Effect of YSZ sol-gel coating on interaction of Crofer22 APU with sealing glass for solid oxide fuel/electrolysis cell

Interactions between the metal interconnect and glass sealant in the solid oxide cells stack are critical to retaining the system integrity. To address this issue, in the current study, 8YSZ coating is applied on the Crofer22 APU steel via sol-gel and dip-coating method. Dense and continuous 8YSZ coatings are obtained on Crofer22 APU substrates. X-ray diffraction and Raman spectroscopy results show that both cubic and tetragonal structures of 8YSZ are formed. A glass-based sealing paste is applied on bare and 8YSZ coated Crofer22 APU steel. The interfacial compatibility and chemical stability of steel/glass and steel/8YSZ/glass joint couples are investigated using SEM and EDS line scan analysis after the sealing process as well as 1000 h (10 thermal cycles) aging at 800 °C in air atmospheres. Very good compatibility is found between the coated steel and the glass. No significant interactions, cracks formation, or failure are observed at both steel/8YSZ and 8YSZ/glass interfaces, suggesting that the YSZ protective layer can effectively act as a barrier to interdiffusion of metal and glass elements. Finite element analysis shows that the generated residual stresses in the presence of the coating layer are not significant to be detrimental for the examined interfaces. [Display omitted] •The 8YSZ coating successfully applied on croffer22 APU substrate through the sol gel and dip coating method.•The coating stability and integrity are relatively preserved through the interface after 1000 h heat treatment in air.•The 8YSZ Coating prevents the undesirable diffusion of Cr and Fe into the GL glass.•Detrimental formation of SrCrO4 at the crofer/GL sealant interface successfully suppressed by 8YSZ Coating.•8YSZ coating eliminates the residual stress that cause mechanical failure.