Corrosion Inhibition of Sodium Silicate with Nanosilica as Coating in Pre-Corroded Steel

https://doi.org/10.28991/cej-2021-03091761
Corrosion Coating Nanosilica Impedance Spectroscopy.

Authors

  • Marish S. Madlangbayan
    msmadlangbayan@up.edu.ph
    Department of Civil Engineering, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Carlo Nico B. Diola Department of Civil Engineering, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Alvin Karlo G. Tapia Institute of Mathematical Sciences and Physics, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Milagros M. Peralta Institute of Chemistry, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Engelbert K. Peralta Institute of Agricultural and Biosystems Engineering, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Ronaniel A. Almeda Institute of Agricultural and Biosystems Engineering, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Maris Asuncion L. Bayhon Institute of Agricultural and Biosystems Engineering, University of the Philippines Los Baños, Laguna 4031,, Philippines
  • Marloe B. Sundo Department of Civil Engineering, University of the Philippines Los Baños, Laguna 4031,, Philippines
Vol. 7 No. 11 (2021): November
Research Articles

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This study was conducted to investigate the potential of using sodium silicate with nanosilica as a treatment to inhibit the progress of corrosion in steel specimens that are already corroded. Steel specimens measuring 16 mm in diameter and 4 mm in thickness were prepared and subjected to pre-corrosion by immersion to 3.5% NaCl solution. Two sets of specimens were then dip-coated with sodium silicate containing nanosilica. One set was coated with 1% nanosilica, and the other was coated with 2.5% nanosilica. The coated specimens were then subjected to Complex Impedance Spectroscopy (CIS) at 20 Hz to 20 MHz frequency range. Compared with the sodium silicate coating with 1% nanosilica, the sodium silicate coating with 2.5% nanosilica had a larger semi-circle curve in the Nyquist plot. Similarly, the sodium silicate coating with 2.5% nanosilica also showed larger magnitudes of impedance at the low-frequency region and larger phase angles at the high-frequency regions in the Bode plot. These results imply that the sodium silicate coating with 2.5% nanosilica coating demonstrated better capacitive behavior. In addition, equivalent circuit modelling results also showed that the sodium silicate coating with 2.5% nanosilica had higher coating resistance and lower coating capacitance as compared to the sodium silicate coating with 1% nanosilica.

 

Doi: 10.28991/cej-2021-03091761

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