Investigating the role of grain boundary hydrogen in dual atmosphere effects for solid oxide cells interconnect applications

Abstract

Ferritic stainless steel (FSS) is widely used as an interconnect material in solid oxide cells (SOCs). However, these interconnects degrade faster under simultaneous exposure to oxidizing and reducing atmospheres, a phenomenon known as the dual atmosphere effect. This study used SUS430 to investigate the mechanisms behind this effect. Oxidation behavior was compared for single air atmosphere, and dual atmosphere at 750 °C after 50, 100, and 200 h. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed significant hydrogen enrichment at grain boundaries after 200 h in the dual atmosphere exposure as compared to the single atmosphere. To explore hydrogen’s role, first-principles calculations were performed evaluating its adsorption energy on the (110) Fe-Cr crystal plane and its impact on Cr diffusion. The results revealed that hydrogen’s presence raises the energy barrier for Cr diffusion and alters its pathway. This suggests that hydrogen enrichment at grain boundaries is a major factor in the dual atmosphere effect, as it hinders Cr diffusion, contributing to accelerated degradation of interconnect materials.