Corrosion Behavior of Ni 200 and Ni-base Alloys in Hot Lithium Molten salt

Abstract

In the development of the advanced spent fuel management process based on the molten salt technology, it is essential to choose the optimum material for the process equipment handling molten salt. Corrosion behavior of Ni 200 and Ni-base alloys in molten salt of LiCl-<TEX>$Li_2$</TEX>O under oxidation atmosphere was investigated in the temperature range of <TEX>$650～800^{\circ}C$</TEX> for 24～312 hrs. The order of corrosion rate was Ni 200 > Inconel 690 > Inconel 601 > Inconel 600. Inconel 600 alloy showed the highest corrosion resistance among the examined alloys, but Ni 200 exhibited the highest corrosion rate. Corrosion products of Inconel 600 and Inconel 601 were <TEX>$Cr_2$</TEX><TEX>$O_3$</TEX> and <TEX>$NiFe_2$</TEX><TEX>$O_4$</TEX>. In case of Inconel 690, a single layer of <TEX>$CrO_2$</TEX><TEX>$O_3$</TEX> was formed in the early stage of corrosion and an outer layer of <TEX>$NiFe_2$</TEX>O<TEX>$_4$</TEX> and inner layer of <TEX>$Cr_2$</TEX><TEX>$O_3$</TEX> were formed with increase of corrosion time. Inconel 600 showed local corrosion behavior and Inconel 601, 690 showed uniform corrosion behavior.