Formation of Environment Friendly Electrodeposition Films by CO2Gas Dissolved in Seawater and Their Corrosion Resistance
해수 중 CO2기체의 유입에 의한 환경 친화적인 전착 코팅막의 형성과 그 내식특성

Sung-Joon Lee, Hye-Min Kim, Seul-Gee Lee, Kyung-Man Moon, Myeong-Hoon Lee
2014 Journal of the Korean institute of surface engineering  
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 OH − ions are generated close to the metal surface as a result of cathodic protection and generated OH − ions increases the pH of the metal/seawater interface outlined as the following formulae. (1) O 2 + 2H 2 O + 4e → 4OH − , or (2) 2H 2 O + 2e →H 2 + 2OH − . And high pH causes precipitation of Mg(OH) 2 and CaCO 3 in
more » ... H) 2 and CaCO 3 in accordance with the following formulae. (1) Mg 2+ + 2OH − →Mg(OH) 2 , (2) Ca 2+ + CO 3 2− →CaCO 3 . The focus of this study was to increase the amount of CO 3 2− with the injection of CO 2 gas to the solution for accelerating process of the following formulae. (1) H 2 O + CO 2 →H 2 CO 3 , (2) HCO 3− → 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 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 CaCO 3 were found in solution where injected CO 2 gas regardless of current density. In case of injecting the CO 2 gas, weight gain of electrodeposits films hugely increased and it had appropriate physical properties.
doi:10.5695/jkise.2014.47.1.039 fatcat:lhltgfvycrbrdmzuoffpirkh6i