한국부식방식학회

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돌리를 이용한 도막 부착력 시험의 영향 인자에 관한 연
Establishment of adhesion strength measurement procedure for marine epoxy coatings was conducted in order to ensure reliability of the test results. It was found that (1) the increase in thickness of the substrates would induce increase of pull-off strength. Especially, the increase in adhesion strength with the substrate thickness increment was attributed to the transition of stress mode to the pure tensile mode excluding bending effect. (2) The longer curing time, the higher pull-off strength. It may be due to higher cross-linking density of the coating (3) The pull-off strength increases as coating thickness increases due to the diminishment of bending effect (4) The longer drying time after water immersion, the higher pull-off strength. It may
be due to the evaporation of water molecule at the coating-substrate interface.
KEYWORDs : coating, pull-off strength, epoxy, polyamide
AUTHORs : 백 윤 호†·손 성 모·박 충 서

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다양한 금속 부품의 내식성 향상을 위한 Zn-Al 열 확산 코팅 기술 개발
Modern industry has a wide variety of application areas such as ocean industry, construction and automobile industry. With the current circumstances, the need for anti-corrosion technology that can be used on materials to withstand in harsh environments, is increasing. In this study, we have sought to develop a metal coating
technology with zinc and aluminum powders as a potential anti-corrosion material. To make a coating on metal products, a thermal diffusion coating method was used under the conditions of 350℃ for 30 minutes. Optical microscope, Field emission scanning electron microscope (FE-SEM&EDX) and X-ray diffraction analysis were used to analyze a coating layer. As a result, we have confirmed that the generated amount of rust on metal parts coated with thermal diffusion coating method decreased dramatically compared with non-coated metal parts. Furthermore, the anti-corrosion performance was evaluated according to the different ratio of zinc and aluminum. Finally, we confirmed the possibility of application and commercialization
of our coating technique on metal parts used in harsh industrial based on the results of these performance.
KEYWORDs : anti-corrosion, metal products, Zinc-Aluminum, thermal diffusion coating
AUTHORs : 이 주 영·이 주 형·황 준·이 용 규†

Page : 178 - 185 DOWNLOAD
Ni-Cr계 고용강화형 합금에서 조성에 따른 기계적 및 고온부식 특성 평가
Alloy 617 is considered as a candidate Ni-based superalloy for the intermediate heat exchanger (IHX) of a very high-temperature gas reactor (VHTR) because of its good creep strength and corrosion resistance at high temperatures. Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. As the Alloy 617 has been exposed to high temperatures at 950°C in the impure helium environment of a VHTR, the degradation of material is accelerated and mechanical properties decreased. The high-temperature strength, creep, and corrosion properties of the structural material for an IHX are highly important to maintain the integrity in a harsh environment for a 60 year period. Therefore, an alloy superior to alloy 617 should be developed. In this study, the mechanical and high-temperature corrosion properties for Ni-Cr alloys fabricated in the laboratory were evaluated as a function of the grain boundary strengthening and alloying elements. The ductility increased and decreased by increasing the amount of Mo and Cr, respectively. Surface oxide was detached during the corrosion test, when Al was not added to alloy. However the alloy with Al showed improved oxide adhesive property without significant degradation and mechanical property. Aluminum seems to act as an anti-corrosive role in the Ni-based alloy.
KEYWORDs : VHTR, Ni-Cr alloy, tensile test, high-temperature corrosion, alloying element
AUTHORs : 정 수 진†·김 동 진

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Ni-Cr계 고용강화형 합금에서 조성에 따른 기계적 및 고온부식 특성 평가
Alloy 617 is considered as a candidate Ni-based superalloy for the intermediate heat exchanger (IHX) of a very high-temperature gas reactor (VHTR) because of its good creep strength and corrosion resistance at high temperatures. Helium is used as a coolant in a VHTR owing to its high thermal conductivity, inertness, and low neutron absorption. However, helium inevitably includes impurities that create an imbalance in the surface reactivity at the interface of the coolant and the exposed materials. As the Alloy 617 has been exposed to high temperatures at 950°C in the impure helium environment of a VHTR, the degradation of material is accelerated and mechanical properties decreased. The high-temperature strength, creep, and corrosion properties of the structural material for an IHX are highly important to maintain the integrity in a harsh environment for a 60 year period. Therefore, an alloy superior to alloy 617 should be developed. In this study, the mechanical and high-temperature corrosion properties for Ni-Cr alloys fabricated in the laboratory were evaluated as a function of the grain boundary strengthening and alloying elements. The ductility increased and decreased by increasing the amount of Mo and Cr, respectively. Surface oxide was detached during the corrosion test, when Al was not added to alloy. However the alloy with Al showed improved oxide adhesive property without significant degradation and mechanical property. Aluminum seems to act as an anti-corrosive role in the Ni-based alloy.
KEYWORDs : VHTR, Ni-Cr alloy, tensile test, high-temperature corrosion, alloying element
AUTHORs : 정 수 진†·김 동 진

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Effects of surface modification with hydroxyl terminated polydimethylsiloxane on the corrosion protection of polyurethane coating
Polyurethane coating was designed to give a hydrophobic property on its surface by modifying it with hydroxyl terminated polydimethylsiloxane and then effects of surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified polyurethane coating were examined using FT-IR/ATR spectroscopy, contact angle measurement and electrochemical impedance test. As results, the
surface of polyurethane coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between polyurethane and modifier by the modification. The phase separation tendency is more appreciable when modified by polydimethylsiloxane with higher content. Water transport
behavior of the modified polyurethane coating decreased more in that with higher hydrophobic surface property. The decrease in the impedance modulus |Z| at low frequency region in immersion test for polyurethane coatings was associated with the water transport behavior and surface hydrophobic properties of modified
polyurethane coatings. The corrosion protectiveness of the modified polyurethane coated carbon steel generally increased with an increase in the modifier content, confirming that corrosion protectiveness of the modified polyurethane coating is well agreed with its water transport behavior.
KEYWORDs : polysiloxane, corrosion protection, EIS, polyurethane, FT-IR
AUTHORs : Jae Hong Jeon and MinYoung Shon†

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The study on the influence of surface cleanness and water soluble salt on corrosion protection of epoxy resin coated carbon steel
The corrosion resistance of epoxy-coated carbon steel was evaluated. The carbon steel surface was subjected to different treatment methods such as steel grit blasting and power tool treatment as well as contamination of water soluble salt. To study the effect of the surface treatments and contamination, the topology of the treated surface was observed by confocal microscopy and a pull-off adhesion test was conducted. The corrosion resistance of the epoxy-coated carbon steel was further examined by electrochemical impedance spectroscopy (EIS) combined with immersion test of 3.5 wt% of NaCl solution. Consequently, the surface contamination by sodium chloride with 16 mg/m2, 48 mg/m2 and 96 mg/m2 didn’t affect the adhesion strength for current epoxy coated carbon steel and blister and rust were not observed on the surface of epoxy coating contaminated by various concentration of sodium chloride after 20 weeks of immersion in 3.5 wt% NaCl aqueous solutions. In addition, the results of EIS test showed that the epoxy-coated carbon steel treated
with steel grit blasting and power tool showed similar corrosion protection performance and surface cleanness such as Sa 3 and Sa 2.5 didn’t affect the corrosion protectiveness of epoxy coated carbon steel.
KEYWORDs : EIS, epoxy, blasting, hygrothermal, blister
AUTHORs : MinYoung Shon†

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