• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.396-412
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• 1997

The purpose of this study is to observe the corrosion characteristics of five dental amalgams(CAULK FINE CUT, OPTALLOY II, DISPERSALLOY, TYTIN, and VALIANT) in the solutions with fluoride compound through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylindrical metal mold, and condensed by hydraulic pressure(160 kg/$cm^2$). Each specimen was removed from the metal mold. Specimens were polished with the silicone carbide grinding paper 24 hours after condensation and stored at room temperature for 1 week. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgams in 0.9 % saline solution and in the saline solutions with 2.2 ppm, 0.05 %, 2 % NaF, and 8 % $SnF_2$ at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 30 minutes, the potential scan was begun. The potential scan range was -1500m V to + 800m V(vs. S.C.E.) in the working electrode and the scan rate was 50 mV/sec. The results were as follows, 1. The corrosion potential, the potential of anodic current peak, and transpassive potential in the saline solutions with NaF shifted to lower direction than those in normal saline solution, and the current density in the saline solutions with NaF was higher than that in normal saline solution. The differences were increased as the concentrations of NaF became higher. 2. The corrosion potential and transpassive potential in the saline solution with $SnF_2$ shifted to higher direction than those in normal saline solution, and the current density in the saline solution with $SnF_2$ was higher than that in normal saline solution after the corrosion potential. The anodic polarization curves in the saline solution with $SnF_2$ had no outstanding anodic current peak. 3. The corrosion potentials for high-copper amalgams were much higher than those for CAULK FINE CUT and OPTALLOY II in normal saline solution, but, as the concentrations of fluoride compound became higher, the differences in corrosion potentials between them were decreased. The corrosion potentials had the similarity in the saline solution with 2% NaF or 8% $SnF_2$. 4. The current density for TYTIN was the lowest among the others in normal saline solution and in the saline solution with 2.2 ppm or 0.05 % NaF. 5. There was no significant difference in current density between Pd-enriched VALIANT and other high-copper amalgams.

• International Journal of Concrete Structures and Materials
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• v.18 no.1E
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• pp.17-22
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• 2006

Artificial cracks were made in the cover concrete of specimens embedding ten types of steel rebars of different Cr contents. The research aims for developing Cr-bearing steel rebars resistant to macrocell corrosion environments induced by cracking in cover concrete. The cracks were subjected to intensive penetration of carbon dioxide (carbonation specimens) to form macrocells. The carbonation specimens were then treated with accelerated corrosion curing, during which current macrocell corrosion density was measured. The corrosion area and loss from corrosion were also measured at the end of 105 cycles of this accelerated curing. The results of the study showed that Cr-bearing steel with Cr content of 5% or more suppressed corrosion in a macrocell corrosion environment induced by the differences in the pH values due to carbonation of cracked parts. Cr-bearing steels with Cr content of 7% or more are proven to possess excellent corrosion resistance.

• Corrosion Science and Technology
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• v.22 no.5
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• pp.305-313
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• 2023

The objective of this study was to investigate the effectiveness of sodium dodecyl benzene sulfonate (SDBS) as a corrosion inhibitor on the pitting corrosion behavior of aluminum alloys used in electric vehicle battery cooling systems within a mixture of ethylene glycol and water (EG-W) coolant. Potentiodynamic polarization testing revealed unstable passive film formation on the aluminum alloys in the absence of SDBS. However, the addition of SDBS resulted in a robust passive film, enhancing the pitting corrosion resistance across all examined alloys. Pitting corrosion was predominantly observed near intermetallic compounds in the presence of Cl? ions, which was attributed to galvanic interactions. Among tested alloys, A1040 demonstrated superior resistance due to its lower areal fraction of precipitates and donor density. The incorporation of SDBS inhibitors mitigated the overall pitting corrosion process by hindering Cl? ion penetration. These findings suggest that SDBS can significantly improve pitting corrosion resistance in aluminum alloys employed in battery coolant environments.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.4
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• pp.265-270
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• 2002

Most of all the mechanical devices are becoming more high-speed and high-power as well as their used condition being more pollution with rapid development in industrial part. So, it is necessary for these devices to equip cooling system to overcome that kind of severe using condition. Industrial development and income increase causes rapid increase in using fossilenergy and it results in accelerating environmental pollution owing to the increasement in emission of air pollution substance. Specially, fresh water like stream and river water is acidified. Therefore, corrosion damage is accelerated in radiator for automobile that is using acidified water. So, in this study, corrosion test was carried out in distilled and tap water for the investigation on the corrosion behavior of Al-alloy that is using as material for radiator of automobile The main results obtained are as follows According to increase of temperature, open circuit potential is decreased in fresh water. And open circuit potential after deaeration is lower than that before deaeration. Corrosion current density in distilled water is less drained than that of tap water. And Corrosion current density after deaeration is less drained than that before deaeration.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.686-691
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• 2004

The present paper describes an experimental study on the corrosive behaviour of Rolling stock structures. It is important to predict corrosive behaviour of rolling stock structures for safe service and to know relation between corrosion and fatigue life. This paper practiced electrochemical corrosion test of SS400 and SM490A. This study will examine the corrosive properties and differences of SS400 and SM490A from measuring corrosion potential, corrosion current density and corrosion rate.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.11a
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• pp.188-190
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• 2001

We carried out to measure the variations of potential with current density polymers. The results were particularly examined to identify the influences on corrosion potential and corrosion rate of various factors including temperature and pH. The Tafel slope for anodic dissolution was determined by the polarization effect depending on these conditions. The optimum conditions were established for each case. The second anodic current density peak and maximum passive current density were designated as the relative corrosion sensitivity($I_{r}I_{f}$). The mass transfer coefficient value (${\alpha}$) was determined with the Tafel slope for anodic dissolution based on the polarization effect with optimum conditions.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.269-272
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• 2000

The flow accelerated galvanic corrosion characteristics of a carbon steel coupled to stainless steel were investigated in deaerated alkaline-chloride solutions as a function of flow velocities(0, 0.2, 0.4 and 0.6 m/s), pH(8, 9, and 10) and temperature(25, 50 and $75^{\circ}C$). The electrochemical properties of specimens were investigated by potentiodynamic test and galvanic corrosion test using RCE(Rotating Cylinder Electrode). Carbon steel did not show passive behavior in the alkaline-chloride solution. The galvanic current density increases with increasing flow velocity and temperature, but decreased with increasing pH. Flow velocity had a small effect on the galvanic current density at $25^{\circ}C$, whereas the flow velocity increased galvanic current density significantly at $50^{\circ}C$ and $75^{\circ}C$. This might be due to the increased solubility of magnetite at the higher temperature.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.3
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• pp.165-171
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• 2000

Experiments were carried out to measure variations in the oxidation potential and current density using the polarization curves of polycarbonate. The results were then examined to identify the influences affecting the oxidation potential related to various conditions, such as temperature, pH, and oxydase(citrate and lipase). The lines representing the active anodic and cathodic dissolution shifted only slightly in the potential direction relative to temperature, pH, and the effect of the enzyme. The Tafel slope for the anodic and cathodic dissolution was determined such that the reversibility polarization was indicated as being effected by various conditions. The slope of the polarization curves describing the active-to-passive transition region shifted noticeably in their direction. Also, by varying the conditions, the optimum conditions for the most ready transform were identified, including temperature, pH, oxidation rate, and resistance of oxidation potential. The critical oxidation sensitivity(I(sub)r/I(sub)f) of the anodic current density peak and maximum passive current density was also determined, which is used in measuring the critical corrosion sensitivity of a polycarbonate.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.4
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• pp.323-334
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• 2002

The purpose of this study is to investigate which current densities and etching times will result in an optimal etching depth and surface roughness when an Ni-Cr-Be alloy is etched with 30% perchloric acid($HClO_4$). For this study, observations were made by means of an optical three-dimensional surface roughness measuring machine and a scanning electron microscope. The etchings took place under the following conditions using current densities of $300mA/cm^2\;450mA/cm^2,\;600mA/cm^2$ and $750mA/cm^2$, and using etching time of three, five, six, seven and nine minutes. Under the conditions, the experiments reached the following conclusions. 1. When the current density is above $450mA/cm^2$ and the etching time is longer than five minutes, the etching depth increased as the current density and etching time increased. And the surface roughness was significantly influenced by the interaction of the current density and etching time. 2. Under the etching conditions of $600mA/cm^2$ and five minutes, the optimal etching depth for a resin cement space and the highest surface roughness for mechanical retention were obtained. The etching depth and surface roughness were $32.86{\mu}m$ and $7.90{\mu}m$, respectively. 3. Observations under the scanning electron microscope showed that both the corrosion at the grain boundary and the corrosion within the grain occurred on the etched surface. It was also observed that the corrosion at the grain boundary became more severe as the current density and etching time increased. In addition. at higher current densities and longer etching times general corrosion appeared.

• Corrosion Science and Technology
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• v.3 no.1
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• pp.34-38
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• 2004

The corrosion of reinforcement is a very important factor on the serviceability and safety of reinforced concrete structures. The corrosion rate influences directly the cover failure time of reinforced concrete structures because the corrosion rate is used to estimate the amount of corrosion and thus expansive pressure due to corrosion. In this study, several series of experiments are performed considering the chloride concentration in artificial pore solution. The potentials are measured according to the applied current density and then corrosion current densities are obtained from the Tafel plot for various chloride concentrations. The measured corrosion rates show good correlation with those of other researchers.