• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.918-923
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• 2007

Fuel cell is a modular, high efficient and environmentally energy conversion device, it has become a promising option to replace the conventional fossil fuel based electric power plants. The high temperature fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. Corrosions in molten electrolytes and the electric conductivity across the oxide scale have crucial characteristics. When molten salts are involved, high temperature corrosions become severe. In this sense, corrosions of alloys with molten carbonates have the most severe material problems. Systematic investigation on corrosion behavior of Fe/21Cr/Ti or Al alloy has been done in (62+38)mol% (Li+K)$CO_3$ melt at $650^{\circ}C$ using the electrochemical impedance spectroscopy method. It was found that the corrosion current of these Fe-based alloys decreased with increasing Al or Ti. And Al addition improved the corrosion resistance of this type of specimen and more improvement of corrosion resistance was observed at the specimen added with Al.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.118-127
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• 2012

TiN or Ti/TiN was coated on stainless steel as bipolar plate in polymer electrolyte membrane fuel cells (PEMFCs) to improve their corrosion resistance and electric conductivity, and their properties were examined under fuel cell operating condition. After 200 hours operation, the behaviors for the corrosion, crack and dissolution of coating layer were investigated by various techniques. The corrosion and exfoliation of coating layer were considerably generated except for SUS316L-Ti/TiN after fuel cell operation even if the electric conductivity and corrosion resistance of coated stainless steel bipolar plates were improved. The adoption of Ti layer between TiN layer and the surface of stainless steel enhanced the adhesion of TiN layer and decreased the possibility of corrosion by the increase of coating layer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.67-75
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• 1993

This study was performed for the purpose of estimating steel corrosion and of considering a countermeasure to prevent steel corrosion of concrete structures under the environment of seawater or using seasand. The corrosion of steel was accelerated in artificial seawater with seven kinds of specimen which was embedded steel in mortar. To assume the degree of steel corrosion, soluble chloride content in mortar, $Cl^-$ binding capacity, half cell potential and corrosion area ratio were measured. The results show that corrosion area ratio was correlative with half cell potential and soluble chloride content in mortar.

• Corrosion Science and Technology
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• v.10 no.2
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• pp.71-75
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• 2011

Corrosion properties of Al-0.3Ga-0.3Sn, Al-0.3Mn-0.3Ga, and Al-0.3Mn-0.3Sn alloys were examined to develop an anode material for Al-air battery with alkaline aqueous or ethanol electrolyte. The results of potentiodynamic polarization tests showed that the electrode potential of the Al alloys were lower than the pure Al, implying the cell voltage can be increased by using one of these alloys for an anode in 4 M KOH aqueous solution. The corrosion rate appeared to be increased by alloying Ga but to be reduced by Sn and Mn in the aqueous solution. The ethanol solution is expected to improve the cell performance in that the electrode potential and the corrosion rate of Al were lower in ethanol solution than in aqueous solution. However the Al-(Ga, Sn, Mn) alloys are not favorable in ethanol solution because of the high potential and corrosion rate.

• Journal of the Korean institute of surface engineering
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• v.40 no.2
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• pp.82-90
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• 2007

Crevice corrosion is the accelerated attack occurred in the occluded cell under a crevice on the metal surface. Crevice corrosion behaviors of nickel-based alloys such as Alloy 600 and Alloy 690 were investigated in acidic solution with different chloride ion concentrations. Tests were carried out using the specially designed crevice cell with a very narrow Luggin capillary assembly to measure the potential inside the crevice. It is believed that crevice corrosion in active/passive system like nickel-based alloys has much to do with the properties of passive film and its repassivation characteristics, investigated by the capacitance measurement and by the abrading electrode technique, respectively. An attempt was made to elucidate the relationship between crevice corrosion behaviors, properties of passive film and its repassivation kinetics. Results showed that repassivation rate parameter $n1{\leq}0.6$ and/or $n2{\leq}0.5$ indicated the possible occurrence of crevice corrosion.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.113-120
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• 2017

HCP(Half Cell Potential) method has been widely used since it is recognized as a efficient NDT(Non Destructive Technique) for corrosion detection. This work is for an evaluation of relation between corrosion amount and measured HCP in dried condition through ICM(Impressed Current Method) for accelerating corrosion. For the work, cement mortar specimens with three w/c ratios and four cover depths are prepared, and corrosion test based on ICM is performed for 6 hours, 18 hour, and 42 hours with constant 20V of electrical charge, respectively. From the test, corrosion amount increases with reduced cover depth, increasing w/c ratio, and extended corrosion period, where corrosion amount is evaluated to linearly increases with measured HCP in dried condition. In order to evaluate corrosion amount through measured HCP, the measured HCP level is firstly determined and then corrosion amount is to be compared with measured HCP, which is evaluated to be more reasonable with higher C.O.V.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.69-75
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• 2008

Electrochemical behaviors of surface modified and MC3T3-E1 cell cultured Ti-30Ta alloys have been investigated using various electrochemical methods. The Ti alloys containing Ta were melted by using a vacuum furnace and then homogenized for 6 hrs at $1000^{\circ}C$. MC3T3-E1 cell culture was performed with MC3T3-E1 mouse osteoblasts for 2 days. The microstructures and corrosion resistance were measured using FE-SEM, XRD, EIS and potentiodynamic test in artificial saliva solution at $36.5{\pm}1^{\circ}C$. Ti-Ta alloy showed the martensite structure of ${\alpha}+{\beta}$ phase and micro-structure was changed from lamellar structure to needle-like structure as Ta content increased. Corrosion resistance increased as Ta content increased. Corrosion resistance of cell cultured Ti-Ta alloy increased predominantly in compared with non cell cultured Ti- Ta alloy due to inhibition of the dissolution of metal ion by covered cell. $R_p$ value of MC3T3-E1 cell cultured Ti-40 Ta alloy showed $1.60{\times}10^6{\Omega}cm^2$ which was higher than those of other Ti alloy. Polarization resistance of cell-cultured Ti-Ta alloy increased in compared with non-cell cultured Ti alloy.

• Corrosion Science and Technology
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• v.3 no.5
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• pp.187-193
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• 2004

We have investigated the differences between the general corrosion and microbiologically influenced corrosion (MIC) of steels in terms of electrochemical behavior and surface phenomena. Corrosion potential of steels in the absence of SRB (sulfate-reducing bacteria) shifted to a low level and was maintained throughout the experimental period (40 days). The potential in the presence of SRB, however, shifted to a noble level after 20 days' incubation, indicating the growth of SRB biofilms on the test metal specimens and a formation of corrosion products. In addition, the color of medium inoculated with SRB changed from gray to black. The color change appeared to be caused by the formation of pyrites (FeS) as a corrosion product while no significant color change was observed in the medium without SRB inoculation. Moreover, corrosion rates of various steels tested for MIC were higher than those in the absence of SRB. This is probably because SRB were associated with the increasing corrosion rates through increasing cathodic reactions which caused reduction of sulfate to sulfide as well as formation of an oxygen concentration cell. The pitting corrosions were also observed in the SRB-inoculated medium.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.73-78
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• 1993

This study was performed for the purposes of estimating steel corrosion of concrete structures under the environment of seawater. The corrosion of steel was accelerated in artificial seawater with seven kinds of specimen which was embedded in mortar. By measuring choride content in mortar, half cell potential and corrosion area ratio, the degree of steel corrosion can be assumed.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.197-202
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• 1998

The corrosion of steel reinforcements in concrete is of much concern in recent years. The mechanism of corrosion, however, is not clear yet. This study is focused on the corrosion of steel induced by internal chlorides in concrete at early ages. To examine the critical concentration of steel, half-cell potential, chemical composition of expressed pore solutions of mortars and rate of corrosion area were observed with respect to additions of chlorides, types of binders, water-binders ratio.