Development of Self-Passivating, High-Strength Ferritic Alloys for Concentrating Solar Power (CSP) and Thermal Energy Storage (TES) Applications

Concentrating solar power (CSP) and thermal energy storage (TES) based on molten salts still lacks economic feasibility, with the material investment costs being a major drawback. Ferritic stainless steels are comparatively cheap class of materials that could significantly contribute to cost reductions. The addition aluminum ferritic steel can result in self-passivation by forming compact Al2O3 top layer, which exhibits higher corrosion resistance salt compared Cr2O3 surface layers typically formed expensive structural alloys for CSP TES, such as austenitic Ni-base super alloys. However, date, no combining formation sufficient strength is available. For this reason, cyclic tests under flowing synthetic air were carried out seven Laves phase-forming, model (17Cr2-14Al0.6-1Nb2.6-4W0.25Si), using “solar salt” (60 wt. % NaNO3 40 KNO3). Al content was varied investigate influence precipitation mechanically strengthening phase, well impact Al-oxide layer. W Nb contents increased examine their phase. experiments demonstrated simultaneous against attack mechanical fine phase particles possible novel HiperFerSCR (salt corrosion-resistant) steel. Microstructural examination unveiled compact, continuous layer 5 higher. Furthermore, stable distribution fine, precipitates achieved metal matrix, resulting combination potentially high solid solution strengthening. These results show high-strength suitable use applications.