Corrosion resistance of Hastelloys in molten metal-chloride heat-transfer fluids for concentrating solar power applications

Corrosion rates have been estimated for commercial Hastelloys C-276, C-22 and N types in eutectic molten salts containing NaCl, KCl and ZnCl2 using steady-state potentiodynamic method (0.2mVs−1 within ∼±30mV from the open circuit voltage). Hastelloy C-276 exhibited the lowest corrosion rates of ∼10 and 40μm per year in 13.4NaCl–33.7KCl–52.9ZnCl2 (mol%) salt at 250 and 500°C, respectively. The potentiodynamic method was validated by conducting traditional immersion test for corrosion rate estimation on C-276 Hastelloy in 13.4NaCl–33.7KCl–52.9ZnCl2 (mol%) at 500°C (corrosion rate ∼50μm per year). Among the samples evaluated, Hastelloy N showed highest corrosion rate of >150μm per year at 500°C. •This study deals with corrosion of Hastelloys in NaCl–KCl–ZnCl2 eutectic salts.•Electrochemical potentiodynamic method gives repeatable measurements.•Hastelloy types C-276 and C-22 show extremely low corrosion rate.