E. A. Karfidov, Yu. P. Zaikov, E. V. Nikitina, K. E. Seliverstov.
ABSTRACT
Experiments were carried out to determine the corrosion rate of stainless steel AISI 316 in a fluoride melt with different concentrations of O2– (by adding lithium oxide to the melt in the concentration range from 0 to 5 wt %). The corrosion rate decreases by an order of magnitude at an oxygen anion concentration in the melt from 0.2 to 0.4 wt %, which may indicate the detection of the phenomenon of high-temperature passivation of the material due to the modification of the composition of the fluoride melt and a decrease in its corrosion activity. In addition, the type of intergranular and pitting corrosion typical of stainless steels in fluoride melts, which is the most dangerous from the point of view of the structural reactor material, changes to continuous when lithium oxide is added due to the “healing” of individual corrosion centers with excess oxygen-containing compounds. The formation of a protective layer of the spinel type with a thickness of 1 μm was established.
KEYWORDS
corrosion, candidate materials for LSR, alkali metal halide melt, high-temperature passivation, spinel-type oxides
DOI: 10.31857/S0235010622040065
EDN: DHSZUO