• Corrosion Science and Technology
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• 제6권6호
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• pp.269-274
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• 2007

The corrosion of steel in concrete is significant in marine environment. Salt damage is one of the most detrimental causes to concrete bridges and port structures. Especially, the splash and tidal zones around water line are comparatively important in terms of safety and life-time point of view. During the last several decades, cathodic protection (cp) has been commonly accepted as an effective technique for corrosion control in concrete structures. Zn-mesh sacrificial anode has been recently developed and started to apply to the bridge column cp in marine condition. The detailed parameters regarding Zn-mesh cp technique, however, have not well understood so far. This study is to investigate how much Zn-mesh cp influences along the concrete column at elevated temperature. About 100 cm column specimens with eight of 10 cm segment rebars have been used to measure the variation of cp potential with the distance from Zn-mesh anode at both $10^{\circ}C$ and $40^{\circ}C$ in natural seawater. The cp potential change and current diminishment along the column specimens have been discussed for the optimum design of cp by Zn-mesh sacrificial anode.

• Journal of Advanced Marine Engineering and Technology
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• 제19권2호
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• pp.56-66
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• 1995

Recently, with theraped advancement in th oceanology such an ocean-going vessel and oceanic structures, there is a need to study the cavitation erosion-corrosion control of pump impeller, the partial element of ocean machinery, for more effective operation. Especially, the cathodic protection (impressed current method & Al-sacrificial anode method) was applied to sea water, and Cu-alloy material mixed Zn & Al was used as a control method of cavitation erosion-corrosion. In this study, used the piezoelectric vibrator with 20KHz, 24.mu.m to cavity generation apparatus, and investigated the weight loss, weight loss rate, electrode potential & current density etc. under this condition. According to test result, thos describes how to indentify an influence of the cathodic protection and Al & Zn addition in material development for the control of cavitation erosion-corrosion, and those will serve as fundamental data on the cavitation erosion-corrosion control of oceanic centrifugal pump.

• Journal of Advanced Marine Engineering and Technology
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• 제20권2호
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• pp.92-92
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• 1996

Recently, with the rapid development in the oceanic systems such as the oceanic structures and vessel, there occurs much interest in the impingement erosion-corrosion. In this paper, Cu-metal was tested by using of erosion apparatus with water-jet type and was investigated under the behaviour of impingement erosion-corrosion according to various environmental conditions, and the properties of Cu-metal were evaluated through the measurement by weight loss, weight loss rate, protective efficiency. The results were compared with those obtained using Cu-metal applied to cathodic protection and Cu-alloys added to Zn or Al-metal. As a basis of those results, the best protective efficiencies could be taken as using cathodic protection method and Cu-alloy with Al & Zn material addings, and will be suggested as the fundamental data of the anti-impingement erosion-corrosion on Cu-metal of impeller material for oceanic centrifugal pump.

• Journal of Advanced Marine Engineering and Technology
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• 제20권2호
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• pp.24-31
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• 1996

Recently, with the rapid development in the oceanic systems such as the oceanic structures and vessel, there occurs much interest in the impingement erosion-corrosion. In this paper, Cu-metal was tested by using of erosion apparatus with water-jet type and was investigated under the behaviour of impingement erosion-corrosion according to various environmental conditions, and the properties of Cu-metal were evaluated through the measurement by weight loss, weight loss rate, protective efficiency. The results were compared with those obtained using Cu-metal applied to cathodic protection and Cu-alloys added to Zn or Al-metal. As a basis of those results, the best protective efficiencies could be taken as using cathodic protection method and Cu-alloy with Al & Zn material addings, and will be suggested as the fundamental data of the anti-impingement erosion-corrosion on Cu-metal of impeller material for oceanic centrifugal pump.

• 한국표면공학회지
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• 제49권4호
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• pp.349-356
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• 2016

In this study, electrochemical damage behaviors with flow rate were investigated for anodized 5083 aluminum alloy in seawater. As the results of anodic polarization experiments and potentiostatic experiments at +1.0 V (vs. SSCE), the non-flow condition presented largely damaged surface resulting from a tendency of local pitting damage. Under various flow rate conditions, however, less surface damages under the application of anodic potential was obtained which is attributed to no accumulation of $H^+$ and $Cl^-$ ions on the surface. On the other hand, the results of the potentiostatic experiments at -1.0 V (vs. SSCE) with flow rate showed that anodized 5083 aluminum alloys could achieve the effective cathodic protection by low cathodic protection current density less than $2.61{\times}10^{-7}A/cm^2$ even under high flow rate of 1 m/s.

• 한국표면공학회지
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• 제52권2호
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• pp.103-110
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• 2019

As an anti-corrosion method in seawater, cathodic protection is widely recognized as the most effective and technically appropriate corrosion prevention methodology for marine structures against harsh corrosive environment. When applying the cathodic protection in seawater, the surface of the metal facilities the formation of compounds of $CaCO_3$ and $Mg(OH)_2$. These mixed compounds are generally called 'calcareous deposits'. This layer functions as a barrier against the corrosive environment and functions to further inhibit the corrosion process and then leading to a decrease in current demand for cathodic protection. However, calcareous deposit films are partially formed on the surface of the cathode and there are some difficulties to maintain both a corrosion resistance for a long period of time and a strong adhesion between deposits and base metal. In this study, the pulse electrodeposition process was applied to improve adhesion and corrosion resistance of the calcareous deposit films, and to solve the problem of hydrogen embrittlement at high current density. The uniform and compact calcareous deposit films were prepared by pulse electrodeposition process, and their properties were characterized using various surface analytical techniques together with electrochemical methods.

• 문화기술의 융합
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• 제5권4호
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• pp.367-371
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• 2019

본 연구에서는 해양성 기후조건에 있는 철도 레일의 부식으로 인한 선로장애를 최소화하고 레일의 부식을 저감시키기 위한 방식대책으로써 희생양극법을 제시하고 방식효과를 실험적으로 입증하였다. 또한 제안된 희생양극을 현장에 시험부설하여 26개월 이상 장기 레일부식모니터링 및 현장적용성을 검토하고 레일부식의 효과를 입증하였다. 셀로판테이프법을 이용한 부식상태 모니터링 결과, 현장시험부설 후 약 26개월이 경과된 현 시점에서의 희생양극의 외관상태는 양호하며, 레일복부와 희생양극의 용접부 이상 및 기타 특이사항은 발견되지 않았으나, 희생양극을 설치하지 않은 개소에서는 녹의 진전이 빠르게 진행되었다. 또한 희생양극의 적정 설치간격은 1.0~1.5m까지가 상대적으로 가장 안정적인 부식피막을 형성하는 것으로 조사되었다. 약 26개월의 모니터링 결과, 희생양극의 설치는 설치간격이 다소 넓더라도 해양성 기후조건에 있는 철도 레일의 전반적인 부식발생 수준을 안정화하는 데에 도움을 줄 수 있어 부식에 취약한 환경에 부설된 철도 레일에 적용이 가능할 것으로 분석되었다.

• 수산해양기술연구
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• 제25권2호
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• pp.87-104
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• 1989

Recently, with the tendency of more lightening, high-strength and high-speed in the marine industries such as marine structures, ships and chemical plants, the use of the aluminium Alloy is rapidly enlarge and there occurs much interest in the study of corrosion fatigue crack characteristics. In this paper, the initiation of surface crack and the propagation characteristics on the base metal and weld zone of 5086-H116 Aluminium Alloy Plate which is one of the Al-Mg serious alloy(A5000serious) used most when building the special vessels, were investigated by the plane bending corrosion fatigue under the environments of marine, air and applying cathodic protection. The effects of various specific resistances on the initiation, propagation behavior of corrosion fatigue crack and corrosion fatigue life in the base metal and heat affected zone were examined and its corrosion sensitivity was quantitatively obtained. The effects of corrosion on the crack depth in relation to the uniform surface crack length were also investigated. Also, the structural, mechanical and electro-chemical characteristics of the metal at the weld zone were inspected to verify the reasons of crack propagation behavior in the corrosion fatigue fracture. In addition, the effect of cathodic protection in the fracture surface of weld zone was examined fractographically by Scanning Electron Microscope(S.E.M.). The main results obtained are as follows; (1) The initial corrosion fatigue crack sensitibity under specific resistance of 25Ω.cm% show 2.22 in the base metal and 19.6 in the HEZ, and the sensitivity decreases as specific resistance increases (2) By removing reinforcement of weldment, the initiation and propagation of corrosion crack in the HAZ are delayed, and corrosion fatigue life increases. (3) As specific resistance decreases, the sensitivity difference of corrosion fatigue life in the base metal and HAZ is more susceptible than that of intial corrosion fatigue crack. (4) Experimental constant, m(Paris' rule) in the marine environment is in the range of about 3.69 to 4.26, and as specific resistance increases, thje magnitude of experimental constant, also increases and the effect by corrosion decreases. (5) Comparing surface crack length with crack depth, the crack depth toward the thickness of specimen in air is more deeply propagated than that in corrosion environment. (6) The propagation particulars of corrosion fatigue crack for HAZ under initial stress intensity factor range of $\Delta$k sub(li) =27.2kgf.mm super(-3/2) and stress ratio of R=0 shows the retardative phenomenon of crack propagation by the plastic deformation at crack tip. (7) Number of stress cycles to corrosion fatigue crack initiation of the base metal and the welding heat affected zone are delayed by the cathodic protection under the natural sea water. The cathodic protection effect for corrosion fatigue crack initiation is eminent when the protection potential is -1100 mV(SCE). (8) When the protection potential E=-1100 mV(SCE), the corrosion fatigue crack propagation of welding heat affected zone is more rapid than that of the case without protection, because of the microfissure caused by welding heat cycle.

• Corrosion Science and Technology
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• 제10권3호
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• pp.80-86
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• 2011

Welding was widely used in shipbuilding industries as a joining method. In present study, the effects of welding fume contaminated on steel surface on corrosion protection were examined by water ballast simulation test and condensation chamber test. Pull-off adhesion test, blistering test and cathodic disbondment test were carried out to evaluate the effects of residual welding fume. Consequently, it was clearly indicated that the residual welding fume didn't affect the corrosion protection of epoxy coated on steel when surface was treated by light sweep blasting to heavy sweep blasting which was applied in this study.

• 수산해양기술연구
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• 제28권2호
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• pp.216-227
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• 1992

The corrosion rate, behavior of corrosion fatigue and characteristic of cathodic protection for SB41 were investigated by corrosion and corrosion control tests in seawater at laboratory and coast. The main result obtained are as the following; 1) The corrosion rate of base metal (BM) is about 28-37 mg/dm super(2) day in seawater of coast. 2) The correlation between the stress intensity factor range $\Delta$K and crack propagation rate da/dN for weldment follows paris' rule in seawater : da/dN=C($\Delta$K) super(m) where m is the slope of the correlation, and is 2.02 for BM and 1.75 for heat affected zone (HAZ) respectively. 3) The corrosion sensitivity of HAZ is more sensitive than that of BM under the low region of $\Delta$K. 4) With increase of bared surace area of cathode, cathodic protection potential is increased sharply.