Effect of flow rate and SiO2 nanoparticle on dynamic corrosion behavior of stainless steels in molten salt for thermal energy storage

Abstract The effect of SiO2 nanoparticles and flow rate on the corrosion behaviors of 304 and 316 L stainless steels in quaternary nitrate-nitrite (QNN) molten salt are comparatively investigated. The results show corrosion of 304 and 316 L specimens in QNN with nanoparticles are lower than that in QNN. Compared to the corrosion weight loss (mmass) in QNN with nanoparticles, the mmass of 304 and 316 L in QNN is separately increased by 25.2% and 60.4% at 2 m/s after 1000 h due to the sedimentation of the nanoparticles. Besides, the mmass of 304 and 316 L specimens in nanofluids at 2 m/s are individually 16.8% and 13.8% higher than those at 0.6 m/s. The flow rate can rarely affect the types of oxidation products from XRD analysis. Meanwhile, the Rdepth of 316 L specimens is 58.1% lower than that of 304 specimens at 2 m/s in QNN salts-based nanofluids after 1000 h test. This work could provide basic dynamic corrosion data for design and operation of concentrated solar power plants.