Nanoparticles as a high-temperature anticorrosion additive to molten nitrate salts for concentrated solar power

Abstract Hot corrosion is profoundly detrimental to construction elements in Concentrated Solar Power (CSP) plants affecting their lifetime, running costs and safety. In this work we have studied the anticorrosion effect of TiO2 nanoparticles additives on carbon steel using XRD, XPS with depth profiling, EDX and FIB/SEM techniques. The results revealed that the addition of 1 wt% of TiO2 nanoparticles to molten binary nitrate salt reduces the corrosion rate of carbon steel more than twice and stabilizes the corrosion scale at 390 °C. The anticorrosion effect of TiO2 nanoadditive was attributed to the formation of iron-titanium mixed oxide on the carbon steel surface. It was confirmed by XRD and TGA techniques that addition of TiO2 nanoparticles does not alter the stability of the salt. In view of presented results, the feasibility of molten salts based nanofluids in the CSPs can be reconsidered in terms of improved compatibility with construction materials.