Effects of sol infiltration treatment on YSZ electrolyte coatings prepared by EB-PVD

To explore the effects of sol infiltration treatment on YSZ electrolyte coatings prepared by electron beam physical vapor deposition(EB-PVD), 8YSZ electrolyte coatings were prepared by EB-PVD at a deposition rate of 1 μm/min. Cross-sectional SEM analysis showed that the as-deposited coatings exhibited a loose columnar structure resulting in bad gas tightness. So a sol infiltration treatment was performed by immersing EB-PVD coatings in a zirconium and yttrium sol followed by a heat treatment. SEM analysis demonstrated that the sol could permeate the coatings with an impregnation depth of 3 μm. The intergranular pores and gaps of as-deposited coatings had been stuffed by decomposed products from sol. After infiltration treatment, the coefficient of gas permeability dropped from 6.78×10^-5 cm⁴/(N·s) for as-deposited coating to 6.54×10^-6 cm⁴/(N·s) for the coating after 8 times of infiltration treatment. However, the electrical conductivity of YSZ coating even after 8 times of sol infiltration treatment increased no more than 10% compared to that of as-deposited coating.