• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.125-131
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• 2002

This paper was studied on the effect of temperature on corrosion of absorption refrigeration systems using $LiBr-H_2O$ working fluids. In the fresh water and 62 % lithium bromide solution at $70^{\circ}C$, polarization test of SS 400, Cu(C1220T-OL) and Al-Ni bronze was carried out. And polarization behavior, polarization resistance characteristics, corrosion rate(mmpy) and corrosion sensitivity of materials forming absorption refrigeration systems was considered. The main results are as following: (1) As the experimental temperature increase, the change of corrosion rate of Al-Ni bronze become duller than SS 400 and Cu in 62% lithium bromide solution. (2) According as corrosion environment is changed from fresh water to 62% lithium bromide solution, potential change of Cu and Al-Ni bronze become less noble than SS 400. (3) The corrosion sensitivity of Al-Ni bronze was duller than that of Cu and SS 400 in 62% LiBr solution.

• 수산해양기술연구
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• 제36권1호
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• pp.66-72
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• 2000

본 연구에서는 오스테나이트계 스테인리스 강재(STS 304)에 대해 NaCl 환경 중에서 틈부식 특성을 연구하기 위해, 정전압 분극장치에 의해 분극특성시험을 실시하여 NaCl 용액의 농도에 따른 STS 304 강재의 틈부식에 의한 분극 거동에 대해 연구한 결과는 다음과 같은 결론을 얻었다. 1) 틈부위는 심하게 부식되고 틈의 인접한 외부 표면은 부동태화된다. 2) 오스테나이트계 스테인리스강재인 STS 304 강재는 분극거동에 있어서 부식 전위는 3.5% NaCl까지 농도가 증가할수록 귀전위화되다가 농도가 3.5%이상으로 증가할수록 오히려 비전위화된다. 3) 부식 전위하에 전류밀도는 NaCl 농도가 3.5%까지 증가할수록 더 많이 배류되다가 3.5% 이상으로 증가할수록 오히려 더 적게 배류된다.(이 논문의 결론(요약) 부분임)

• Corrosion Science and Technology
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• 제7권1호
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• pp.35-39
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• 2008

We have been studying application of electrochemical noise (Fluctuation) analysis for localized corrosion. Foils of Zinc, Aluminum and Magnesium were used as specimens for electrochemical cell simulating localized corrosion. These specimens were dipped in sodium chloride solutions adjusted to each exponent of Hydrogen ion concentration (pH) condition of 5.5, 10, 12 respectively. Time variations of potential and current were measured in those solutions, and simultaneously the surfaces of specimens were observed using microscope with television monitor. Two types of electrochemical cells were arranged for experiments simulated localized corrosion. The fluctuations on trendy component of short-circuited potential and short-circuited current were appeared in synchronization. It was seemed that these fluctuations result from hydrogen evolution on the aluminum active site in the crevice from the microscopic observation. In the case of zinc and magnesium, fluctuations appeared on the trendy component of the corrosion potential. Two types fluctuation were detected. First one is the fluctuation varied periodically. The second one is the random fluctuation. It was seemed that these fluctuations result from generation of corrosion products and hydrogen evolution on the active site in the crevice of zinc and magnesium from the microscopic observation.

• 전기화학회지
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• 제10권3호
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• pp.175-178
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• 2007

Pure iron, Fe-0.4, and 1.2 wt.%Cu alloys were examined by conducting the electrochemical techniques in the weakly alkaline solution, pH9, controlled by $Ca(OH)_2$, solution added with 0.02M NaCl. The $R_P$ measured from ac impedance, selected 10 kHz and 10mHz, in weakly alkaline solutions containing chloride ions indicated that the addition of copper up to 1.2wt.% into the pure iron significantly improved the pitting resistance of iron. In contrast to alloy, the pure iron showed the rapid pitting occurrences in drying period. During the drying period, the corrosion potential of pure iron was shifted to less noble value, pitting initiation.

• Corrosion Science and Technology
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• 제22권6호
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• pp.429-434
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• 2023

This study investigated the localized corrosion behavior of a UNS G41400 steel surface treated with manganese phosphate. The phosphate coating, primarily composed of oxygen (O), phosphorus (P), and manganese (Mn) elements, had an approximate thickness of 6 ㎛. The particles comprising the coating varied in size by several micrometers; smaller particles were mainly composed of O, P, Mn, and iron (Fe) elements, indicating incomplete formation of the manganese phosphate film. Potentiodynamic polarization curves revealed a decrease in anodic current after surface treatment and a shift in corrosion potential toward the noble direction after treatment. After immersion in a 3.5 wt% NaCl solution for 96 hours, localized corrosion was observed, with some regions retaining residual phosphate film. Even though localized corrosion occurred on the treated surface, it was less severe than that on the untreated UNS G41400 steel surface. These findings suggest that manganese phosphate coating improved resistance to localized corrosion.

• Journal of Advanced Marine Engineering and Technology
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• 제15권1호
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• pp.51-58
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• 1991

Corrosion fatigue test was performed by the use of plane bending fatigue tester in marine environment having various specific resistance from 25(natural sea water) to 5000.ohm.cm. It is in order to investigate the effects of marine environmental factor on the corrosion fatigue fracture of SS41 steel. The main results obtained are as follows; 1. The aspect ratio(b/a) of corner crack growing in natural sea water is lower than that in air. 2. The surface crack growth rate(da/dN) in marine environment is faster than that in air and da/dN delaies with the specific resistance increased. 3. The experimental constant m of paris rule [da/dN=C(${\delta}$K)$^m$] decrease with the specific resistance decreased and the effect of corrosion in proportion to the specific resistance is more sensitive than that of stress intensity factor range(${\delta}$K) under region II. 4. The accelerative factor(${\alpha}$) in marine environment is about 1.1-2.7 and .alpha. is increase under the low region of stress intensity factor range(${\delta}$K). 5. The electrode potential($E_0$) gets less noble potential with the specific resistance decreased.

• 한국가스학회지
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• 제9권1호
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• pp.21-25
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• 2005

가스보일러용 오스테나이트계 스테인리스강재(STS 304)의 부식거동에 관해 연구하기 위하여, 응축수중에서 전기화학적 부식시험을 수행하여. STS 304의 전기화학적 부식거동을 고찰하였다. 다음과 같은 결론을 얻었다. 1)중성환경인 pH=6.5에서 pH가 낮아질수록 STS 304의 분극저항은 감소하고, 부식전위는 비전위화된다. 2)중성 및 산성환경 중에서 STS 304의 부식반응기구는 음극지배로 판단된다. 3) pH가 중성 환경인 pH=6.5에서 강산성 환경인 pH=0.5로 낮아질수록 STS 304의 부동태 전위영역이 감소하고 부동태유지 전류밀도는 증가하고 있다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.373-378
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• 2000

The crevice corrosion of local corrosion occur when the gap exist on metal surface. This crevice corrosion happen to region such as flange of pipe, contact part of casing, under gasket and packing, between valve disk and seat of pump etc. Especially The crevice corrosion of mild steel(SS 400) get serious. This paper was studied on the crevice corrosion of SS 400 in fluid environment. In $0\%,\;2\%,\;3.5\%,\;5\% NaCl$ solution, the aspect of the crevice corrosion and polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 with crevice and non-crevice was measured according to the NaCl concentration. The main results obtained are as follows : 1) Under crevice corrosion, the corrosion potential become less noble as the concentration of NaCl solution increased. 2) The current density under open circuit potential was high drained as concentration of NaCl solution increased by $3.5\%$ but the concentration increased over $3.5\%$, the current density was low drained. 3) The weight loss rate of SS 400 was increased as concentration of NaCl solution Increased by $3.5\%$, but the concentration increased over $3.5\%$, that of SS 400 was decreased. 4) Effect of oxygen for crevice corrosion in the concentration of $3.5\%$ NaCl solution become sensitive than that $0\%$ NaCl solution.

• 수산해양기술연구
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• 제37권2호
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• pp.147-152
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• 2001

본 연구에서는 수도수 중에서 Mg합금유전양극에 의한 연강재 온수보일러의 음극방식특성을 연구한 결과 다음과 같은 결론을 얻었다. 1) 온수보일러 관체의 개로전위에서나 전위가 높은 구간에서 모재의 부식전류밀도가 용접부위의 부식전류밀도보다 더 적게 배류된다. 2) 주조된 표면 그대로의 Mg합금 유전양극의 전류밀도는 주조된 표면을 연마한 상태의 Mg합금 유전양극의 전류밀도보다 더 많이 배류된다. 3) Mg합금 유전양극으로부터 거리가 멀어질수록 연강재 온수보일러의 음극방식전위는 높게 나타나고, 음극방식시간이 경과하면서 방식전위는 높게 나타나다가 6-10일 이후부터 방식전위는 안정되고 있다.

• 수산해양기술연구
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• 제30권4호
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• pp.312-319
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• 1994

Recently, with the rapid development in the industries such as an iron mill and chemical plants, there is enlarged by the use of the piping. Sepecially, the piping connected with a fluid, if it is increase the speed of running fluid, ought to generate cavitation phenomenon with unbalanced pressure. So, the cavitation phenomenon cause serious damage of the piping, because it generate erosion and corrosion in the piping. In this study, the steel pipe piping water (SPPW) and SPPW on weldment were tested by using of cavitation-erosion test apparatus with nozzle and were investigated under the marine environment of liquid. (specific resistance : 25 $Omega$. cm) The main results obtained are as follows : 1) The total weight loss and weight loss rate of affected zone of weldment by corrosion-erosion in the sea water are more increased than that of base metal. 2) The electrode potential by corrosion-erosion in the sea water becomes less noble than that of base metal, and current density is more increased. 3) As time goes by, the total weight loss and weight loss rate by cavitation erosion-corrosion in air-liquid 2 phase flow become more increased then those in only liquid solution. but these values turn to be decreased.