Accelerated Corrosion of Stainless Steels with the Presence of Molten Carbonates below 923 K

Abstract

The high-temperature corrosion of stainless steels (SUS316L and SUS310S) in the presence of lithium-potassium eutectic carbonate and lithium-sodium eutectic carbonate has been studied by thermogravimetry and the metal consumption method under a carbon dioxide–oxygen atmosphere in the temperature range of 773–1123 K. Although the corrosion of SUS310S obeyed the parabolic rate law for all reaction conditions, the corrosion of SUS316L significantly depended on the reaction conditions. At or above 923 K, the corrosion of SUS316L obeyed the parabolic rate law, even with a carbonate coating. The corrosion rates were accelerated during the initial period of corrosion tests below 923 K, especially around 823 K with a lithium-sodium carbonates coating. The initial accelerated corrosion was a local corrosion, which produced through holes in the metal specimens, and occurred more clearly at higher carbon dioxide partial pressures with the lithium-sodium carbonate coating than with the lithium-potassium carbonate coating.

Solutions for Material Corrosion Problems in MCFC

“…Parallel corrosion studies on stainless steels indicated that the (Li 0.52 Na 0.48 ) 2 CO 3 electrolyte is slightly less corrosive as compared to the standard one probably due to formation of dense oxide scales with less spallation or cracks [13]. However, a more temperature-sensitive corrosion behavior was reported in the (Li 0.52 Na 0.48 ) 2 CO 3 electrolyte with some accelerated corrosion observed during initial periods at temperatures lower than 600°C [19,20]. This could be explained by assuming a larger dependence of the lithiation reactions on temperature in the (Li 0.52 Na 0.48 ) 2 CO 3 electrolyte.…”

Electrochemical Impedance and Modelling Studies of the Corrosion of Three Commercial Stainless Steels in Molten Carbonate

“…The lithiation process is one of the reasons for the electrolyte loss during the operating time of an MCFC [19,20] and, more importantly, this process will change the properties of the scales of stainless steel under thin film of molten carbonate [21][22][23][24]. The corrosion of stainless steel in the cathode compartment or the immersion corrosion will last longer times than thin-film corrosion, so longer testing would be required to study the whole process.…”

The role of temperature on the corrosion and passivation of type 310S stainless steel in eutectic (Li+K) carbonate melt

“…After long test periods, the two-layered structure of the passive scale consists of an external LiFeO 2 layer and an inner Cr-rich oxide layer. The passivity of stainless steels depends on the stability of this inner layer [1,2]. In the case of the high-Cr type 310S steel (ca.…”

“…For instance, the authors of Refs. [2,4] report that the corrosion of 316L steel becomes highly sensitive on the reaction conditions in the eutectic Li + Na carbonate melt during cell start-up. At temperatures as low as 600 • C this steel seems to become highly susceptible to corrosion damage with a pittinglike attack in high CO 2 gases.…”