• Journal of Welding and Joining
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• 제32권4호
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• pp.55-62
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• 2014

The use of light-weight Al alloys in the automotive industry is increasing to meet requirements for fuel efficiency and emission reduction. Joining Al alloy to the conventional steel sheet is also very important issue with the increased use of Al alloy, and several joining processes have been introduced to enhance joining strength between dissimilar metals. This paper deals with a galvanic corrosion in the dissimilar metal joining. Salt spray tests up to 2000 hours were conducted on a self-piercing rivet, spot welded, adhesive bonded and weld-bonded joints, and cross-sections and tensile shear strength according the salt spray duration were analyzed at every 500-hour. Self-piercing rivet joint had relative low initial strength but the joint strength did not change regardless of the salt spray duration. The strength of other joints (spot welded, adhesive bonded and weld-bonded joints) decreased with the increase of salt spray duration and the corrosion behaviour of each joint was discussed.

• 한국해양공학회지
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• 제17권3호
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• pp.52-56
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• 2003

This study investigates the photoelectrochemical behavior of STS304 steel with TiO2 thin films coating, applied by sol-gel mehod, for the purpose of cathodic photoprotection of the steel corrosion. One time TiO2-coated STS304 steel, adapted with two kinds of TiO2 sol solution, has the most dominant photopotential abilities, which was -200mV vs. SCE and -500mV vs. SCE under illumination with 40 W fluorescent lamp, respectively. That had yielded more negative values than the corrosion potential of the bare metal(-130mv vs.SCE). The bleaching of TCE was confirmed on TiO2-coated STS304 steel under UV-illumination with 20W Black-light. This Study concluded that Ti02-coated STS304 exhibited both a cathodic photoprotection effect against corrosion and a photocatalytic self-cleaning effect.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.53-55
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• 2013

Nitrite-Type hydrocalumite (calumite) is a material that can provied a self-corrosion inhibition function to the reinforce concrete. In this study, bisphnol A·F type epoxy-midified mortars without hardner contaning calumite is prepared with various polimer-binder ratios, calumite contents and tow types of curing condition, and tested for flexural and compressive strength tensile strength and corrosion-inhibition. As a result, in the case of wet/dry curing condition, strengths of bisphnol A·F type epoxy-modified mortars without hardener contaning calumite is inclined to decrease with increasing of polymer-binder ratio and calumite content. However, dry cured specimens are slightly improved by using bisphnol A·F type epoxy resin. Finally, regardless of polymer-binder ratios and calumite contents, corrosion-inhibition of bisphnol A·F type epoxy-modified mortars without hardener containing calumite is superior than that of unmodified mortar.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.609-623
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• 2021

Buckling restrained bracing (BRB) was firstly introduced in Japan construction industry in year 1989. With time, BRB performance has been advanced to self-centering BRB (SC-BRB) which has exceptional energy dissipation, addressing the improvement in the structure performance in post-seismic affect. Although the BRB performance specifications are defined in design codes of several countries, specific design provisions are not generally provided since BRBs are usually considered a manufactured device. Furthermore, most of review papers focused on BRB rather than SC-BRB. Thus, this paper explores the background of both BRB and SC-BRB. The importance of self-centering components in BRB and literature related to it have been studied. This review study also highlights the significance of corrosion-resistance materials in the configuring BRB and SC-BRB since most of such members are made of carbon steel that is susceptible to corrosion.

• 한국재료학회지
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• 제29권12호
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• pp.812-817
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• 2019

A zinc-air battery is one of most promising advanced batteries due to its high specific energy density, low cost, and environmental friendliness. However, zinc anodes in zinc-air batteries lead to several issues including self-discharge, corrosion reaction, and hydrogen evolution reaction (HER). In this paper, viscosity of electrolyte has been controlled to suppress the corrosion reaction, HER, and self-discharge behavior. Various viscosity average molecular weights of poly(acrylic acid) (PAA) are adopted to prepare the electrolyte. The evaporation of electrolytes is proportional to the increase in molecular weight. In addition, enhanced self-discharge behavior is obtained when the gelling agent with high molecular weight is used. In addition, the zinc-air cell assembled with lower viscosity average molecular weight of PAA (M_v ~ 450,000) delivers 510.85 mAh/g and 489.30 mAh/g of discharge capacity without storage and with 6 hr storage, respectively. Also, highest capacity retention (95.78 %) is obtained among studied materials.

• 접착 및 계면
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• 제22권2호
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• pp.47-56
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• 2021

자기치유 소재를 이용하여 강판을 코팅하는 경우, 코팅 소재에 상처가 날 경우 스스로 상처를 치유하여 강판이 부식되는 것을 방지할 수 있다. 하지만 자기치유 과정에는 시간이 소요되며, 따라서 자기치유가 되기 전에 강판의 상처가 부식 될 수 있다. 본 연구에서는 가역적인 hindered urea bond(HUB)를 통하여 가교 결합을 형성하면서 동시에 부식 방지제로써 작용하는 DTBEDA를 이용하여 듀얼자기치유 메커니즘을 가지는 코팅 소재를 제조하였다. 또한 제조된 소재를 강판에 코팅하여 의료용 메스와 나노/마이크로 압입시험기를 통하여 스크래치에 대한 자기치유 성능을 확인하였으며, DTBEDA의 내부식성 효과를 전기화학 임피던스 분광법(EIS)을 통하여 분석하였다.

• Journal of Welding and Joining
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• 제11권2호
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• pp.42-52
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• 1993

The corrosion fatigue fracture behaviour of dual phase steel was investigated in 3% NaCl solution at 302MPa and 137MPa. Fatigue test was conducted by cantilever type of self-made rotary bending fatigue testing machine. The fatigue strength increased with increasing the hardness of 2nd phase. Corrosion pit originated at the boundary of the 2nd phase. The size and number of corrosion pits were influenced by the 2nd phase hardness, and pits remained constant in size just after they were transited into cracks. The life of crack initiation was effected by stress level. The shape of relation of .DELTA. K and da/dN has smaller scattering in it in 3% NaCl solution than that in air. The higher the 2nd phase hardness is, the greater the corrosion fatigue life becomes. Corrosion fatigue fracture behaviour was primarily effected by mechanical factor in case of high stress(302MPa), but by electro-chemical reaction in a lower stress(137MPa). As stress level got lower and hardness of the 2nd phase got higher, the roughness of fracture surface increased.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.271-272
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• 2006

Zinc confers high corrosion resistance by acting as a sacrificial anode, and a zinc coating improves the appearance of steel. Chromate conversion coating (CCC) films are still one of the most efficient surface treatments for steel. Although such films can self-repair via the dissolution of Cr(VI), dissolved Cr(VI) have adverse effects on humans, and the environment. Therefore, we examined the corrosion protection property and morphology of colloidal silica conversion films as an alternative to CCC films. The corrosion behavior was investigated in 3% NaCl solution using electrochemical techniques, including electrochemical impedance spectroscopy, open circuit potential, and the salt spray test(SST). Corrosion was implied by the appearance of red rust on the specimen surface. In corrosion resistance at 3% NaCl solution, red rust appeared at 15-20, 55-70, and 83-98 days on Zn-electroplated steel, colloidal silica conversion-coated specimens, and CCC-coated specimens, respectively. In the salt spray test, the colloidal silica film provided better corrosion protection than CCC films, i.e., red rust appeared at 96 hours on the Zn-electroplated steel sheet, at 432 hours with the CCC films, and at 888 hours with silica conversion coating.

• 한국표면공학회지
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• 제52권2호
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• pp.96-102
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• 2019

Magnesium and its alloys are prone to be corroded, thus surface treatments improving corrosion resistance are always required for practical applications. As a surface treatment of magnesium alloys, plasma electrolytic oxidation (PEO), creating porous stable oxide layer by a high voltage discharge in electrolyte, enhances the corrosion resistance. However, due to superhydrophilicity of the porous oxide layer, which easily allow the penetration of corrosive media toward magnesium alloys substrate, post-treatments inhibiting the transfer of corrosive media in porous oxide layer are required. In this work, we employed a hydrophobizing method to enhance the corrosion resistance of PEO treated Mg alloy. Three types of hydrophobizing techniques were used for PEO layer. Thin Teflon coating with solvent evaporation, self-assembled monolayer (SAM) coating of octadecyltrichlorosilane (OTS) based on solution method and SAM coating of perfluorodecyltrichlorosilane (FDTS) based on vacuum method significantly enhances corrosion resistance of PEO treated Mg alloy with reducing the contact of water on the surface. In particular, the vacuum based FDTS coating on PEO layer shows the most effective hydrophobicity with the highest corrosion resistance.

• Journal of Electrochemical Science and Technology
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• 제3권3호
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• pp.123-134
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• 2012

The electrochemical performance of positive pole grids of lead-acid batteries made of Pb-0.08%Ca-1.1%Sn alloys without and with 0.1 wt% of each of Cu, As or Sb and with 0.1 wt% of Cu, As and Sb combined was investigated by electrochemical methods in 4.0 M $H_2SO_4$. The corrodibility of alloys under open-circuit conditions and constant current charging of the positive pole, the positive pole gassing and the self-discharge of the charged positive pole were studied. All impurities (Cu, As, Sb) were found to decrease the corrosion resistance, $R_{corr}$ after 1/2 hour corrosion, but after 24 hours an improvement in $R_{corr}$ was recorded for Sb containing alloy and the alloy with the three impurities combined. While an individual impurity was found to enhance oxygen evolution reaction, the impurities combined significantly inhibition this reaction and the related water loss problem was improved. Impedance results were found helpful in identification of the species involved in the charging/discharging and the self-discharge of the positive pole. Impurities individually or combined were found to increase the self-discharge during polarization (33-68%), where Sb containing alloy was the worst and impurities combined alloy was the least. The corrosion of the positive pole grid in the constant current charging was found to increase in the presence of impurities by 5-10%. Under open-circuit, the self-discharge of the charged positive grids was found to increase significantly (92-212%) in the presence of impurities, with Sb-containing alloy was the worst. The important result of the study is that the harmful effect of the studied impurities combined was not additive but sometimes lesser than any individual impurity.