Corrosion behavior of Fe-Cr-Ni alloy in molten LiCl/Li2O-LiCl salts

Soo-Haeng Cho, Young-Joon Shin, Hyun-Soo Park, Jun-Shan Zhang

Korea Atomic Energy Research Institute, P.O.Box 105, Yusong, Taejon, 305-600, Korea

Tel. +82-42-868-2584,  Fax: +82-42-868-8370, e-mail: nshchol@kaeri.re.kr

Dept. of Materials Enginerring, Dalian University of Technology, Dalian 116024, China

 

  In the development of an advaced spent fuel management process based on the molten salt technology, it is necessary to choose the optimum materials for the process piping and equipment handling molten salt. The corrosion behavior of a series of Fe-Cr-Ni alloy, which is manufactured by the korea Atomic Energy Research Institute, in the molten salts of LICl and LiCl-25%Li2O has been investigated in the temperature range of 650-850C. In the molten LiCl salt, a dense protective scale of LiCrO2 was formed in according to the type of parabolic oxidation kinetics and the corrosion rate was controlled by the diffusion of Cr across the protective scale from substrate to scale/salt interface. Otherwise in the system of molten LiCl-25%Li2O salt, the non-protective porous scale of LiCrO2 and Ni was formed instead of the LiCrO2 protective scale. Due to the Li2O-induced basic fluxing mechanism of protective oxide of Cr2O3, the corrosion rate of the alloy in the mixed molten salt of LiCl-25%Li2O was significantly higher than that in the molten LiCl salt. At the dilute oxygen concentration of gas phase and the high con centration of lithium oxide in the salt phase, it was revealed that Cr was preferentially oxidized in the mixed molten salt system of LiCl-25%Li2O. The corrosion rate of the alloy was increased with the increase in Cr content.