• Journal of Power System Engineering
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• v.10 no.2
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• pp.83-88
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• 2006

Corrosion characterization of Fe-XAl-0.3Y(X=5, 10, 14 wt%) alloys in $0.1{\sim}1N$ sulphuric acid at room temperature was studied using potentiodynamic techniques. The morphology and components of corrosion products on surface of Fe-aluminide alloys were investigated using SEM/EDX, XRD. The potentiodynamic polarization curve of alloys exhibited typical active, passive, transpassive behaviour. Corrosion potential($E_{corr}$) and corrosion current density($I_{corr}$) values of Fe-XAl-0.3Y alloys followed linear rate law. $E_{corr}$ of 10Al alloy and 14Al alloy was ten times lower than 5Al alloy. Icorr of 14Al alloy was five times lower than 5Al alloy. The passive film on the surface of Fe-5Al-0.3Y alloy was formed iron oxide. Fe-10Al-0.3Y and Fe-14Al-0.3Y alloys passive films were aluminium oxide. especially, Fe-14Al-0.3Y alloy showed good corrosion resistance in $0.1{\sim}1N$ sulphuric acid. This is attributed to the forming of protective $Al_2O_3$ oxide on the surface of Fe-14Al-0.3Y alloy.

• Journal of the Korean Chemical Society
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• v.56 no.2
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• pp.264-273
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• 2012

Five derivatives of phenylthiourea namely: 1-(4-methoxyphenyl)-3-phenylthiourea (1), 1-(4-methylphenyl)-3- phenylthiourea (2), 1-(4-bromophenyl)-3-phenylthiourea (3), 1-(4-chlorophenyl)-3-phenylthiourea (4) and 1-phenylthiourea (5) have been evaluated as new inhibitors for the corrosion of carbon steel in 2 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization measurements showed that these derivatives are mixed-type inhibitors. The inhibition efficiency was found to increase with inhibitor concentration and decreases with rise in temperature. The thermodynamic parameters of adsorption and activation were determined and discussed. Nyquist plots showed depressed semicircles with their centre below real axis. The adsorption process of studied derivatives on carbon steel surface obeys Temkin adsorption isotherm. The synergistic effect of these derivatives and some anions is discussed from the viewpoint of adsorption models. The electrochemical results are in good agreement with the calculated quantum chemical HOMO and LUMO energies of the tested molecules.

• Corrosion Science and Technology
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• v.5 no.1
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• pp.15-22
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• 2006

The introduction of two-grid inside a conventional process system produces a reactive coating deposition and increases metal ion ratio in the plasma, resulting in denser and smoother films. The corrosion behaviors of TiN coatings were investigated by electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 3.5% NaCl solution. Electrochemical tests were used to evaluate the effect of microstructure on the corrosion behavior of TiN coatings exposed to a corrosive environment. The crystal structure of the coatings was examined by X-ray diffractometry (XRD) and the microstructure of the coatings was investigated by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). In the potentiodynamic polarization test and EIS measurement, the corrosion current density of TiN deposited by two grid-attached magnetron sputtering was lower than TiN deposited by conventional magnetron type and also presented higher Rct values during 240 h immersion time. It is attributed to the formation of a dense microstructure, which promotes the compactness of coatings and yields lower porosity.

• Corrosion Science and Technology
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• v.13 no.1
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• pp.6-14
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• 2014

Copper metal is widely used in tubes installed in sprinkler water services because of its excellent corrosion resistance. Copper corrosion is considered to be insignificant in water system and the incident of copper pipeline failure is relatively low. However, pitting corrosion is a major problem with all copper tubes. In this study, leaked sprinkler copper tubes were collected from three different locations and examined on the causes of pitting corrosion of copper tubes in sprinkler water plumbing systems. Electrochemical tests such as potentiodynamic polarization, as well as surface and chemical analyses were performed. Results show that pitting corrosion of copper tubes were found as Type I pitting that the carbon film formed on the copper tubes have a harmful effects, causing the pinhole failure in the pipe and resulting in leakage of water. The contermeasures on Type I pitting corrosion of copper tubes were proposed.

• Korean Journal of Metals and Materials
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• v.46 no.12
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• pp.809-816
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• 2008

The influences of various parameters such as inclusions, surface roughness, exposed areas and chloride ion concentrations on the initiation of pitting of Fe-17Cr alloy were investigated, using micro-droplet cell technique. Micro-droplet cell allows one to align the micro-electrode to the desired spot of the working electrode and measure directly local currents with the potentiodynamic polarization. Micro electrochemical tests were carried out at the inclusions after EDX analysis of inclusion. EDX analysis identified inclusions as Cr-oxides. It was found that some active inclusions among Cr-oxide inclusions acted as initiation sites for pitting corrosion. In addition, the rougher surface and the denser chloride ion concentration offered easier pit initiation sites, causing the more susceptible to pitting corrosion.

• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.372-380
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• 2018

Anodization techniques are widely used in the area of surface treatment of aluminum alloys because of its simplicity, low-cost and good corrosion resistance. In this study, we investigated the relationship between the properties (porosity and thickness) of anodic aluminum oxide (AAO) and its corrosion behavior. Aluminum 5052 alloy was anodized in 0.3 M oxalic acid at $0^{\circ}C$. The anodizing of aluminum 5052 was performed at 20 V, 40 V and 60 V for various durations. The corrosion behavior was studied in 3.5 wt % NaCl using potentiodynamic polarization method. Results showed that the pore diameter and thickness increased as voltage and anodization time increased. The relatively thick oxide film revealed a lower corrosion current density and a higher corrosion potential value.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.139-147
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• 2019

Incorporation of CuO nanoparticles during the polymerization of aniline in the presence of ammonium peroxydisulphate as an oxidizing agent and sodium salt of dodecylbenzene sulphonic acid as dopant as well as surfactant yielded water soluble CuO-PANI composite. Comparison of recorded spectra like FTIR, XRD and SEM with reported one confirm the formation of the composite. Analysis by gravimetric method exposes that the synthesized composite is having resistivity against corrosion, with slight variation in efficiency on extending the time duration up to eight hours in strong acidic condition. OCP measurement, potentiodynamic polarization and EIS studies also confirms the suppression ability of composite against corrosion. Riskless working environment could be provided by the synthesized composite during industrial cleaning process.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.172-177
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• 2021

The microstructure and texture of three 316L foils of 25 ㎛ thickness, which were subjected to different manufacturing process, were systematically characterized using advance analytical techniques. Then, the electrochemical property of the 316L foils in simulated pressurized water reactor (PWR) solution was analyzed using potentiodynamic polarization. The results showed that final rolling strain and annealing temperature had evident effect on grain size, fraction of recrystallization, grain boundary type and texture distribution. It was suggested that large final rolling strain could transfer Brass texture to Copper texture; low annealing temperature could limit the formation of preferable orientations in the rolling process to reduce anisotropy. Potentiodynamic polarization test showed that all samples exhibited good corrosion performance in the simulated primary PWR solution.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.927-931
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• 2021

In this work, an attempt is made to improve the electrochemical corrosion resistance of Zircaloy-4 by helium ions implantation. For this purpose, the Zircaloy-4 was implanted with 300 keV helium ions of fluences 1 × 10¹³, 1 × 10¹⁵, and 1 × 10¹⁶ ions-cm^-2 by using Pelletron Accelerator. Electrochemical tests of pristine and ion-implanted samples were performed in NaCl solution and their potentiodynamic polarization curves were obtained. The results showed enhancement of the corrosion resistance of Zircaloy-4 after helium ions implantation. The corrosion rate and current density of the material were significantly reduced by the helium implantation. The decrease in corrosion parameters was attributed to helium ions diffusion inside Zircaloy-4 that reduced the electrons flow from the samples.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.43-44
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• 2022

In this study, the optimum amount of chloride ions is used to collaborate with hybrid corrosion inhibitor for carbon steel rebar treatment in simulated pore concrete (SCP) solution is discovered. The corrosion inhibition performance of hybrid inhibitors is carried on by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP). The highest corrosion inhibition resistance is found in case of LP-C2 after 240 h exposure. Surface studies including scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to figure out the surface morphology of the steel rebar treated with hybrid inhibitors in order to collaborate well with electrochemical studies. Anodic type inhibition action was confirmed by potentiodynamic polarization study.