The corrosion resistance of 316 stainless steel (316SS) in molten KCl-MgCl₂ salts was studied through static immersion corrosion at high temperatures. Below 600 °C, the corrosion rate of 316SS increased slowly with increasing temperature. When the salt temperature rises to 700 °C, the corrosion rate of 316SS increases dramatically. The corrosion of 316SS is mainly due to the selective dissolution of Cr and Fe at high temperatures. The impurities in molten KCl-MgCl₂ salts could accelerate the dissolution of Cr and Fe atoms in the grain boundary of 316SS, and purification treatment can reduce the corrosivity of KCl-MgCl₂ salts. Under the experimental conditions, the diffusion rate of Cr/Fe in 316SS changed more with temperature than the reaction rate of salt impurities with Cr/Fe.

In this work, a novel eutectic nitrate molten salt mixture of the NaNO₃-KNO₃-Ca(NO₃)₂ (16:48:36 wt%) ternary system with the significant advantage of low melting temperature was successfully designed and prepared using the static fusion method. Then, its thermal-physical properties, such as the melting point, fusion enthalpy, thermal stability, specific heat capacity, thermal diffusivity, thermal conductivity, density, and viscosity, were respectively measured by a modified or self-developed experimental device. Meanwhile, for better understanding and evaluating the heat transfer and storage performances of the material, the thermal-physical properties of this studied molten salt were further compared with those of other currently potential nitrate/nitrite systems in concentrating solar power (CSP) applications. The results proved that the newly developed NaNO₃-KNO₃-Ca(NO₃)₂ system has excellent thermal-physical properties and flow characteristics. Moreover, the cost analysis also showed the new salt has good economic performance with potential market competitiveness, its price is determined to be only 42.48 ¥/kg. All of these advantages make it a promising candidate material for heat transfer fluid (HTF) and thermal energy storage (TES) in CSP applications. This work is useful and significant for developing new molten salt materials and choosing appropriate media of HTF and TES in CSP plants or other probable thermal power generation facilities.

The corrosion behaviours of Ni-Mo-Cr alloy and 316 stainless steel samples after immersing in NaCl-KCl-AlCl₃ salt at 400.0°C for 168 h were investigated. The surface of Ni-Mo-Cr alloy basically kept its pre-corrosion morphology, with only a few corrosion pits. While NaCl-KCl-AlCl₃ salt had stronger corrosivity to 316SS. After corrosion, the grain boundary of the surface of 316SS alloy was clearly visible, and the Fe and Cr atoms on the surface of 316SS were selectively corroded, leaving a Ni- rich layer of about 6.5 µm on the outmost surface of 316SS. At the temperature of 400.0°C, the corrosion resistance of Ni-Mo-Cr alloy to molten NaCl-KCl-AlCl₃ salt was better than that of 316SS.

The corrosion behavior of GH3535 alloys in KCl–MgCl₂ eutectic salts with or without magnesium (Mg) was investigated using the static immersion tests. The effect of purification treatment on the corrosion of GH3535 specimens was also evaluated by the different analysis. The KCl–MgCl₂ salts purified with Mg and reducing service temperature can slow down the corrosion rate of GH3535 specimens. Infrared spectra results showed that purification treatment reduced the content of crystal water in the KCl–MgCl₂ salts. The difference of hydrate content in KCl–MgCl₂ salts and the diffusion rate of Cr in alloy are the main reasons for the change of GH3535 specimens corrosion rate.