• 한국해양공학회지
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• 제25권6호
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• pp.56-59
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• 2011

The demand for cold rolled steel (CR) for structural members is gradually increasing. If no surface treatment (coating for corrosion resistance) for CR is conducted, its use is very limited because CR is vulnerable to corrosion. Therefore, we need to develop a coating solution to provide high corrosion resistance for CR. In this study, an organic/inorganic coating solution with Si and Ti (Si polysilicate 7 wt.% + Urethane 13 wt.% + Ti amorphous 0.5 wt.%; LR-0727(1)) was used to evaluate the corrosion resistance of CR under a salt spray test. The specimens with the LR-0727(1) coating were heat treated in a drying oven at $120{\sim}210^{\circ}C$for 5 min. The corrosion resistance was investigated using a salt spray test of 7 h. In addition, an adhesive test was conducted. Rust showed under a heat treatment of $150^{\circ}C$, but no vestiges were found over $160^{\circ}C$. The specimens with heat treatment at $160^{\circ}C$ or more did not experience delamination. From these results, it is considered that the temperature limit for optimum heat treatment is $160^{\circ}C$ considering energy efficiency.

• Nuclear Engineering and Technology
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• 제50권2호
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• pp.229-236
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• 2018

Accident-tolerant fuels (ATFs) are currently of high interest to researchers in the nuclear industry and in governmental and international organizations. One widely studied accident-tolerant fuel concept is multilayer cladding (also known as coated cladding). This concept is based on a traditional Zr-based alloy (Zircaloy-4, M5, E110, ZIRLO etc.) serving as a substrate. Different protective materials are applied to the substrate surface by various techniques, thus enhancing the accident tolerance of the fuel. This study focuses on the results of testing of Zircaloy-4 coated with pure chromium metal using the cold spray (CS) technique. In comparison with other deposition methods, e.g., Physical vapor deposition (PVD), laser coating, or Chemical vapor deposition techniques (CVD), the CS technique is more cost efficient due to lower energy consumption and high deposition rates, making it more suitable for industry-scale production. The Cr-coated samples were tested at different conditions ($500^{\circ}C$ steam, $1200^{\circ}C$ steam, and Pressurized water reactor (PWR) pressurization test) and were precharacterized and postcharacterized by various techniques, such as scanning electron microscopy, Energy-dispersive X-ray spectroscopy (EDX), or nanoindentation; results are discussed. Results of the steady-state fuel performance simulations using the Bison code predicted the concept's feasibility. It is concluded that CS Cr coating has high potential benefits but requires further optimization and out-of-pile and in-pile testing.

• 방사성폐기물학회지
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• 제22권1호
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• pp.55-66
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• 2024

In this study, we investigated the suppression of the corrosion of cast iron in a copper-cast iron double-layered canister under local corrosion of the copper layer. The cold spray coating technique was used to insert metals with lower galvanic activity than that of copper, such as silver, nickel, and titanium, between the copper and cast iron layers. Electrochemically accelerated corrosion tests were performed on the galvanic specimens in KURT groundwater at a voltage of 1.0 V for a week. The results revealed that copper corrosion was evident in all galvanic specimens of Cu-Ag, Cu-Ni, and Cu-Ti. By contrast, the copper was barely corroded in the Cu-Fe specimens. Therefore, it was concluded that if an inactive galvanic metal is applied to the areas where local corrosion is concerned, such as welding parts, the disposal canister can overcome local or non-uniform corrosion of the copper canister for long periods.

• 한국압력기기공학회 논문집
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• 제19권2호
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• pp.102-108
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• 2023

A Chloride-induced stress corrosion cracking (CISCC) of austenite stainless steel in dry cask storage system (DCSS) can occur with extending service time than originally designed. Cold spray coating (CSC) not only form a very dense microstructure that can protect from corrosive environments, but also can generate compressive stress on the surface. This characteristic of CSC process is very helpful to increase the resistance for CISCC. CSC with several powders, such as 304L, 316L and Ni can be optimized to form very dense coating layer. In addition, the impact energy generated as the CSC powder collides with the surface of base metal at a speed of Mach 2 or more can remove the residual tensile stress of welding area and serve the compress stress. CSC layers include no oxidation and no contamination with under 0.2% porosity, which is enough to protect from the penetration of corrosive chloride. Therefore, the CSC coating layer can be accompanied by a function that can be disconnected from the corrosive environment and an effect of improving the residual stress that causes CISCC, so the canister's CISCC resistance can be increased.

• 대한금속재료학회지
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• 제46권5호
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• pp.321-327
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• 2008

Cu based amorphous ($Cu_{54}Zr_{22}Ti_{18}Ni_6$) coating was produced by cold spraying as a new fabrication process. The microstructure and macroscopic properties of amorphous coating layer was investigated and compared with those of cold sprayed pure Cu coating. Amorphous powders were prepared by gas atomization and Al 6061 was used as the substrate plate. X-ray diffraction results showed that Cu based amorphous powder could be successfully deposited by cold spraying without any crystallization. The Cu based amorphous coating layer ($300{\sim}400{\mu}m$ thickness) contained 4.87% porosity. The hardness of Cu based amorphous coating represented $412.8H_v$, which was correspond to 68% of the hardness of injection casted bulk amorphous material. The wear resistance of Cu based amorphous coating was found to be three times higher than that of pure Cu coating. The 3-point bending test results showed that the adhesion strength of Cu based amorphous coating layer was higher than that pure Cu coating. It was also observed that hard Cu base amorphous particle could easily deform soft substrate by particle collisions and thus generated strong adhesion between coating and substrate. However, the amorphous coating layer unexpectedly represented lower corrosion resistance than pure Cu coating, which might be resulted from the higher content of porosity in the cold sprayed amorphous coating.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.557-566
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• 2011

A cold spray coating (CSC) of copper was studied for its application to a high-level radioactive waste (HLW) disposal canister. Several copper coatings of 10 mm thick were fabricated using two kinds of copper powders with different oxygen contents, and SS 304 and nodular cast iron were used as their base metal substrates. The fabricated CSC coppers showed a high tensile strength but were brittle in comparison with conventional non-coating copper, hereinafter defined to as "commercial copper". The corrosion behavior of CSC coppers was evaluated by comparison with commercial coppers, such as extruded and forged coppers. The polarization test results showed that the corrosion potential of the CSC coppers was closely related to its purity; low-purity (i.e., high oxygen content) copper exhibited a lower corrosion potential, and high-purity copper exhibited a relatively high corrosion potential. The corrosion rate converted from the measured corrosion current was not, however, dependent on its purity: CSC copper showed a little higher rate than that of commercial copper. Immersion tests in aqueous HCl solution showed that CSC coppers were more susceptible to corrosion, i.e., they had a higher corrosion rate. However, the difference was not significant between commercial copper and high-purity CSC copper. The decrease of corrosion was observed in a humid air test presumably due to the formation of a protective passive film. In conclusion, the results of this study indicate that CSC application of copper could be a useful option for fabricating a copper HLW disposal canister.

• 동력기계공학회지
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• 제19권5호
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• pp.38-44
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• 2015

The cold-rolled steel sheet for automobile is liable to corrosion, and will be painting in a variety of ways for the anticorrosive. This paper was coated on cold rolled steel (SPCC and SPFC590) for automobiles using five kinds of organic/inorganic hybrid solution. This was evaluated corrosion resistance and so on by the salt spray. Corrosion area was less according to increasing of curing time in 2 types of steel plate with 5 types of the coating solution. No.1 solution was showed the best corrosion resistance regardless of the kinds of the steel sheet. It is judged that the melamin hardner had the role of bridge between $SiO_2$ polysilicate and urethan resin. Other properties were excellent in all solution.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.807-810
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• 2005

In this study, MMA-modified paste of coating material for protecting the concrete structures was developed. The coating material was applied to cement concrete specimens by brush, roller and spray in each of which one, two and three layers to survey, by the cold-hot iterative test, the neutralization test, the chloride ion permeation test and the ante-abrasion test, the affect of painting methods and layers influencing on the durability of coating material. Results of the cold-hot iterative test showed that, regardless of the painting methods and layers, the defects such as crack or fuzz on surface were not produced. As the number of painting layers increased, the neutralization prevention as well as the chloride ion permeation prevention effects were increased. On the other hand, no difference was found between the painting methods. Reducing weight by abrasion of polymer paste coating material was $20\%$ comparing to that of cement mortar.

• Archives of Metallurgy and Materials
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• 제65권3호
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• pp.1011-1014
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• 2020

Ice formed on radome surfaces causes communication disruption due to radio-frequency interference (RFI), which reveals the importance of de-icing systems for radomes. As a radome de-icing application, in this work, carbon nanotube (CNT) thin films were fabricated using a spray-coating method, and influence of process parameters on RF transmittance and electrothermal properties was investigated. With the increase of spraying time, sheet resistance of the fabricated film decreases, which results in a decrease of the RF transmittance and improvement of the heating performance. Also, the de-icing capability of the fabricated CNT film was evaluated at -20℃, and efficient removal of ice under cold conditions was demonstrated.

• 대한기계학회논문집A
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• 제36권4호
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• pp.405-412
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• 2012

종래 아연의 부식 속도를 줄이는 가장 일반적인 방법은 $Cr^{+6}$를 도포하여 화학적으로 개조하는 것이었다. 그러나 $Cr^{+6}$는 현재 환경 보호법 때문에 사용이 제한되어 있다. 따라서 자자들은 Si를 가지는 유/무기 용액에 대한 아연도금강판의 최적 조건을 연구하였다. 최적 내식성은 $190^{\circ}C$에서 5분간 열처리한 조건으로 나타났다. 본 연구에서는 내식성 평가를 위하여 우레탄 용액(Urethane 20 wt.% ; S-700), Si를 가지는 유/무기 용액(Si polysilicate 10 wt.% + Urethane 10 wt.% LR-0317) 및 Si와 Ti를 가지는 2종류의 유/무기 용액(Si polysilicate 7 wt.% + Urethane 13 wt.% + Ti amorphous 0.5 wt.% ; LR-0727(1), Si polysilicate 7 wt.% + Urethane 7 wt.% + Ti amorphous 0.5 wt.% + epoxy 6wt.% ; LR-0727(2))을 사용하였다. 내식성 평가는 냉간압연 강판을 사용하여 염수분무 시험으로 실시하였다. 7시간의 염수 분무 시험에서 LR-0727(1)과 LR-0727(2) 용액이 냉간 압연 강판에 대하여 우수한 내식성을 나타내었다.