한국부식방식학회

HOME > >

Page : 253 - 258 DOWNLOAD
수산화구리가 전착도막의 경화성과 내식성에 미치는 영향
Effects of copper hydroxide(Ⅱ) on the curing and the corrosion resistance of electrocoating were investigated by MEK rubbing test, electrochemical impedance spectroscopy (EIS) and Thermo-gravimetric analysis (TGA). Curing performance of electrocoating was lowered with increasing the content of copper hydroxide(Ⅱ)
as evidenced by the MEK rub performance which decreased with increasing the content of copper hydroxide(Ⅱ). This indicates copper hydroxide(Ⅱ) affected the blocked isocyanate reaction in the coatings, by the decomposition of copper hydroxide(Ⅱ) to CuO and H2O during reaction of isocyanate with nuclephiles.
Corrosion resistance of coatings also decreased with the content of copper hydroxide. This reflects the higher barrier property in coatings with higher curing performance.
KEYWORDs : cataphoretic coating, copper hydroxide, curing performance, rub test, corrosion resistance,
AUTHORs : 양원석†·황운석

Page : 245 - 252 DOWNLOAD
이종 알루미늄 합금의 로봇 미그 용접 시 용접재료에 따른 기계적 및 전기화학적 특성 평가
In this study, mechanical and electrochemical characteristics with welding material in MIG welded with ROBOT for dissimilar Al alloys were investigated using various experiment methods. The MIG welding by ROBOT with ER5183 and ER5556 for the 5456-H116 and 6061-T6 Al alloy were carried out. The hardness of welding zone was lower than that of base metal. In electrochemical experiment, ER5183 welding material presented excellent characteristics. The yield strength and maximum tensile strength in welding with welding material of ER5183 presented lower value than those of ER5556. The elongation and time-to-fracture showed the opposite results.
KEYWORDs : MIG welding, Al alloy, electrochemical experiment, welding material
AUTHORs : 김성종†·한민수·우용빈

Page : 239 - 244 DOWNLOAD
ALBC3 합금의 쇼트피닝 분사거리에 따른 해수 내 캐비테이션 손상 평가
Marine equipment exposed to harsh environments requires not only excellent corrosion resistance but also improvement of physical characteristics against natural material degradation. With growing interests in ocean energy resources, the higher reliability for marine equipment has become more important in terms of material characteristics. ALBC3 alloy represents excellent corrosion resistance and is widely used in corrosive environments. However, cavitation damage occurs frequently due to its poor durability in high flow rate of marine environment. In this research, shot peening technology was employed as a surface modification with shot peening stand-off distance to mitigate cavitation damage. The effects of shot peening on extent of cavitation damage and weight loss were evaluated for both shot peened and non-peened specimens. The results revealed that the application of shot peeing decreased cavitation damage for all experimental conditions in comparison with the non-peened specimens. The optimum stand-off distance was determined to be 10 cm, since more than 35 % of cavitation damage reduction was observed.
KEYWORDs : :corrosion resistance, cavitation damage, shot-peening, surface modification, stand-off distance
AUTHORs : 한민수·장석기·김종신·김성종†

Page : 233 - 238 DOWNLOAD
ALBC3 합금의 표면 개질을 위한 쇼트피닝 분사거리가 전기화학적 특성에 미치는 영향
In the case of casting materials or ductile materials for marine equipment, it is common to employ a surface modification for achieving cost reduction and improvement in strength. In particular, aluminium bronze ALBC3 exhibits excellent corrosion resistance, and thus widely used for marine application. However, application of the material under high-velocity seawater flow may induce electrochemical corrosion damage and physical damage such as cavitation erosion, leading to shorter service life of equipment.In this study, surface modification was carried out on ALBC3 alloy for different shot peening stand-off distances, and the physical hardness and electrochemical characteristics before and after modification were investigated. The results in each case showed the hardness increase in comparison with non-peened specimen, and the maximum hardness improvement(50 %) was found in 10 cm of shot-peening stand-off distance. It is observed that the electrochemical characteristics were irrelevant to application of shot peening.
KEYWORDs : cast materials, surface modification, electrochemical experiment, shot peening, stand-off distance
AUTHORs : 한민수·현광용·김성종†

Page : 227 - 232 DOWNLOAD
주증기계통 오리피스 후단 소구경 배관의 감육 및 누설 발생
A number of components installed in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), Cavitation, Flashing, and LDIE (Liquid Droplet Impingement Erosion). Those aging mechanisms can lead to thinning of the components. In April 2013, one (1) inch small bore piping branched from the main steam line experienced leakage resulting from wall thinning in a 1,000 MWe Korean PWR nuclear power plant. During the normal operation, extracted steam from the main steam line goes to condenser through the small bore piping. The leak occurred in the downstream of an orifice. A control valve with vertical flow path was placed on in front of the orifice. This paper deals with UT (Ultrasonic Test) thickness data, SEM images, and numerical simulation results in order to analyze the extent of damage and the cause of leakage in the small bore piping. As a result, it is concluded that the main cause of the small bore pipe wall thinning is liquid droplet impingement erosion. Moreover, it is observed that the leak occurred at the reattachment point of the vortex flow in the downstream side of the orifice.
KEYWORDs : liquid droplet impingement erosion, wall thinning, scanning electron microscope, computational fluid dynamic
AUTHORs : 황경모†

Page : 220 - 226 DOWNLOAD
전기화학적 노이즈 저항 측정에서의 불확도 평가
The uncertainty in statistical noise resistance measurement was evaluated for a type 316 stainless steel in NaCl solutions at room temperature. Sensitivity coefficients were determined for measurands or variables such as NaCl concentration, pH, solution temperature, surface roughness, inert gas flow rate and bias potential amplitude. The coefficients were larger for the variables such as NaCl concentration, pH, inert gas flow rate and solution temperature, and they were the major factors increasing the combined standard uncertainty of noise resistance.However, the contribution to the uncertainty in noise resistance measurement from the above variables was remarkably low compared to that from repeated measurements of noise resistance, and thus, it is difficult to lower the uncertainty in noise resistance measurement significantly by lowering the uncertainties related with NaCl concentration, pH, inert gas flow rate and solution temperature. In addition, the uncertainty in noise resistance measurement was high amounting to 17.3 % of the mean, indicating that the reliability in measurement of noise resistance is low.
KEYWORDs : electrochemical noise, noise resistance, uncertainty, sensitivity coefficient
AUTHORs : 김종집†·강수연

Page : 215 - 219 DOWNLOAD
수화과정에서 전처리가 알루미늄 합금의 용출에 미치는 효과
Aluminum alloy(3003) can be dissolved during hydration process with hot tap water. In order to increase the stability of aluminum alloy, it was pretreated with anodization and phosphoric acid before hydration process. The effect of pretreatment on the surface property changes was analyzed with X-ray Photoelectron Spectroscopy (XPS) and Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) and their results supported that the increase of hydroxyl group (-OH) on the surface formed during anodization and phosphorous acid treatment prevented the dissolution of aluminum alloy during hydration process at high temperature.
KEYWORDs : aluminum alloy 3003, hydration, anodization, phosphoric acid, XPS, ICP-OES
AUTHORs : 이병구·이호연·탁용석†

Page : 209 - 214 DOWNLOAD
0.5wt% 탄소강을 이용한 해안 야외부식시험과 염수분무시험,가속부식시험의 가속계수에 대한 연구
In the industry, accelerated corrosion test is used for the life time prediction. When anti-corrosion test proceeds in real environments, it is difficult that we predict and evaluate the corrosion life time because of the long test time such as 10 years or more time. Accelerated corrosion test and Salt spray test are able to test corrosion life time of products in the laboratory instead of outdoor corrosion test. Experimental procedure is selected for the corrosion standard specimen, exposure of the specimens, measurements of the mass loss and evaluating the mass loss data. As a result, the acceleration factor of the accelerated corrosion test to the outdoor corrosion test is 414.8. Therefore we can predict the corrosion life time of carbon steel during a short time period.
KEYWORDs : outdoor corrosion test, salt spray test, accelerated corrosion test, cyclic corrosion test, acceleration factor
AUTHORs : 조의열†·권기봉·조대형·김종렬

Page : 203 - 208 DOWNLOAD
A Study on Kaolin and Titanium dioxide affecting Physical Properties of Electrocoating
The electrocoating for automotive bodies is pigmented with a mixture of titanium dioxide and kaolin. In this study, the effects of titanium dioxide and kaolin contents in coating on electrodeposition process, drying, and surface properties such as surface roughness, gloss, impact resistance and corrosion resistance were investigated. Titanium dioxide and kaolin in coating do not have a decisive effect on curing reaction during drying and corrosion resistance but on gloss, surface roughness, impact resistance and electrodeposition process of coating. According to its size and shape on coating surface, pigment contents increased during drying process. However, the contents of kaolin and TiO2 in coating didn\'t affect the corrosion resistance on zinc phosphated substrate, and the curing properties.
KEYWORDs : titanium dioxide, kaolin, cataphoretic coating, pigment , extention pigment
AUTHORs : 양원석†, 황운석

<
1
>