Barrier and Sacrificial Protection Mechanisms of Zinc Rich Primers

  • Mohsen Saeedikhani National University of Singapore
  • Sudesh L. Wijesinghe National University of Singapore
  • Daniel John Blackwood National University of Singapore

Abstract

A specific type of Zinc-Rich Paint was scratched and exposed in salt fog chamber for various exposure times up to 1,000 hours. The corrosion products that developed within the scratched region were studied by optical microscopy, scanning electron microscopy, and Electrochemical Impedance Spectroscopy (EIS). Bode plots were used to obtain the total resistance of the coating by salt spray exposure time. The results suggest that the mechanism of protection of zinc rich paints may not be simply as only sacrificial action followed by only barrier action, but rather an iteration of these two mechanisms exist. Although at very short times, prior to deposition of zinc corrosion products in the scratch, sacrificial action is the only mechanism of protection, once the corrosion products start to form there is a conjunction of the two protection actions with one dominating from time to time. This dual protection mechanism continues until all the available free zinc within the throwing power distance of the scratch has been consumed, at which point only barrier protection remains in action.

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Author Biographies

Mohsen Saeedikhani

Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576

Sudesh L. Wijesinghe

Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576

Measurements and Characterization Unit, Singapore Institute of Manufacturing Technology, A*STAR, Singapore 138634

Daniel John Blackwood

Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576

Published In
Vol 23 No 4, Aug 8, 2019
How to Cite
[1]
M. Saeedikhani, S. L. Wijesinghe, and D. J. Blackwood, “Barrier and Sacrificial Protection Mechanisms of Zinc Rich Primers”, Eng. J., vol. 23, no. 4, pp. 223-233, Aug. 2019.