Author : Xin Gao
Publisher :
ISBN 13 :
Total Pages : 191 pages
Book Rating : 4.:/5 (12 download)
Book Synopsis Localized Corrosion Initiation of Steel in CO2 Environments by : Xin Gao
Download or read book Localized Corrosion Initiation of Steel in CO2 Environments written by Xin Gao and published by . This book was released on 2020 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this dissertation research was to investigate initiation mechanisms for CO2 localized corrosion on mild steel, encompassing the effects of chloride, oxygen, and acetic acid. In CO2 corrosion, iron in steel will be oxidized to ferrous ions under deareated conditions. The ferrous and carbonate ions can combine to form FeCO3 and precipitate once exceeding the solubility limit. When the precipitation of FeCO3 occurs evenly on the steel surface it forms a compact and protective layer. This acts as a diffusion barrier hindering the mass transfer of electrochemical species and covers/blocks the surface making it unavailable for corrosion, which enhances the resistance of mild steel to further uniform CO2 corrosion. However, there are various scenarios where localized corrosion may occur. When the environment becomes more aggressive, the FeCO3 could be partially removed. This leads to localized regions of the bare steel surface that become exposed to the corrosive solution and, subsequently, localized corrosion could be initiated. To study CO2 localized corrosion, two-stage experiments were performed: (1) a uniform protective FeCO3 layer was first formed on a carbon steel with high initial FeCO3 saturation; (2) localized CO2 corrosion scenarios were then developed by adding additional salts (NaCl or NaClO4), oxygen or acetic acid to challenge the protective FeCO3 layer. The experiments were conducted in a two-liter glass cell with a three-electrode system, working electrode (X65 carbon steel), reference electrode (Ag/AgCl saturated electrode), and counter electrode (platinum). Electrochemical measurements (linear polarization resistance) were carried out to observe electrochemical behaviors and calculate the corrosion rates.