A Time Resolved Study of Precoated AISI 441 for SOFC Interconnects Using STEM-EELS - Part I

Tuesday, 28 July 2015: 16:40
Alsh (Scottish Exhibition and Conference Centre)
L. S. Karlsson, M. W. Lundberg, R. Berger, and J. Westlinder (AB Sandvik Materials Technology)
Precoated AISI441 for SOFC interconnectors were investigated by STEM-EELS looking at the diffusion processes in the initial stage of the oxidation. The PVD coating contained Ce and Co/Mn-alloy in two layers with at total thickness of 800nm. The samples were exposed up to 1000 hours at 800°C then characterized by TEM. Multiple linear least squares (MLLS) fitting of reference spectra aids the interpretation of the elemental maps due to overlapping edges (Figure 1). Within 4 min heat treatment the oxidation front has reached the substrate steel and Cr2O3 is forming at the stainless steel interface. CeO2 acts as the barrier line for Cr and is situated between the Cr-containing spinels and the (Co,Mn)-spinel after 72 h heat treatment.