• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.292.2-292
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• 2002

• Journal of Welding and Joining
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• 제19권1호
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• pp.95-103
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• 2001

The properties of the detonation sprayed cermet coating are investigated through the mechanical, corrosion and erosion test. The test results are also compared with the properties of the substrate materials, STS 329J1, dual phase stainless steel and the plasma sprayed cermet coatings. The two kinds of carbide cermet power, WC+NiCr, Cr$_3$C$_2$+NiCr were used in this experiment. The experimental results showed that the anti-corrosive and anti-erosive properties of the detonation sprayed cermet coatings are superior to the plasma sprayed cermet coatings. The WC+NiCr cermet coating appears to be more effective than Cr$_3$C$_2$+NiCr cermet coating in abrasive erosion environment, whereas the Cr$_3$C$_2$+NiCr cermet coatings are more effective in cavitation erosion environment.

• Corrosion Science and Technology
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• 제13권4호
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• pp.145-151
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• 2014

The objectives of this study are to investigate the effect of the concentration ratios of Ni and Fe ions on crud deposition onto the fuel cladding surface in the simulated primary environments of a pressurized water reactor. Crud deposition tests were conducted in the Ni and Fe concentration ratios of 20:20 ppm, 39:1 ppm and 1:39 ppm at $325^{\circ}C$ for 14 days. In the case of the same Ni and Fe ion ratio (20:20), nickel ferrite with a polyhedral shape was formed. Nickel oxide deposits with a needle shape were formed in the condition of high Ni to Fe ion ratio (39:1), While polyhedral iron oxide and needle-like nickel oxide formed in the condition of low Ni to Fe ion ratio (1:39). The amount of deposits increased, when Fe oxides were formed. This indicates that Fe rich oxides stimulated Ni oxide deposition.

• 한국재료학회지
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• 제8권6호
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• pp.571-576
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• 1998

본 연구에서는 용융탄산염 연료전지용 분리판으로서 오스테나이트계 스테인레스강 중, 310S를 사용하여 용융염 전해질 및 양극측 분위기에서 부식거동, 부식생성물의 형성과정 및 기구에 관한 고찰을 실시하였다. 분리판의 부식 진행과정은 부식반응 이후 안정 부식생성물이 형성되기까지 빠른 부식이 진행되는 부식생성물 형성단계와 안정 부식생성물 형성 후 보호파괴가 일어나기 까지의 부식 억제단계, 그리고 보호파괴 이후 부식이 다시 증가되는 부식 진행단계의 3단계 과정을 경유하며 진행하였다. 분리판 내 원소들의 농도분포는 부식생성물 형성영역에서는 Fe가, 부식 방어영역에서는 Cr이, 그리고 Ni은 Cr 고갈영역과 기지 안쪽에서 높게 형성되었다. 또한 양극측에서 분리판은 전해질의 이온화에 의한 부식이 주된 부식기구였으며, 최종 부식생성물은 $LiFeO_2$와 $LiCrO_2$였다.

• 한국표면공학회지
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• 제42권6호
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• pp.280-286
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• 2009

In this study, the corrosion property of copper alloy tubes in seawater has been investigated. Three copper alloys of nominal composition Cu-20Zn-2Al(Al-Brass), Cu-30Ni(CN70/30) and Cu-10Ni(CN90/10) were considered. The samples were immersed in 3%NaCl flowing solution at $90^{\circ}C$ for 30, 50 and 80 days. Corrosion rate of copper alloy tubes in 3%NaCl flowing solution was investigated by weight-loss measurements and electrochemical test. The CN70/30 showed lowest corrosion rate among three copper alloy tubes. Because of passive films formation, corrosion rates of three types of copper tubes were decrease with time. Surface characteristics of copper alloy tubes were analyzed by optical micrograph(OM), scanning electronic microscopy (SEM), energy dispersive X-ray analysis(EDAX) and X-ray diffraction patterns(XRD). CN70/30 showed partly pitting problem on the surface owing to high Fe content, even though having high resistant against corrosion. Cracks appeared on the surface of CN90/10 and CN70/30 after more than 50 days immersion, which could be derived from high nickel contents.

• Nuclear Engineering and Technology
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• 제32권5호
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• pp.514-520
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• 2000

The mechanism of corrosion behavior has to be understood clearly to select an optimum material for handling molten salts to be used in the oxide reduction process of PWR spent fuel. In this study, the oxidation states of corrosion products on the surface of Inconel 600 and 800H as well as their chemical compositions and structural informations were determined by using XPS, ICP-AES, AAS, EPMA and XRD after the corrosion experiment with lithium molten salts at 75$0^{\circ}C$ for 25 hours. Nickel and oxygen were detected from the corrosion products on the surface of Inconel plates and chromium was found to be dissolved out into lithium molten salts leaving cracks on the surface. The corrosion products were identified as metal oxides such as Fe$_2$O$_3$, Cr$_2$O$_3$, NiO, NiFe$_2$O$_4$and MnO by using XPS and XRD.

• Corrosion Science and Technology
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• 제18권1호
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• pp.33-38
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• 2019

Alloy 600/182 with excellent mechanical/chemical properties have been utilized for nuclear power plants. Although both alloys are known to have superior corrosion resistance, stress corrosion cracking failure has been an issue in primary water environment of nuclear power plants. Therefore, primary water stress corrosion crack (PWSCC) growth rate tests were conducted to investigate crack growth properties of Alloy 600/182. To investigate PWSCC growth rate, test facilities including water chemistry loop, autoclave, and loading system were constructed. In PWSCC crack growth rate tests, half compact-tension specimens were manufactured. These specimens were then placed inside of the autoclave connected to the loop to provide primary water environment. Tested conditions were set at temperature of $360^{\circ}C$ and pressure of 20MPa. Real time crack growth rates of specimens inside the autoclave were measured by Direct Current potential drop (DCPD) method. To confirm inter-granular (IG) crack as a characteristic of PWSCC, fracture surfaces of tested specimens were observed by SEM. Finally, crack growth rate was derived in a specific stress intensity factor (K) range and similarity with overseas database was identified.

• 한국재료학회지
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• 제9권10호
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• pp.985-991
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• 1999

Incoloy 800H, KSA (Kaeri Superalloy)-6, Inconel 600 및 Hastelloy C-276 합금의 용융염에서의 부식거동을 650~85$0^{\circ}C$ 온도범위에서 조사하였다. LiCl-Li$_2$O혼합용융염에서의 부식은 Li$_2$O에 의한 염기성 용해 기구에 의해 진행되며, 부식속도가 LiCl에서보다 훨씬 빠르게 나타났다. 혼합용융염 LiCl-Li$_2$O에서는 Ni기 합금의 부식속도가 Fe기 합금보다 빠르고, Mo와 W의 함량이 높은 Hastelloy C-276이 가장 빠른 부식속도를 나타내었다. 용융염 LiCl에서는 LiCrO$_2$의 단일 부식층이 형성되고, LiCl-Li$_2$O 혼합용융염에서는 산화물과 Ni의 2상구조의 다공성 부식층이 형성되었다.

• 한국표면공학회지
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• 제37권5호
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• pp.296-300
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• 2004

The defects of partial denture frameworks are mainly shrinkage porosity, inclusions, micro-crack, particles from investment, and dendritic structure. In order to investigate a good casting condition of partial denture frameworks, the three casting alloys and casting methods were used and detected casting defects were analyzed by using electrochemical methods. Three casting alloys (63Co-27Cr-5.5Mo, 63Ni-16Cr, 63Co-30Cr-5Mo) were prepared for fabricating partial denture frameworks with various casting methods; centrifugal casting (Kerr, USA), high frequency induction casting (Jelenko Eagle, USA), vacuum pressure casting (Bego, Germany). The casting temperature was $1,380^{\circ}C$ (63Co-27Cr-5.5Mo and 63Ni-16Cr) and $1,420^{\circ}C$ (63Co-30Cr-5Mo). The casting morphologies were analyzed using FE-SEM and EDX. The corrosion test of the dendritic structure was performed through potentiodynamic method in 0.9% NaCl solutions at $36.5^{\circ}C$ and corrosion surface was observed using SEM. The defects of partial denture frameworks improved in the order of centrifugal casting, high frequency induction casting, and vacuum pressure casting method, especially, pore defects were found at part of clasp in the case of centrifugal casting method. The structure of casting showed dendritic structure for three casting alloys. In the 63Co-27Cr-5.5Mo and 63Co-30Cr-5Mo, $\alpha$-Co and $\varepsilon$-Co phases were identified at matrix and $${\gamma}$-Ni_2$Cr second phase were shown in 63Ni-16Cr. Also, the corrosion resistance of cast structure increased in the order of vacuum pressure casting, high frequency induction casting, and centrifugal casting method.

• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.536-541
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• 2015

Copper has been used extensively as an electric wire or as a base material in various types of machineries owing to its good electrical and thermal conductivity and good fabricating property, as well as its good corrosion resistance compared to iron. Furthermore, the copper-nickel alloy has significant corrosion resistance in severely corrosive environments. Although, cupro-nickel alloy shows better corrosion resistance than the brass and bronze series, this alloy also corroded in severely corrosive environments, including aggressive chloride ions, dissolved oxygen, and condition of fast flowing seawater. In this study, and annealing treatment at various annealing temperatures was carried out on the cupro-nickel (Cu-10%Ni) alloy, and the effects of annealing were investigated using electrochemical methods, such as measuring the polarization and impedance behaviors under flowing seawater conditions. The corrosion resistance increased by annealing compared to non heat treatment in the absence of flowing seawater. In particular, the sample annealed at $200^{\circ}C$ exhibited the best corrosion resistance. The impedance in the presence of flowing seawater showed higher values than in the absence of flowing seawater. Furthermore, the highest impedances was observed in the sample annealed at $800^{\circ}C$, irrespective of the present of flowing seawater. Consequently, the corrosion resistance of cupro-nickel (Cu-10%Ni) alloy in a severely corrosive environment can be improved somewhat by annealing.