• Corrosion Science and Technology
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• 제4권2호
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• pp.56-59
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• 2005

In rebar concrete structure, the corrosion of rebar can arise the deterioration of concrete structure and may affect the safety of the whole system. Recently, several methods for corrosion protection have been used and are more important for concrete structure using the sand including chloride ion. Among several protections, electrical cathodic protection has been expected to be one of the most useful methods in corrosion protection for reinforcement of concrete structures. The anode for cathodic protection needs high current density, high corrosion resistance and low overvoltage. To fill up the special qualities, the insoluble anodes were developed and these anodes were coated with metal oxide of $TiO_2$, $ZrO_2$, $RuO_2$, and $IrO_2$. Lifetime of these anodes can be one of the important factors affecting the lifetime of concrete structure in cathodic protection. In this work, several anodes were made by sol-gel method and thermal decomposition method and the lifetime of these anodes was evaluated by NACE international standard test method, TM 0294-94. Also, we did analyze the properties of coated metal oxides.

• Journal of Advanced Marine Engineering and Technology
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• 제17권1호
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• pp.55-65
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• 1993

Galvanic protection method is one the cathodic protection methods and is mostly used for corrosion prevention of heat exchangers and ship's hull. In this paper, it was investigated that how cathodic potential distribution was varied with according to the bare and painted steel plates in case of galvanic anode protection. The results obtained above were as follows. 1. Cathodic potential distribution of a painted steel plate was smoothed than that of the bare steel plate all over the cathodic surface area. 2. It was shown that polarization potential of the bare steel plate was somewhat shifted to negative potential, on the contrary that of the painted steel plate was somewhat shifted from negative potential to positive potential as time gone by beginning of galvanic anode method. 3. The applied current density in order to maintain constant protection potential(-770mv SCE) in the painted steel plate was less than that of the bare steel plate because of the high resistance polarization of the painted steel plate. 4. It was suggested that required number and life-time of anode for galvanic anode protection could be decided easily with corrosion prevention coefficient obtained by experimental data.

• Journal of Welding and Joining
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• 제11권3호
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• pp.61-74
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• 1993

The cause of corrosion failure found in structures or various components operating in severe corrosive environment has been attributed to stress corrosion cracking(SCC) which is resulting from the combined effects of corrosive environments and static tensile stress. Cathodic protection is an electrochemical method of corrosion control that is widely used in marine environment and primarily on carbon steel. A number of criteria are used to determine whether or not a structure is cathodically protected. In practice, -0.8V versus Ag/AgCl is the most commonly used for marine structures. This paper showed the combined effects of cathodic potential and slow, monotonic straining on the tensile ductility and fracture morphology of parents and friction welded joints for SM45C, SCM440 and SM20C steels in syntheic sea water(S.S.W.,pH:8.2). For the parent materials in cathodic potentials, the higher tensile strength is, the more susceptible SCC is. And the welded HAZ is more susceptible than the parent materials.

• 대한기계학회논문집
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• 제14권2호
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• pp.492-501
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• 1990

It was known that the fracture incidences of offshore structure were mostly originated from the surface defects. Especially, in the case of the welded structures, since the welded region has some defects and incomplete beads which are apt to behave like the surface cracks, it has been necessary to evaluate the environmental effects on crack growth at HAZ for the design crack growth behaviour at multi-pall HAZ for SWS41 steel under free corrosion and cathodic protection(-0.9V vs Ag/Agcl) conditions. The results are summarized as follows ; (1) Crack growth rate of the as weld in air was faster than that of the parent and PWHT specimens over all .DELTA.K rang. (2) In free corrosion test, surface crack growth rate of the as welded was decreased in comparison with that of the parents. (3) In fatigue test under cathodic protection, cathodic electric potential(-0.9V vs Ag/Agcl) for the SWS41 steel parent was effective, while for the as welded ineffective. (4) There was a tendency that the exponent(m) of the Paris' equation was decreased in order of microhardness magnititude in air and under cathodic protection conditions and vise versa in free corrosion. (5) Fracture surface has dimples and ductile striations in air test, but transgranular cracks and brittle striations under cathodic protection test.

• Corrosion Science and Technology
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• 제16권6호
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• pp.294-297
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• 2017

For the longer service life of steel pile, cathodic protection is selected sometimes at corrosive environment. The cathodic protection design improvement was investigated in this study. The current demand for cathodic protection was calculated from the potentiostatic current monitoring of the steel specimen in the deaerated soil samples. In this study, the current distribution was studied using the Boundary Element Method (BEM) and the Finite Element Method (FEM) numerical analysis methods. The optimum layout of the anode was developed and confirmed by numerical analysis. Under the conventional design of the anode, the length of the anode hole is same as the pile length. We found that, at the bottom end of the pile, the current density is too high. When the anode hole length was 80% of the pile length, the current consumption at the end was reduced. The construction cost of anode hole drilling was decreased about 20%, as compared to the conventional design. Furthermore, the life of the anode materials could be extended by reducing the current consumption at the end section. Using this approach, the construction cost was reduced significantly without any under-protection area on the steel piles.

• 한국표면공학회지
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• 제43권2호
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• pp.51-56
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• 2010

The zinc electroplating with respect to the chloride concentration was investigated by X-ray diffraction(XRD), scanning electron microscope (SEM), and cathodic polarization measurement. The cathodic overpotential during electroplating was first decreased and then increased with increase of chloride concentration in electrolyte. The decreased cathodic overpotential leads to preferred orientation of (002) plane, high current efficiency and satisfactory zinc deposits. The increased cathodic overpotential causes random orientation, low current efficiency and edge burning. The cathodic overpotential was affected by chloride concentration in electrolyte, not by the kind of chloride, such as NaCl and KCl. An optimized chloride concentration was 3 M for zinc electroplating. Also, it is considered that NaCl can be a alternation for KCl as a main salt of zinc electroplating bath.

• 약학회지
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• 제29권3호
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• pp.144-151
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• 1985

Cathodic stripping voltammetric determination of traces of selenium in plant samples was studied. Stripping peak of selenium (IV) from Cu-Se intermettalic deposit in acidic media containing copper (II) ion is specific, highly sensitive and well defined, is successfully used for the quantitative determination of selenuin down to the level of 1ng/ml. Sample is burnt in a calorimeter bomb under the oxygen pressure of 40atm. and the selenium is absorbed in 0.1M NaOH. After the solution is filtrated, concentrated and acidified with HCl, then passed through a column of cation exchange resin in the $H^{+}$ form(Dowex 50X-8). The column eluate is analyzed for selenium by differential pulse cathodic stripping voltammetric method. Analytical results of selenium for NBS SMR is well agreement with the certified values. Results are given for a series of plant materials.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.87-92
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• 2001

Reinforced concrete have defect in durability due to carbonation, freezing and thawing, and penetration of chloride ions with time in spite of superb structure. Especially steel corrosion in concrete due to penetration of chloride ions have result in a marked decline in service life. The principal purpose in this study is to see effect of sacrificial anode cathodic system, one of the electrochemical methods in order to the control of steel corrosion in concrete. There are chloride content in concrete in cracked and no cracked specimen with cathodic protection. To recognize the effect of sacrificial anode cathodic protection, Instant-off potential are measured. We have the excellent effect for control steel corrosion adaption sacrificial anode cathodic system.

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.584-590
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• 1997

Harbour marine steel structures, which are served in severe marine environment, should be protected in appropriate method to reduce corrosion problems. Cathodic protection, one of the protection methods in terms of practical and economical point of view is being widely used to marine steel structures mentioned above. Recently it has been reported that the life of Al alloy anode with sacrificial anode for protection of harbour marine steel structures was shortened significantly than the original design life. In this study, the optimum cathodic protection design of harbour marine steel structures was investigated with parameter of sea water pollution degree.

• Journal of Advanced Marine Engineering and Technology
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• 제37권3호
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• pp.260-265
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• 2013

Impressed current cathodic protection (ICCP) system is one of the most promising corrosion protection methods. The Effect of ICCP system can be changed at diverse conditions. Particularly, temperature and relative humidity plays a crucial role in CP (Cathodic Protection) effect. Thus, in this study, the influence of temperature and relative humidity on concrete specimens was investigated. Specimens were concrete slab type with a base of $400mm{\times}400mm$ and height of 70mm. To enhance the effect of CP system, seawater was used as an electrolyte. Used anode for ICCP system was mixed metal oxide (MMO) titanium. Test factors were natural potential, CP potential, CP current, and 4-hour depolarization potential. From this study, it could be confirm that CP potential and current were highly influenced by temperature and relative humidity.