A Corrosion Suppression Coatings for Molten Nitrate Salt

The use of solar energy for power generation provides an efficient sustainable energy solution. Among a number of technologies developed for power generation using solar energy, concentrating solar power (CSP) is encouraging because it makes use of mature technology in the power block. Thermal energy storage (TES) is added to CSP, making it competitive with other power generation technologies and delivering dispatchable energy. Molten salts are one of the materials of choice for the TES. Although the use of molten salts as heat transfer fluid and thermal storage in CSP has various advantages, storage tanks and pipework can be highly susceptible to corrosion. Different approaches have been adopted to suppress corrosion including the use of specialised alloys and high purity molten salts; however, both contribute to a substantial increase in construction and operating costs. In this study, a literature review is provided on coatings to suppress the hot corrosion of the storage vessels and pipework containing molten salts. There has been widespread use of anticorrosion coatings for numerous applications, providing guidelines to develop anticorrosion coatings for TES. Various important factors to be considered for choosing coating material are described herein. To date, several published studies discuss the corrosion resistance of different alloys and coatings for different applications. This study reports on corrosion tests and oxidation tests, while making comparison between different alloys with use of data extracted from literature. Among other materials studied the nickel aluminium alloys exhibit very promising properties as protective coating.