were tested, namely pure Fe (99.8%), UNS G10180 with two different microstructures (tempered martensite and ferritic-pearlitic), and API 5L X65. It was observed that the carbon content and microstructure (distribution of iron carbide [Fe3C]) have a strong effect on the results with the ferritic-pearlitic steel clearly favoring FeCO3 precipitation. The third task consisted of exposing the material tested to highly turbulent conditions in a Thin Channel Flow Cell (TCFC) to identify a critical velocity for removal of Fe3C. The material chosen displayed formation of FeCO3 in task 2, which was UNS G10180 with a ferritic-pearlitic microstructure. A critical velocity for Fe3C removal was clearly identified, which further inhibited formation of FeCO3, although it is fully expected that its value should depend on the operating conditions.
Marc Singer (Advisor)
Srdjan Nesic (Committee Member)
Reza M. Toufiq (Committee Member)
Craig Grimes (Committee Member)
207 p.
Chemical Engineering
CO2 corrosion; flow; shear stress; iron carbide; iron carbonate

Recommended Citations

Citations

  • Di Bonaventura, M. C. (2017). Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer [Master's thesis, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557

    APA Style (7th edition)

  • Di Bonaventura, Maria. Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer . 2017. Ohio University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557.

    MLA Style (8th edition)

  • Di Bonaventura, Maria. "Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer ." Master's thesis, Ohio University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557

    Chicago Manual of Style (17th edition)

ohiou1498849246022557
1,125
© 2017, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.