한국부식방식학회

Page : 191 - 197 DOWNLOAD
밀폐 박스거더형 무도장 내후성강 교량의 부식취약부에 대한 방식대책 연구(Ⅱ)
his study is the second stage of developing the corrosion control technical manual about unpainted weathering steel bridge with closed box girder structures.
This paper contains selection of corrosive sealant to apply into crevice of upper flange, injecting test of sealant at mock-up equipment with various condition, evaluation of experiment result.
Through the experiment of injection of sealants into crevice of mock-up equipment, it is proved that the tar sealant injecting corrosion control method is useful to protect corrosion at box girder upper flange corroded by remaning rain water with calcium chloride.
KEYWORDs : unpainted weathering steel, splice connection part, electrochemical corrosion, corrosion sensitive area, multi-function sealant
AUTHORs : 송창영†·이의호·이제현·박현출·최재석·노영태

Page : 185 - 190 DOWNLOAD
전기도금법으로 만든 니켈-티타니아 복합체에서 초음파 처리가 도금층에 미치는 영향 연구
In the present study, Ni-TiO₂composite coatings were electrodeposited in a sulfamate bath containing TiO₂particles. The influence of the ultrasonic treatment on the co-deposition of TiO₂particles in the coating and the hardness of the electrodeposited Ni-TiO₂composite has been investigated. Three different ultrasonic treatments (pretreatment before the electrodeposition (pre-UT), pretreatment + applied during the electrodeposition (UT), and the electrodeposition without the ultrasonic treatment (w/o UT)) were performed. The Ni-TiO₂composite coatings are characterized using scanning electron microscopy (SEM), image analyzer, and hardness tester. Comparison of results indicates that the volume fraction is more important factor than the agglomerated particle size in terms of the strength improvement, and the strength of the electrodeposited Ni-TiO₂composite coatings is enhanced with pre-UT condition.
KEYWORDs : electro-co-deposition, ultrasonic treatment, volume fraction, current efficiency, particle agglomeration
AUTHORs : 김명진†·김정수·김동진·김홍표·황성식

Page : 179 - 184 DOWNLOAD
배관 침부식 손상 연속모사 장비 개발 및 실증
Pipe wall thinning caused by erosion and corrosion can adversely affect the operation of aged nuclear power plants. Some injured workers owing to pipe rupture has been reported and power reduction caused by unexpected pipe damage has been occurred consistently. Therefore, it is important to develop erosion-corrosion damage prediction model and investigate its mechanisms. Especially, liquid droplet impingement erosion(LDIE) is regarded as the main issue of pipe wall thinning management. To investigate LDIE mechanism with corrosion environment, we developed erosion-corrosion damage simulation apparatus and its capability has been verified through the preliminary damage experiment of 6061-Al alloy. The apparatus design has been based on ASTM standard test method, G73-10, that use high-speed rotator and enable to simulate water hammering and droplet impingement. The preliminary test results showed mass loss of 3.2% in conditions of peripheral speed of 110m/s, droplet size of 1mm-diameter, and accumulated time of 3 hours. In this study, the apparatus design revealed feasibility of LDIE damage simulation and provided possibility of accelerated erosion-corrosion damage test by controlling water chemistry.
KEYWORDs : erosion, corrosion, liquid droplet impingement, damage, pipe
AUTHORs : 남원창·류경하†·김재형

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Corrosion characteristics and interfacial contact resistances of TiN and CrN coatings deposited by PVD on 316L stainless steel for polymer electrolyte membrane fuel cell bipolar plates
In a polymer membrane fuel cell stack, the bipolar plate is a key element because it accounts for over 50% of total costs of the stack. In order to lower the cost of bipolar plates, 316L stainless steels coated with nitrides such as TiN and CrN by physical vapor deposition were investigated as alternative materials for the replacement of traditional brittle graphite bipolar-plates. For this purpose, interfacial contact resistances were measured and electrochemical corrosion tests were conducted. The results showed that although both TiN and CrN coatings decreased the interfacial contact resistances to less than 10 mΩ·cm2, they did not significantly improve the corrosion resistance in simulated polymer electrolyte membrane fuel cell environments. A CrN coating on 316L stainless steel showed better corrosion resistance than a TiN coating did, indicating the possibility of using modified CrN coated metallic bipolar plates to replace graphite bipolar plates.
KEYWORDs : Fuel cell, Bipolar plate, Stainless steel, CrN, TiN, PEMFC
AUTHORs : 이재봉†, 오인환

Page : 163 - 170 DOWNLOAD
Determining Factors for the Protectiveness of the Passive Film of FeCrN Stainless Steel Formed in Sulfuric Acid Solutions
In NaCl solutions acidified with H₂SO₄, Fe20Cr1.1N alloy showed enhanced pitting corrosion resistance than Fe20Cr alloy. An XPS analysis revealed that the passive film of Fe20Cr1.1N alloy contained higher cationfraction of Cr than that of Fe20Cr alloy, and nitrogen was incorporated into the film. In addition, it was found that the passive film of Fe20Cr1.1N alloy was thinner and had higher oxygen vacancy density than that of Fe20Cr alloy. Based on these observations, it was concluded that the chemical composition was the determining factor for the protectiveness of the passive film of Fe20Cr based alloy in dilute H₂SO₄ solution.
KEYWORDs : stainless steel, nitrogen, sulfuric acid solution, passive film, Mott-Schottky, XPS
AUTHORs : 하헌영†, 이태호

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