LiCl-Li2O 용융염에서 초내열합금의 부식거동

Abstract

In this research, the corrosion behavior of super-heat-resistant alloy was studied for developing a reactor vessel material for metal conversion of spent nuclear fuel via lithium molten salt electrolysis. The experimental results are summarized as follows: (1) The oxide formation during corrosion reaction was at the rate of diffusion of alloying elements with the thermodynamic stability according to the oxide formation, and initially formed Fe, Cr-oxide. As the corrosion progressed, Fe, Ni-rich oxide, and Ni-based spinel oxides emerged. (2) The corrosion rate of super-heat-resistant alloys follows the parabolic law for reaction time and linear law for the concentration of Li2O. (3) Al and Ti, which are oxygen-active elements, are useful for improving corrosion resistance; at Al and Ti contents of approximately 1.5% and 2.5% respectively, these alloying elements are the first to be oxidized through external diffusion to form oxides. This may also inhibit internal oxidation through formation of a layer on the oxide/base metal interface. Although Mo and Nb tended to be concentrated at the oxide/oxide interface, a clear improvement in corrosion resistance to internal oxidation could not be observed.