Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer
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Ohio University / OhioLINK
2017
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-ohiou14988492460225572021-08-03T07:03:09Z Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer Di Bonaventura, Maria C. Chemical Engineering CO2 corrosion flow shear stress iron carbide iron carbonate 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 withthe 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. 2017-09-19 English text Ohio University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557 http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Chemical Engineering CO2 corrosion flow shear stress iron carbide iron carbonate |
| spellingShingle |
Chemical Engineering CO2 corrosion flow shear stress iron carbide iron carbonate Di Bonaventura, Maria C. Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer |
| author |
Di Bonaventura, Maria C. |
| author_facet |
Di Bonaventura, Maria C. |
| author_sort |
Di Bonaventura, Maria C. |
| title |
Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer |
| title_short |
Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer |
| title_full |
Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer |
| title_fullStr |
Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer |
| title_full_unstemmed |
Effect of Flow on the Formation of Iron Carbonate and Influence of Exposed Iron Carbide Layer |
| title_sort |
effect of flow on the formation of iron carbonate and influence of exposed iron carbide layer |
| publisher |
Ohio University / OhioLINK |
| publishDate |
2017 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1498849246022557 |
| work_keys_str_mv |
AT dibonaventuramariac effectofflowontheformationofironcarbonateandinfluenceofexposedironcarbidelayer |
| _version_ |
1719452449527300096 |