• Corrosion Science and Technology
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• v.4 no.4
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• pp.155-163
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• 2005

Heavy duty coating are required to have minimum durable period of 15 years under average usage environment because these paints are coated with purpose of anti-corrosion, antifouling, plastering etc. Onto steel structures constructed upon land and sea and other ferrous structures of electric power generation plants, electricity transmission towers, large structures of various plants, etc. Therefore we tried to estimate heavy duty coating longevity through reliability evaluation method and used combined cyclic anti-conrrosion test method composed of drying, moisturizing and salt spray as for accelerated life test to estimate longevity. Accelerated life test hours to heavy duty coating of first grade (with longevity not less than 15 years) specification may be obtained from troubleless test hours $t_n=\frac{B_p}{n^{1/\beta}}\left[\frac{1n(1-CL)}{1n(1-p)} \right]^{1/\beta}=19.671$ (yr) where shape parameter $\beta=1.1$, confidence level CL=80 %, warranty life $B_{10}=15$ yr and sampling size n=10 (2 sets). Because acceleration factor {AF} found by accelerated test is 41.7, accelerated life test hours required may be represented about 4,132 hr so that if this amount of hours is converted to number of cycles(6 hr/cycle) of complex cycle corrosion resistance test then the amount is tantamount about 690 cycles. That means if there does not occur trouble failure (with defect factor sum not more than 20) during when there is performed 690 cycles of combined cyclic anti-corrosion test to heavy duty coating specimen then it signifies that there can be warranted longevity $B_{10}$ of 15 yr under condition of confidence level CL=80 %.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.31-38
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• 2000

Anti-corrosion behaviour of rebar embedded in cement mortar containing chloride ions was investigated by electrochemical chloride extraction(ECE). $43\%$ of the initial chloride ions of the cement mortar was fixed to Friedel salts and the soluble chloride ions were successfully extracted by ECE method. Concentration profiles of the chloride ions were estimated by Fick's 2nd law with time and depth, and it was close to the real value. The corrosion potential increased to anodic direction after ECE test, and the corrosion of rebar was reduced as a result of AC impedance spectroscopy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.95-103
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• 2013

Half Cell Potential (HPC) technique has been widely adopted for its quantitative evaluation of corrosion possibility. In this study, RC specimens with three different cover depths (10mm, 30mm, and 60mm) and w/c ratios (0.35, 0.55, and 0.70) are prepared and accelerated salt spray test (SST) is performed for 45 days. Steel corrosion occurs in the specimens with 0.55 of w/c and 10mm of cover depth. In the case of 0.70 of w/c and 30mm of cover depth, steel corrosion is also monitored. Considering the effect of cover depth and w/c ratio, HCP evaluation equation is proposed and the condition which can control steel corrosion is obtained. Furthermore, anti-corrosive conditions containing w/c ratio and cover depth are analyzed through Life 365 program and the conditions are compared with the results from this study.

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.379-388
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• 1998

The iron-zinc interfacial reaction and corrosin properties in galvanizing bath containning Ni have been intestigated. The substrate steel plates were galvanized in Zn or Zn-0.018Al baths with various Ni contents. The corrosion resistance of galvanized specimens was also evaluated by $60^{\circ}$bending test for galvannealing speaaimens. The corrosion resistance was improved with Ni addition in pure Zn bath, while deteriorated with Ni addition in Zn-0.18Al bath. The anti-powdering property, on thhe otherhand, was improved with Ni addition in Zn-0.18Al bath, while deteriorated with Ni addition in pure Zn. It was found that the anti-powdering property was improved with increasing $\xi$ phase ratio in reaction layer.

• Corrosion Science and Technology
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• v.15 no.1
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• pp.28-37
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• 2016

Due to the increased construction of offshore concrete structures and the use of de-icing salts for the purpose of snow removal, the needs for the development of anti-corrosive concrete are increasing. To solve these problems, an evaluation of the mechanical and durability properties for concrete were conducted by mixing modified-sulfur as 0 %, 5 %, 10 %, 15 % cement weight ratio. Both strengths and the properties affecting durability such as water absorption coefficient, chloride ion permeability, accelerated carbonation resistance, rapid freezing and thawing, and chemical resistance were evaluated. All evaluations performed were according to the test specifications associated KS. The results indicate that mixing of modified-sulfur lowed chloride ion permeability and improved chemical resistance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.203-207
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• 1998

After etching Al-Cu alloy films using $SiCl_4/Cl_2/He/CHF_3$ plasma, a corrosion phenomenon on the metal surface has been studied with XPS (X-ray photoelectron spectroscopy) and SEM (Scanning electron microscopy). In Al-Cu alloy system, the corrosion occurs rapidly on the etched surface by residual chlorine atoms. To prevent the corrosion, the $SF_6$ plasma treatment subsequent to the etch has been carried out. A passivation layer is formed by fluorine-related compounds on etched Al-Cu alloy surface after $SF_6$ treatment, and the layer suppresses effectively the corrosion on the surface as the RF power of $SF_6$ treatment increases. The corrosion could be suppressed successfully with $SF_6$ treatment in the RF power of 150watts.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1286-1290
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• 2004

This paper describes the anti-corrosion system on underwater structures of ships. Metals and alloys have several positions in the series such as immunity, corrosion and passivity. The iron potential has to change from the corrosion position to the anodic protection or cathodic protection for preventing corrosion by providing corrosion protection system such as ICCP(Impressed Current Cathodic Protection). The purpose of ICCP system is to eliminate the rusting or corrosion, which occurs on metal immersed in water. The system includes a power supply unit, which consists of a transformer, a converter. a controller, etc. This paper presents the protection performance of ICCP under dynamic condition such as velocity. The variation of potential and current density with time and environment factors are also described Finally, the experimental results will be explained and analysed.

• Corrosion Science and Technology
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• v.3 no.6
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• pp.240-244
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• 2004

Recently a variety of electrochemical techniques have been used for the measurement of under-film corrosion of coated steel. Each method has its own characteristic and is suitable to determine some kinds of anti-corrosive mechanisms of coating film. We developed a new under-film corrosion tester (UFCT) which adoped current interrupter technique in principle. Electrochemical parameters can be measured by UFCT. It is possible for the novel under-film corrosion tester to evaluate under-film corrosion of steel covered with high electric resistance coating film which has no defect and is not easy to evaluate it by other methods. Finally some experimental results of protective coating performance obtained by UFCT were discussed.

• Corrosion Science and Technology
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• v.12 no.3
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• pp.149-157
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• 2013

In corrosion-sensitive areas of exsisting unpainted weathering steel bridges with closed box girder structures. there are some serious local corrosion problems because of rain water or dew water which can not be solved by exsisting maintenance methods. These problems must be controled technically because of bad. influence on the safety of bridge. This study is the first stage of developing the economic corrosion control manual for these local corrosion problems. Through the injection of tar sealant into the crevice of mock-up equipment, it was prooved that the corrosive sealant can be useful to corrosion control at crevice of corrosion sensitive area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.14-20
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• 2012

Performance and anti-corrosion of cold forged fuel pumps and die-casting fuel pumps have been tested in this study. Ethanol with 10 ppm of acetic acid is applied for the anti-corrosion test for 250 hours. Performance test result shows that the pumping efficiency of the cold forged fuel pump is equivalent to that of the die-casting fuel pump. The cold forged lower housing has better quality against corrosiveness and finer metallic structure than the die-casting lower housing does.