Effect of High Temperature CO 2 on Haynes 230 Alloy (Updated Jan 2021)
The supercritical carbon dioxide (sCO 2 ) Brayton cycle is a promising candidate for future nuclear reactors due to its ability to improve power cycle energy conversion efficiency. The sCO 2 Brayton cycle can operate with an efficiency of 45-50% at operating temperatures of 550-700 C. One of the greatest hurdles currently faced by sCO 2 Brayton cycles is the corrosivity of sCO 2 and the lack of long-term alloy corrosion and mechanical performance data, as these will be key to enhancing the longevity of the system, and thus the levelized cost of electricity. Past studies have shown that sCO 2 corrosion occurs through the formation of metal carbonates, oxide layers, and carburization, and alloys with Cr, Mo and Ni generally exhibit less corrosion. While stainless steels may offer sufficient corrosion resistance at the lower range of temperatures seen by the sCO 2 Brayton cycles, more expensive nickel-based alloys are typically needed for the higher temperature regions. This study investigates the effects of corrosion on the Haynes 230 alloy, with a preliminary view on changes in the mechanical properties. High temperature CO 2 is used for this study as the corrosion products are similar to that of supercritical CO 2 , allowing for an estimation of the susceptibility towards corrosion without the need for high pressure experimentation.