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Effect of seawater constituents on the performance of thermal spray aluminium (TSA) in marine environments

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journal contribution
posted on 27.03.2019, 10:12 by Rosa Grinon Echaniz, Shiladitya Paul, Rob Thornton
Thermally sprayed coatings are often used to mitigate corrosion of offshore structures. They act as a physical barrier to the aggressive marine environment and as a sacrificial distributed anode for low carbon steel. In such environments, the severity of material degradation depends on many factors. The effect of temperature, exposure time or the presence of microorganisms are the focus of many studies for example, however the effect of the different ions present in seawater remains largely unexplored. The chemical composition of the water changes considerably depending on the location; industrial, glacial, estuarine, etc. In addition, when Thermal Spray Aluminium (TSA) protects steel in seawater, calcareous matter precipitates as a result of the cathodic polarisation and subsequent localized increase in pH. Therefore, understanding how ions such as magnesium (II), calcium (II) or carbonates alter the coating properties in marine environment is important. This paper reports the experimental work carried out with TSA coated steel samples with defects in order to simulate mechanical damage or erosion of the coating. The combination of electrochemical tests and surface characterization provided evidence of the efficiency of the calcareous bilayer that forms on top of steel reducing the TSA degradation.

Funding

The authors gratefully acknowledge financial support from the Centre for Doctoral Training in Innovative Metal Processing (IMPaCT) funded by the UK Engineering and Physical Sciences Research Council (EPSRC), grant reference EP/L016206/1. This publication was made possible by the sponsorship and support of Lloyd’s Register Foundation, a charitable foundation helping to protect life and property by supporting engineering-related education, public engagement and the application of research. The work was enabled through, and undertaken at, the National Structural Integrity Research Centre (NSIRC), a postgraduate engineering facility for industry-led research into structural integrity established and managed by TWI through a network of both national and international Universities.

History

Citation

Materials and Corrosion / Werkstoffe und Korrosion, 2019, 70(6), pp. 996-1004

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Engineering

Version

VoR (Version of Record)

Published in

Materials and Corrosion / Werkstoffe und Korrosion

Publisher

Wiley, DECHEMA Gesellschaft für Chemische Technik und Biotechnologie e.V.

issn

1521-4176

Acceptance date

25/01/2019

Copyright date

2019

Available date

12/09/2019

Publisher version

https://onlinelibrary.wiley.com/doi/full/10.1002/maco.201810764

Language

en