• Clean Technology
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• v.15 no.4
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• pp.239-244
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• 2009

$Mg(OH)_2$ slurry was prepared by using natural mineral brucite mined in Liaoning province in China, and its de-$SO_x$ efficiency was compared with that of $Mg(OH)_2$ slurry prepared by thermal decomposition and hydration of magnesite. The physical and chemical characteristics of $Mg(OH)_2$ Powders prepared from brucite and magnesite were similar. However, the layered plate structure of $Mg(OH)_2$ crystal particles prepared from brucite had grown more stably. The desulfurization efficiency of $Mg(OH)_2$ slurry prepared from brucite was slightly higher than that of magnesite. Brucite may be used as a new absorbent for the desulfurization of flue gas in the future.

• Clean Technology
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• v.16 no.4
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• pp.254-257
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• 2010

[ $Mg(OH)_2$ ]slurry was prepared by using natural mineral brucite exploited from Liaoning province in China, and its de-SOx efficiency was examined. The effect of difference in particle size distribution of brucite and activation by hydrothermal treatment were investigated. The de-$SO_2$ efficiency of a finely-milled brucite sample below 1000 mesh with narrow particle size distribution was higher than that of the sample below 80 mesh. On the other hand, the de-$SO_2$ efficiency of brucite sample below 80 meshes was significantly improved by the hydrothermal treatment at 363 K tor 3 h.

• Journal of the Korean institute of surface engineering
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• v.37 no.5
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• pp.253-262
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• 2004

Calcareous deposits are the consequence of pH increase of the electrolyte adjacent to metal surface affected by cathodic current in seawater. It obviously has several advantages over conventional coatings, since the calcareous deposit coating is formed from coating (Mg$^{2+}$, $Ca^{2+}$) naturally existing in seawater. In consideration of this respect, environment friendly calcareous deposit films were formed by an electro deposition technique on steel substrates submerged in 48$^{\circ}C$ natural seawater. And the influence of current density, coating time and attachment of steel mesh on composition ratio, structure and morphology of the electrodeposited films were investigated by Scanning Electron Microscopy(SEM), Energy Dispersive Spectroscopy(EDS) and X-Ray Diffractor(XRD), respectively. Accordingly, this study provides a better understanding of the composition between the growth of $Mg(OH)_2$ and $CaCO_3$ during the formation of electro deposit films on steel substrate under cathodically electrodeposition in $48^{\circ}C$ natural seawater. The Mg compositions, in general, are getting decreased regardless of current density but Ca compositions are getting increased as electrodeposition time runs. That is, $Mg(OH)_2$ compounds of brucite structure shaped as flat type is formed at the initial stage of electrodeposition, but CaCO$_3$ compounds of aragonite structure shaped as flower type is formed in large scale. Besides, $Mg(OH)_2$ compounds were much formed at 5 A/$\m^2$ environment condition compared to the 3 A/$\m^2$ and 4 A/$\m^2$ environment conditions. This is because that OH- which was comparatively largely generated at the metal surface is preferably combined with $Mg^{2+}$TEX>.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.191-191
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• 2015

해수에 침지되어 있는 금속에 음극방식법을 실시하게 되면 $OH^-$이온이 증가하게 된다. 이때 금속기판과 용액의 계면에서 pH는 상승하고, 석출하는 피막에 영향을 준다. 표면에 형성되는 피막은 주로 부르사이트(Brucite)이고, 이는 전기화학방식의 전형적인 석회질 피막(Calcareous Deposits Film)형성 메커니즘을 따른다. 본 연구에서는 음극에 흘려주는 전류밀도 및 양극의 영향을 분석하였으며 SEM, XRD, EDS를 이용하여 피막의 조성성분과 결정구조를 확인했다. 전착피막의 내식성은 AZ31-Mg 양극 사용 시 가장 우수하였고, 전류밀도는 $1{\sim}10A/m^2$중 $5A/m^2$에서 가장 우수한 밀착력을 보였다. 따라서 위와 같은 코팅 제작 프로세스에 대한 기초적인 설계 지침을 제시함으로서 천연코팅막의 한계를 보완 할 수 있을 것이라 사료된다.

• Journal of the Korean institute of surface engineering
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• v.46 no.1
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• pp.1-8
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• 2013

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; $Mg^{2+}+2OH^-{\rightarrow}Mg(OH)_2$, 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 $8{\sim}10A/cm^2$.