Adhesion and Corrosion Resistance of Mg(OH)2 Films Prepared by Application Principle of Cathodic Protection in Natural Seawater
천연해수 중 음극방식 응용 원리에 의해 제작한 Mg(OH)2 코팅막의 밀착성 및 내식성
이승효;김혜민;임경민;김병구;이명훈;
Lee, Seung-Hyo;Kim, Hye-Min;Lim, Kyung-Min;Kim, Byung-Gu;Lee, Myeong-Hoon;
한국해양대학교 기관공학부;
Division of Marine Engineering, Korea Maritime University;
DOI : 10.5695/JKISE.2013.46.1.001
Cathodic current on a metal tends to increase the $OH^-$ neighboring to the metal surface, especially during electro-deposition in seawater. The increased pH at metal/seawater interface results in precipitation of brucite crystal structure-$Mg(OH)_2$ as following formula; $Mg^{2+}+2OH^-{
ightarrow}Mg(OH)_2$, that is typical mechanism of the main calcareous deposits-compound in electro deposited coating films. In this study, the effects of anode and current density on deposition rate, composition structure and morphology of the deposited films were systematically investigated by scanning electron microscopy(SEM) and x-ray diffraction(XRD), respectively in order to overcome the problems such as deposition rate and a weak adhesion between deposit film and metal surface. The adhesion and corrosion resistance of the coating films were also evaluated by anodic polarization test. The electro-deposited film formed by using AZ31-Mg anode had the most appropriate physical properties. Weight gain of electro-deposit films increased with increasing cathodic current. Electro-deposit prepared at $5A/cm^2$ current density shows better adhesion than that formed at $8{sim}10A/cm^2$.
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