• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.149-160
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• 2000

As systematic methodologies are required for the evaluation on the durability of reinforced concrete structure, it is necessary to study and examine every factor which deteriorates the durability of structures. This paper aims to define factors affecting rebar corrosion and to establish a basis for a prediction of serviceability, regarding a state of harmful corrosion as a state when crack begins on the surface of concrete. The study results are followings; The corrosive current has changed by types of mixture, and this property enables the evaluations of corrosion resistance by mixture and concrete cover. The specimen using AE superplasticizer has better corrosion-resistance properties than non-AE specimen, as well those having low W/C and high unit cement weight. The procedure for calculation of durable year in this study is able to use as an indicator to establish mixture factors such as unit cement weight, W/C, amount of admixture, etc.

• 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 Society of Industry Convergence
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• v.24 no.5
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• pp.517-523
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• 2021

In this study, in the selection of materials for the elements of a small plant, those with high resistance to corrosion are selected and the material properties of coatings for corrosion prevention are evaluated. In addition, corrosion characteristics and material analysis were performed on the welded part, and the hardness characteristics of the welded part, heat-affected part, and the base metal were evaluated. In the case of the post-weld-heat-treated(PWHT) specimen, the corrosion resistance of STS 316 was lower than that of the specimen without the PWHT due to the formation of intergranular carbide. As a result of evaluating the distribution of the hardness of the weld before and after the PWHT, the hardness of the specimen after the PWHT increased by about 20 Hv. As a result of the corrosion test on the welded specimen, the weight loss tended to increase as the time increased. In the case of the PWHT specimen, the corrosion resistance tended to be significantly lower than that of the specimen without PWHT due to the formation of intergranular carbide.

• Corrosion Science and Technology
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• v.18 no.1
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• pp.33-38
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• 2019

Alloy 600/182 with excellent mechanical/chemical properties have been utilized for nuclear power plants. Although both alloys are known to have superior corrosion resistance, stress corrosion cracking failure has been an issue in primary water environment of nuclear power plants. Therefore, primary water stress corrosion crack (PWSCC) growth rate tests were conducted to investigate crack growth properties of Alloy 600/182. To investigate PWSCC growth rate, test facilities including water chemistry loop, autoclave, and loading system were constructed. In PWSCC crack growth rate tests, half compact-tension specimens were manufactured. These specimens were then placed inside of the autoclave connected to the loop to provide primary water environment. Tested conditions were set at temperature of $360^{\circ}C$ and pressure of 20MPa. Real time crack growth rates of specimens inside the autoclave were measured by Direct Current potential drop (DCPD) method. To confirm inter-granular (IG) crack as a characteristic of PWSCC, fracture surfaces of tested specimens were observed by SEM. Finally, crack growth rate was derived in a specific stress intensity factor (K) range and similarity with overseas database was identified.

• Corrosion Science and Technology
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• v.20 no.3
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• pp.112-117
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• 2021

Inductively coupled plasma magnetron sputtering (ICPMS) has the advantage of being able to dramatically improve coating properties by increasing the plasma ionization rate and the ion bombardment effect during deposition. Thus, this paper presents the comparative results of CrN films deposited by direct current magnetron sputtering (dcMS) and ICPMS systems. The structure, microstructure, and mechanical and corrosive properties of the CrN coatings were investigated by X-ray diffractometry, scanning electron microscopy, nanoindentation, and corrosion-resistance measurements. The as-deposited CrN films by ICPMS grew preferentially on a 200 plane compared to dcMS on a 111 plane. As a result, the films deposited by ICPMS had a very compact microstructure with high hardness. The nanoindentation hardness reached 19.8 GPa, and 13.5 GPa by dcMS. The corrosion current density of CrN film prepared by ICPMS was about 9.8 × 10^-6 mA/cm², which was 1/470 of 4.6 × 10^-3 mA/cm², the corrosion current density of CrN film prepared by dcMS.

• Corrosion Science and Technology
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• v.21 no.6
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• pp.487-494
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• 2022

Anodizing is a typical electrochemical surface treatment method that can improve the corrosion and insulating properties of aluminum alloys. The anodization process can obtain a dense structure. It can be used to artificially grow the thickness of an anodization film. Aluminum 3003 alloy used in this study is the most commonly used alloy for batteries due to its high strength and excellent formability as well as its weldability and corrosion resistance. Aluminum 3003 alloy was anodized at 0 ℃ with 0.3 M oxalic acid at 20 V, 40 V, or 60 V for 1 hour, 6 hours, or 12 hours. As a result of analyzing the composition of each specimen with an Energy Dispersive Spectrometer (EDS), aluminum was converted into an oxide film. The thickness of the formed anodization film increased when the applied voltage and anodization time increased. High corrosion potential values and low corrosion current density values were observed for the thickest oxide layer. The anodization film formed by anodization acted as a protective layer. The electrical resistance increased as the applied voltage and anodization time increased.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.367-375
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• 2011

Succinic acid ester derivatives have been used as additives for the base oil of metal working fluids and pressure working oils. In this paper, a series of succinic acid alkyl half-esters were synthesized with over 97% yields by ring-opening reaction of succinic anhydride and fatty alcohol and were soluble in 100 N base oil within 1 wt% concentration. The structures and purities of ester derivatives were confirmed by $^1H-NMR$ and FT-IR spectrum and GC analysis. Anti-corrosion properties of the esters in sea water were evaluated through ASTM D665 method and weight loss method and compared to that of succinic alkyl esters without carboxylic acid group in the molecule. As the results, anti-corrosion properties of succinic acid alkyl half-esters with carboxylic acid group were better than those of succinic acid alkyl esters without carboxylic acid group. And, Anti-corrosion properties of the esters with a shorter alkyl chain of high concentration showed better performance than those with longer alkyl chain of low concentration. Inhibition efficiency % (IE%) of the esters was over 95% in the concentration of 80 ppm and corrosion rate (CR) was below 0.3 mm/year at the same concentration. Thus, the corrosion properties of succinic acid alkyl half-esters result from the carboxylic acid groups in molecules.

• Corrosion Science and Technology
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• v.8 no.2
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• pp.89-92
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• 2009

Pure Ti as well as Ti-6Al-4V alloy exhibit excellent properties for dental implant applications. However, for a better biocompatibility it seems important to avoid in the composition the presence of V due to the toxic effects of V ion release. Thus Al and V free and composed of non-toxic element such as Nb, Zr alloys as biomaterials have been developed. Especially, Zr contains to same family in periodic table as Ti. The addition of Zr to Ti alloy has an excellent mechanical properties, good corrosion resistance, and biocompatibility. In this study, the electrochemical characteristics of Ti-Zr alloys for biomaterials have been investigated using by electrochemical methods. Methods: Ti-Zr(10, 20, 30 and 40 wt%) alloys were prepared by arc melting and homogenized for 24 hr at $1000^{\circ}C$ in argon atmosphere. Phase constitutions and microstructure of the specimens were characterized by XRD, OM and SEM. The corrosion properties of the specimens were examined through potentiodynamic test (potential range of -1500 ~ 2000 mV), potentiostatic test (const. potential of 300 mV) in artificial saliva solution by potentiostat (EG&G Co, PARSTAT 2273. USA).

• Advances in concrete construction
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• v.2 no.3
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• pp.193-207
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• 2014

The study presented herein aims to investigate the durability related properties of rubberized concrete. Two types of waste scrap tire rubber were used as fine and coarse aggregate, respectively. The rubber was replaced with aggregate by three crumb rubber and tire chips levels of 5, 15, and 25% for the rubberized concrete productions. In order to improve the transport properties and corrosion resistance of rubberized concretes, SF was replaced with cement at 10% replacement level by weight of total binder content. The transport properties of the rubberized concretes were investigated through water absorption, gas permeability, and water permeability tests. The corrosion behavior of reinforcing bars embedded in plain and silica fume based rubberized concretes was investigated by linear polarization resistance (LPR) test. The results indicated that the utilization of SF in the rubberized concrete production enhanced the corrosion behavior and decreased corrosion current density values. Moreover, the reduction in the water and gas permeability coefficients was observed by the incorporation of SF in plain and especially rubberized concretes.