Corrosion effect by preferential formation of Cr and Fe-based ceramic compounds under NaCl–KCl–MgCl2 molten salts |
Jisu Na1, Su Hyeong Kim1, Sung Joong Kim3, Dong-Joo Kim2, Young Soo Yoon1 |
1Department of Materials Science and Engineering, Gachon University, Seongnam-si, Gyeonggi-do, 13120, Republic of Korea 2Materials Research and Education Center, Auburn University, 275 Wilmore Labs, Auburn, AL, 36849, USA 3Department of Nuclear Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea |
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Received: October 30, 2024; Revised: January 27, 2025 Accepted: February 17, 2025. Published online: March 11, 2025. |
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ABSTRACT |
The molten salt reactor (MSR) is a promising next-generation nuclear reactor; the structural materials for MSR must exhibit high corrosion resistance as chemical corrosion can cause structural problems in MSR systems at high temperatures. In this study, the corrosion behaviors of Fe-based stainless steel 316L, Ni-based Hastelloy C-276, and Hastelloy N10003 were observed in NaCl–KCl–MgCl2 molten salt at 800 °C for 48 h. For MgCl2, the strong hygroscopicity affects the corrosion of the alloy. Notable amounts of Cr and Fe depletion were observed in the corrosion-affected layer on the alloy surface for the three alloys that were loaded in the high-temperature molten salt. The cause of corrosion appears to be dominated by the quantities of Ni, Cr, and Fe, which are the main elements constituting the alloys, and the ceramic compounds generated by moisture and impurities. The Fe-based alloy mainly exhibited intergranular corrosion, and the corrosion depth was approximately five times greater than that of the Ni-based alloys. Hastelloy N10003, with a Cr content of 7%, exhibited the best corrosion resistance among the three alloys. However, if Hastelloy N10003 is also used as a long-term MSR structural material, surface modification is required to prevent corrosion. |
Key words:
Molten salt reactor (MSR) · Corrosion resistance · Magnesium chloride hexahydrate · Gibbs free energy · Corrosion Compound |
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