• Journal of Fisheries and Marine Sciences Education
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• v.15 no.2
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• pp.176-183
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• 2003

Recently, with the tendency of lightening, high-strength and high-speed in the marine industries such as marine structures, ships and propellers, it is rapidly enlarged the use of the aluminium alloy. Therefore, there occurs much interest in the study on corrosion characteristics of aluminium alloy. This paper was studied on the corrosion characteristics of Al-Mg alloy propeller used for a coasting vessel. Under the various pH of marine environment, the corrosion test of Al-Mg alloy was carried out. And thus polarization resistance, corrosion potential, and current density behavior of Al-Mg alloy and galvanic corrosion behavior of Al-brass and Al-Mg alloy coupled Al 5086 and SS 400 for hull were investigated. The main results are as following: 1. The corrosion potential of Al-brass propeller is more nobel than materials for hull, but that of Al-Mg alloy propeller is low or similar to materials for hull. Therefore, the galvanic corrosion of hull due to Al-Mg propeller don't occur. 2. The polarization resistance of Al-Mg alloy in sea water of pH 4 is highest, and corrosion current density of Al-Mg propeller is the most controlled. 3. As pH value decreases, potential showed Evans polarization diagram approaches cathodic potential. The corrosion current density of Al-Mg alloy is controlled to anodic reaction rate, therefore, the corrosion reaction of Al-Mg alloy is anodic control.

• Journal of Surface Science and Engineering
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• v.39 no.1
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• pp.25-34
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• 2006

Al-Mg alloy, an open rack vaporizer(ORV) material was reported to be corroded in seawater environments though the ORV material was coupled to thermally sprayed Al-Zn alloy functioning a sacrificial anode. In addition, the corrosion behavior based on the calculated corrosion potential did not match the observed corrosion behavior. Hence, the goal of this study is to get better understanding on Al or Al-Mg alloy coupled to Al-Zn alloy and to provide the calculated corrosion potential representing the corrosion behavior of the ORV material by immersion test, electrochemical tests, and calculation of corrosion and galvanic potential. The corrosion potentials of Al and Al alloys also depended on alloying element as well as surface defects. The corrosion potentials of Al and Al-Mg alloy were changed with time. In the meantime, the corrosion potentials of Al-Zn alloys were not. The corrosion rates of Al-Zn alloys were exponentially increased with zinc contents. The phenomena were explained with the stability of passive film proved by passive current density depending on pH and confirmed by the model proposed by McCafferty. Dissimilar material crevice corrosion (DMCC) test shows that higher content of zinc caused Al-Mg alloy corroded more rapidly, which was due to the fact that higher corrosion rate of Al-Zn makes [$H^+$] and [$Cl^-$] more concentrated within pit solution to corrode Al-Mg alloy. Considering electrochemical reactions within pit as well as bulk in the calculation gives better prediction on the corrosion behavior of Al and Al-Mg alloy as well as the capability of Al-Zn alloy for corrosion protection.

• Korean Journal of Materials Research
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• v.19 no.3
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• pp.174-178
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• 2009

The effects of post-CMP cleaning on the chemical and galvanic corrosion of copper (Cu) and titanium (Ti) were studied in patterned silicon (Si) wafers. First, variation of the corrosion rate was investigated as a function of the concentration of citric acid that was included in both the CMP slurry and the post-CMP solution. The open circuit potential (OCP) of Cu decreased as the citric acid concentration increased. In contrast with Cu, the OCP of titanium (Ti) increased as this concentration increased. The gap in the OCP between Cu and Ti increased as citric acid concentration increased, which increased the galvanic corrosion rate between Cu and Ti. The corrosion rates of Cu showed a linear relationship with the concentrations of citric acid. Second, the effect of Triton X-$100^{(R)}$, a nonionic surfactant, in a post-CMP solution on the electrochemical characteristics of the specimens was also investigated. The OCP of Cu decreased as the surfactant concentration increased. In contrast with Cu, the OCP of Ti increased greatly as this concentration increased. Given that Triton X-$100^{(R)}$ changes its micelle structure according to its concentration in the solution, the corrosion rate of each concentration was tested.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.85-97
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• 2000

The purpose of this study was to compare the corrosion characteristics between implant fixture and two types of abutment screw ; gold screw, titanium screw. The anodic polarization behavior, the galvanic corrosion behavior, and the crevice corrosion behavior of prepared samples were investigated using potentiostat and scanning electron microscope. The results were as follows: 1. Anodic polarization behavior of samples; The primary passivation potential of implant fixture was -420mV, implant abutment was -560mV. titanium screw was -370mV and gold screw was -230mV. All samples were shown to have a high corrosion potential and good formation of passive film. The critical passive current density of gold screw was higher than that of other samples and the sample of gold screw showed a unstable passive film formation at passive region. 2. Galvanic corrosion behavior of samples; Contact current density between implant fixture and titanium screw showed $8.023{\times}10^{-5}C/cm^2$. Contact current density between implant fixture and gold screw showed $5.142{\times}10^{-5}C/cm^2$. 3. Crevice corrosion behavior of samples; The crevice corrosion resistance of sample using titanium screw was higher than that of sample using gold screw, and a severe corrosion morphologies were observed at the fixture-screw interface by the scanning electron microscope.

• Journal of Welding and Joining
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• v.18 no.3
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• pp.97-105
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• 2000

The stress corrosion cracking(SCC) and hydrogen embrittlement cracking(HEC) characteristics of a weathering steel weldment were investigated in aerated acid-chloride solution. The electrochemical properties of weldment were investigated by polarization test and galvanic corrosion test. Weathering steel did not show passive behavior in the acid-chloride solution. Galvanic corrosion between the weld metal and the base metal was not observed because the base metal was anodic to the weld metal. The slow-strain-rate tests(SSRT0 were conducted at a constant strain rate o 7.87×{TEX}$10^{-7}${/TEX}/s at corrosion potential, and at potentiostatically controlled anodic and cathodic potentials. The weldment of weathering steel was susceptible to both anodic dissolution SCC and hydrogen evolution HEC.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.115-121
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• 2000

As the development of industry water quality of river is going to bad because of waste water of an industrial complex and general home agricultural chemicals exhaust of $SO_3$ and CO gas acid rain and so on. Corrosion damage of boiler factory equipment and so forth occur quickly due to using of the polluted water resulting in increasing leak accident. Especially working life of hot water boiler using the polluted water becomes more short and energy loss increases. The cathodic protection method is the most economical and reliable one to prevent corrosion damage of steel structures. Mg-base alloys galvanic anode protection of cathodic protection method is suitable for than application of hot water boiler using water with high specific resistance such as tap water. This paper is studied on the cathodic protection characteristics of how water boiler. In tap water and 0.001mol/$\ell$ NaCl solution the characteristics of anodic polarization of Mg-base alloys galvanic anode and tube material is investigated the measurement of cathodic protection potential according to the time elaspsed is carried out.

• Journal of Surface Science and Engineering
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• v.48 no.2
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• pp.68-72
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• 2015

The corrosion behavior of metals and alloys for the safety of offshore structures in seawater was investigated for the application of sacrificial anodes. The experiments were focused on the polarization behaviors and the surface morphology of each metal after experiments. Pure Zn, pure Al (Al1050), Al alloys (Al5052, Al6061), Mg alloys (AZ31, AZ91D) and steel (SCM440) were assessed in 3.5% sodium chloride solution by means of potentiodynamic polarization to verify the galvanic corrosion potential ($E_{couple}$). Potentiostat plots were plotted to compare the surface and corrosion current density ($i_{couple}$) of metals as sacrificial anodes in seawater to protect steel alloy as a cathode. Al alloys showed the best performance as a sacrificial anode, on the other hand, Mg alloys showed overprotection behavior. The surface morphologies of sacrificial anodes were observed by FESEM and compared.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.559-568
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• 2019

Recently, the infrastructure of the marine environment has been increasing. Therefore, there has been increasing interest in increasing the durability of structures. The FRP Hybrid Bar with improved durability against corrosion was developed in recent years. On the other hand, studies that evaluate the corrosion resistance are insufficient. In this study, the corrosion resistance according to the type of rebar in concrete was assessed and analyzed. The experiment used steel bars and FRP Hybrid Bar. The corrosion test method was a galvanic current and half-cell potential method. The accelerated corrosion test was carried out by four levels (0%, 1.5%, 3%, and 6%) of chloride added to the concrete. The galvanic current measurements revealed no corrosion current in the FRP Hybrid Bar. The half-cell measurement also showed the corrosion resistance of the FRP Hybrid Bar. Therefore. FHB can be used as an alternative steel for structures where a marine environment and steel corrosion are predicted.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.475-476
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• 2010

Hydration products formed on the steel surface may impose the resistance to corrosion of steel when a concrete is exposed to a salt environment. In the present study, ordinary Portland cement (OPC), calcium aluminate cement (CAC) and calcium hydroxide are applied as coating materials on the steel surface to consider the hydrations of each binder at corrosion. Corrosion is measured in terms of the corrosion potential and galvanic current to detect the effects in mitigating the corrosion behavior.

• Corrosion Science and Technology
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• v.18 no.6
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• pp.312-317
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• 2019

The objective of this study was to investigate the corrosion behavior of aluminum (AA1100) in a mixed solution of 0 ~ 0.1 g/L Na₂S + 0.3 ~ 3 g/L NaCl + 0 ~ 10 mL/L H₂O₂. Potentiodynamic polarization tests were performed. Effects of solution compositions on corrosion potential, corrosion rate, and pitting potential of aluminum were statistically analyzed with a regression model. Results suggested that localized corrosion susceptibility of aluminum was increased in the solution with increasing concentration of NaCl because the pitting potential was lowered linearly with increasing NaCl concentration. On the contrary, H₂O₂ mitigated the galvanic corrosion of aluminum by increasing the corrosion potential. It also mitigated localized corrosion by increasing the pitting potential of aluminum. Na₂S did not exert a noticeable effect on the corrosion of aluminum. These effects of different chemical species at various concentrations were independent of each other. Synergy or offset effect was not observed.