Electrochemical study on the corrosion behavior of 316L stainless steel in quaternary nitrate molten salt nanofluids for thermal energy storage applications

Molten salt nanofluids has been extensively considered for Thermal Energy Storage (TES) applications due to its enhanced heat storage and heat transfer properties. The compatibility between molten salt nanofluids and metal materials becomes a key issue affecting their application in TES systems. In this paper, corrosion tests were carried out on 316 L stainless steel in quaternary nitrate molten salt at 565 °C using electrochemical methods including impedance spectroscopy and potentiodynamic polarization to determine the effect of the addition of nanoparticles to the molten salt corrosion process. The results showed that the addition of nanoparticles reduced the corrosion current density of 316 L stainless steel in quaternary mixed molten salt. The corrosion current density of 316 L stainless steel in molten salt nanofluids with SiO2 and TiO2 was reduced to 0.636 mA/cm2 and 0.749 mA/cm2, respectively. And the EIS results showed that the impedance value of 316 L stainless steel in molten salt nanofluids was significantly larger than that in base salt. The addition of nanoparticles to the molten salt slowed down the ionic transport of 316 L stainless steel in the molten salt and the formation of reticulated and acicular nanostructures enhanced the corrosion resistance of the stainless steel oxide layer. Therefore, the presence of nanoparticles reduces the corrosion of molten salt on stainless steel.