Digital image correlation technique for full-field deformation of SOFC at 1300 ° C: An efficient speckle pattern for porous and diffusible substrates

Because of the pressing environmental issues, solid oxide fuel cells (SOFC) are being widely used. Being able to characterize the SOFC's high-temperature deformation is crucial for studying the high-temperature strength and durability. However, the electrode (i.e. NiO-YSZ anode) has a porous structure and is diffusible under high temperatures, causing challenging problems for the digital image correlation (DIC) experiments. In this study, we propose to prepare the speckle pattern using a sodium silicate-based method, enabling the DIC to quantify the deformation of the whole field at temperatures as high as 1300 degrees C. In addition to the speckling method, a hightemperature DIC experimental equipment was designed and setup with blue light illumination and filter, multiple illumination inlets and self-developed calibration board. Thermal strains under elevated temperatures were measured, and then the proposed approach was validated using the comparison of the computed thermal expansion coefficients. It turns out that the speckling method is simple yet efficient for the porous and diffusible substrate, and one can accurately measure the SOFC's full-field deformation by using the DIC approach.