Effect of dip coating parameters on microstructure and thickness of 8YSZ electrolyte coated on NiO-YSZ by sol-gel process for SOFCs applications

Abstract

8 mol % Yttria stabilized zirconia (8YSZ) coatings are widely used as electrolytes in solid oxide fuel cells (SOFCs). In this study, sol-gel process was used in order to in-situ synthesis of 8YSZ electrolyte layer on NiO-8YSZ substrate applying dip coating method. Solid content, viscosity and withdrawal speed were investigated as effective parameters that affect quality and thickness of coatings. Fourier transform infrared radiation (FTIR), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analyses were used to evaluate the microstructure of 8YSZ film. A dense and uniform coating was obtained with increasing solid content. Reduced viscosity also yielded a better uniformity and formed crack free coatings. Thickness of coatings was controlled by withdrawal speed. Results reveal that a dense and uniform coating was obtained with molar ratio of [Formula presented] = 10 using sol only 5min after preparation. Minimum thickness was measured 10 μm at withdrawal speed of 1 cm/min.