The influence of halide ions on the passivity breakdown of carbon steel based on the point defect model

Research output: Contribution to report/book/conference proceedingsIn-proceedings paper

Authors

  • Elmira Ghanbari
  • Alireeza Saatchi
  • Danyil Kovalov
  • Bruno Kursten
  • Digby D. Macdonald

Institutes & Expert groups

  • University of California - Berkeley Etcheverry Hall

Abstract

An important factor in determining the breakdown of the barrier layer of the passive film on carbon steel in halide-containing solutions is the anion size. In this study, the influence of the size of aggressive anions on the passivity breakdown of UNS K02700 grade carbon steel exposed to saturated Ca(OH)2 solutions with the addition of different halides was investigated by using the potentiodynamic polarization (PDP) experiments. The PDP results were interpreted by using a mechanistic description based on the Point Defect Model (PDM). The experimental results revealed a linear dependence of the critical breakdown potential (Ec) on the logarithm of the activity of the breakdown-inducing halide (F-, Cl-, Br-, and I-), as predicted by the PDM. Furthermore, the PDM successfully accounted for the order with which the halides induce passivity breakdown, F- < Cl- > Br- > I-, in terms of competitive Gibbs free energy of anion dehydration and expansion of surface oxygen vacancies, into which the halide must absorb as the initial event in the breakdown process.

Details

Original languageEnglish
Title of host publicationNACE - International Corrosion Conference Series
PublisherNACE International
Pages1-8
Number of pages8
Edition2018
ISBN (Print)978-151086440-5
Publication statusPublished - 16 Apr 2018
Event2018 - CORROSION: Conference & Expo - Phoenix Convention Center, Phoenix, United States
Duration: 15 Apr 201819 Apr 2018
http://events.nace.org/WA/corrosion/c2018/index.html

Conference

Conference2018 - CORROSION
CountryUnited States
CityPhoenix
Period2018-04-152018-04-19
OtherCORROSION 2018 is the world’s largest corrosion conference and exposition. This comprehensive conference is packed with technical education and knowledge exchange, along with opportunities to connect with industry experts and peers focused on the prevention and mitigation of corrosion worldwide.
Internet address

Keywords

  • Passivity breakdown, Point defect model, Halide ion size

ID: 6893918