Formation of Environment Friendly Electrodeposition Films by CO2 Gas Dissolved in Seawater and Their Corrosion Resistance

Title & Authors
Formation of Environment Friendly Electrodeposition Films by CO2 Gas Dissolved in Seawater and Their Corrosion Resistance
Lee, Sung-Joon; Kim, Hye-Min; Lee, Seul-Gee; Moon, Kyung-Man; Lee, Myeong-Hoon;

Abstract
The peculiar feature of cathodic protection in seawater has the capability to form mineral calcareous deposits such as magnesium and calcium on metal surfaces. It is assumed that $\small{OH^-}$ ions are generated close to the metal surface as a result of cathodic protection and generated $\small{OH^-}$ ions increases the pH of the metal/seawater interface outlined as the following formulae. (1) $\small{O_2+2H_2O+4e{\rightarrow}4OH^-}$, or (2) $\small{2H_2O+2e{\rightarrow}H_2+2OH^-}$. And high pH causes precipitation of $\small{Mg(OH)_2}$ and $\small{CaCO_3}$ in accordance with the following formulae. (1) $\small{Mg^{2+}+2OH^-{\rightarrow}Mg(OH)_2}$, (2) $\small{Ca^{2+}+CO{_3}^{2-}{\rightarrow}CaCO_3}$. The focus of this study was to increase the amount of $\small{CO{_3}^{2-}}$ with the injection of $\small{CO_2}$ gas to the solution for accelerating process of the following formulae. (1) $\small{H_2O+CO_2{\rightarrow}H_2CO_3}$, (2) $\small{HCO^{3-}{\rightarrow}{H^+}+CO{_3}^{2-}}$. Electrodeposit films were formed by an electro-deposition technique on steel substrates in solutions of both natural seawater and natural seawater dissolved $\small{CO_2}$ gas with different current densities, over different time periods. The contents of films were investigated by scanning electron microscopy(SEM) and X-ray diffraction(XRD). The adhesion and corrosion resistance of the coating films were evaluated by anodic polarization. From an experimental result, only $\small{CaCO_3}$ were found in solution where injected $\small{CO_2}$ gas regardless of current density. In case of injecting the $\small{CO_2}$ gas, weight gain of electrodeposits films hugely increased and it had appropriate physical properties.
Keywords
Calcareous deposit films;$\small{Mg(OH)_2}$;$\small{CO_2}$ gas;$\small{CaCO_3}$;Cathodic protection;
Language
Korean
Cited by
References
1.
D. F. Hassonand, C. R. Corwe, Materials for Marine System and Structures, Vol. 28, Academic Press, (1998).

2.
W. H. Hartt, C. H. Culberson, S. W. Smith, Corrosion, 40 (1984) 609.

3.
C. Barchiche, C. Deslouis, D. Festy, O. Gil, V. Maillot, S. Touzain, B. Tribollet, "Characterization of Calcareous Deposits in Artificial Sea Water by Impedances Techniques : 3-deposit of $CaCO_3$ in the Presence $Mg^{2+}$", Electrochimica Acta, 48 (2003), 1645.

4.
S-H. Lin, S. C. Dexter, Corrosion, 44(9) (1988) 615.

5.
H. J. Ryu, M. H. Lee, Electro-deposit Formed by Mesh-Electrodeposition Technology on Steel Plate in Seawater and Their Corrosion Resistance (2000), 08.

6.
C. S. Lee, I. Y. Bae, K. J. Kim, K. M. Moon, M. H. Lee, J. Kor. Inst. Sur. Eng., 37 (2004) 253.

7.
M. H. Lee et al., "Adhesion and Corrosion Resistance of Magnesium Hydroxide Films Prepared by Application Principle of Cathodic Protection in Natural Seawater [Abstact]", Kor. Inst. Surf. Eng., (2012) 131.

8.
M. H. Lee, Environmentally Friendly Hybrid Coating Formed by Electro-deposition Method in Natural Seawater with Dissolved Carbon Dioxide. The 1st International Conference on Surface Engineering (ICSE 2013), (2013) 620.

9.
S. H. Lee, H. M. Kim, K. M. Lim, B. K. Kim, M. H. Lee, J. Korean Inst. Surf. Eng., 46 (2013) 1.