Characterisation of Solid Oxide Fuel Cell Ni–8YSZ substrate by synchrotron X-ray nano-tomography: from 3D reconstruction to microstructure quantification

A methodology, based on synchrotron X-ray nano-tomography measurements, is proposed to obtain 3D reconstructions of porous supports for Solid Oxide Fuel Cell (SOFC). The methodology has been applied to investigate the microstructure of a typical Ni–8YSZ cermet substrate of an Anode Supported Cell (ASC). Experimental conditions have been optimised so that a 3D reconstruction of 42 μm × 42 μm × 105 μm has been computed with a voxel size of 60 nm.The 3D reconstruction has been numerically analysed showing a quasi isotropy over the medium. A special attention has been paid to compute the morphological properties controlling the gas diffusion through the support. In this frame, it has been found that a volume as large as 35 μm × 35 μm × 35 μm is required to be statistically representative for the whole substrate. More particularly, the tortuosity factor τ   has been calculated on the basis of finite element simulations. The effect of the boundary conditions taken for these simulations has been investigated. In the direction perpendicular to the anode/electrolyte interface, the tortuosity factor has been determined to τz=2.8−0.2+0.3.

► Hard X-ray nano-tomography has been used to investigate the microstructure of Ni–8YSZ substrate. ► A large reconstruction of 42 μm × 42 μm × 105 μm has been obtained. ► Such volume has been analysed to compute the morphological properties of the material. ► A tortuosity factor has been determined for this typical highly porous SOFC support.