Journal of the Korean Crystal Growth and Crystal Technology (한국결정성장학회지)

The Korea Association of Crystal Growth (한국결정성장학회)
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Thermal stability of surface modified Ni-Cr-alloys in molten FLiNaK salt

표면처리된 Ni-Cr계 합금의 FLiNaK 용융염 하에서의 고온 안정성

  • Kwang, Hyun Cho (Department of Nanomechatronics Engineering, Pusan National University) ;
  • Bang, Hyun (Division of Mechanical and Energy Systems Engineering, Korea Maritime University) ;
  • Lee, Tae Suk (Department of Materials Engineering, Korea Maritime University) ;
  • Lee, Byeong Woo (Department of Materials Engineering, Korea Maritime University)
  • 조현 (부산대학교 나노메카트로닉스공학과) ;
  • 방광현 (한국해양대학교 기계에너지시스템공학부) ;
  • 이태석 (한국해양대학교 재료공학과) ;
  • 이병우 (한국해양대학교 재료공학과)
  • Received : 2012.09.19
  • Accepted : 2012.10.12
  • Published : 2012.10.31
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Abstract

Inconel 617 and Hastelloy X are the most promising candidate materials for the heat exchanger of next generation nuclear reactor. Surface coating and its effects on high temperature properties for the Inconel 617 and Hastelloy X under molten FLiNaK (LiF-NaF-KF) salt environment have been investigated. For TiAlN and $Al_2O_3$ overlay coatings, the two different PVD (physical vapor deposition) methods of an arc discharge and a sputtering were applied, respectively. A study for the thermal stability of the surface modified Ni-Cr alloy substrates has been conducted. To evaluate the corrosion mechanism of Ni-Cr alloys in the molten salt, a ruptured Inconel pipe used for the molten salt transportation has been analyzed. The thermal properties of morphological and structural properties each sample were characterized before and after heat-treatment at $600^{\circ}C$ in molten FLiNaK salt. The results showed that the TiAlN and $Al_2O_3$ overlay coated specimens had the enhanced high temperature stability.

차세대 원자력발전용 고온 열교환기 소재로 이용될 가능성이 높은 Ni-Cr계 고온합금인 Inconel 617과 Hastelloy X의 표면처리에 따른 FLiNaK(LiF-NaF-KF) 용융염 하에서의 고온물성에 대한 연구를 수행하였다. Inconel 617과 Hastelloy X기판 상에 각각 PVD인 arc discharge 및 sputtering법에 의해 TiAlN 및 $Al_2O_3$ 박막을 코팅 하였다. 이러한 표면처리가 이들 합금의 FLiNaK 용융염 하 고온 안정성에 미치는 영향에 대해 연구하였다. 용융염 하 Ni-Cr계 고온합금의 부식 원리를 이해하기 위해, 용융염 수송 loop에 사용 중 파단된 Inconel 파이프에 대한 미세구조 분석을 수행하였다. 표면처리 된 합금들을 $600^{\circ}C$ 용융염 내에서 열처리 하였으며, 열처리 전후 시편들에 대해 상형성, 미세구조 등 고온 물성 변화를 측정하였다. 연구결과 코팅되지 않은 경우 보다 TiAlN 및 $Al_2O_3$ 박막이 코팅된 소재에서 보다 우수한 고온 안정성을 보여주었다.

Keywords

References

  1. Next generation nuclear plant materials research and development program plan, INL/EXT-06-11701, Rev. 4 (2007).
  2. D.F. Williams, Assessment of candidate molten salt coolants for the NGNP/NHI heat-transfer loop, ORNL/TM-2006/69 (2006).
  3. D.F. Williams, L.M. Toth and K.T. Clarno, "Assessment of candidate molten salt coolants for the advanced high-temperature reactor (AHTR)", ORNL/TM-2006/12 (2006).
  4. M. Shindo and H. Nakajima, "Evaluation of $Al_{2}O_{3}$ and TiN coating on Hastelloy XR alloy under aggressive conditions", ISIJ Int. 29 (1989) 793. https://doi.org/10.2355/isijinternational.29.793
  5. K.A. Gruss and R.F. Davis, "Adhesion measurement of zirconium nitride and amorphous silicon carbide coatings to nickel and titanium alloys", Surf. Coat. Technol. 114 (1999) 156. https://doi.org/10.1016/S0257-8972(99)00042-0
  6. H. Cho, D.M. Lee, J.H. Lee, K.H. Bang and B.W. Lee, "Thermal oxidation behavior of ceramic-coated Ni-Crbase superalloys", Surf. Coat. Tech. 202 (2008) 5625. https://doi.org/10.1016/j.surfcoat.2008.06.094
  7. B.W. Lee, J.C. Park, M.R. Kim, J. H. Koo, B.I. Kim and H. Cho, "The effect of TiCrN coating on high temperature stability of Inconel 617", J. Kor. Cryst. Grow. and Cryst. Tech. 21 (2011) 235. https://doi.org/10.6111/JKCGCT.2011.21.6.235
  8. C.H. Jang, D.J. Lee and D.J. Kim, "Oxidation behavior of an Alloy 617 in very high-temperature air and helium environments", Int. J. Press. Vess. and Piping 85 (2008) 368. https://doi.org/10.1016/j.ijpvp.2007.11.010
  9. C. Cabet and F. Rouillard, "Corrosion of high temperature metallic materials in VHTR", J. Nucl. Mater. 392 (2009) 235. https://doi.org/10.1016/j.jnucmat.2009.03.029
  10. H. Cho and B.W. Lee, "High Temperature properties of surface-modified Hastelloy X alloy", J. Kor. Cryst. Grow. and Cryst. Tech. 22 (2012) 183. https://doi.org/10.6111/JKCGCT.2012.22.4.183
  11. L.C. Olson, C. Luke, J.W. Ambrosek, K. Sridharan, M.H. Anderson, H. Mark and T.R. Allen, "Materials corrosion in molten LiF-NaF-KF salt", J. Fluorine Chem. 130 (2009) 67. https://doi.org/10.1016/j.jfluchem.2008.05.008
  12. P.F. Peterson, H. Zhao and G. Fukuda, "Comparison of molten salt and high-pressure helium for the NGNP intermediate heat transfer fluid", UCBTH-03-004 (2003).
  13. F. Carre, P. Yvon and P. Chaix, "Innovative reactor systems and requirements for structural materials", OECD NEA NSC Workshop on Structural Materials for Innovative, Karlsruhe, Germany (2007).
  14. J.W. Koger, "Evaluation of Hastelloy N alloys after nine years exposure to both a molten fluoride salt and air at temperatures from 700 to 560${^{\circ}C}$", ORN L-TM-4189 (1972).
  15. I. Ozeryanaya, "Corrosion of metals by molten salts in heat-treatment processes", Met. Sci. Heat Treat. 3 (1985) 184.
  16. H. Cho, K.H. Bang and B.W. Lee, "Thermal properties of the surface-modified Inconel 617", J. Kor. Cryst. Grow. and Cryst. Tech. 19 (2009) 298.
  17. T. Watanabe, M. Kondo, T. Nagasaka and A. Sagara, "Corrosion characteristic of AlN, $Y_{2}O_{3}$, $Er_{2}O_{3}$ and$Al_{2}O_{3}$ in Flinak for molten salt blanket system", J. Plasma Fusion Res. 9 (2010) 342.