Re-establishing the paradigm for evaluating halide salt compatibility to study commercial chloride salts at 600°C-800°C

Chloride salts are one candidate for a >700 degrees C concentrating solar power (CSP) cycle, however, many reports from the literature suggest very high reaction rates between chloride salts and structural alloys. Historically, a specific methodology was established for evaluating halide salt compatibility based on solution kinetics. This study returned to that paradigm where the salts are purified and evaluated in sealed capsules before moving to a flowing experiment to determine a true corrosion rate in a temperature gradient for a commercial K-Mg-Na chloride salt. Isothermal testing focused on Ni-based alloys 230 and 600 at 600 degrees C-800 degrees C. The results indicated there were promising combinations of salt chemistry, temperature, and alloy composition that reduce the extent of reaction. The results of the first monometallic thermal convection loop of alloy 600 run for 1,000 hr with a peak temperature of 700 degrees C showed low attack with rates <= 9 mu m/yr.