Effect of HCl concentration on the sintering behavior of 8 mol% Y2O3 stabilized ZrO2 deposits produced by electrophoretic deposition (EPD)

In this work, we have investigated the effect of HCl concentration and particle packing on the sintering behavior of 8 mol% yttria-stabilized-zirconia (8YSZ) deposits. 8YSZ deposits were fabricated by electrophoretic deposition (EPD). For 8YSZ coatings, it was found that the concentration of HCl in the EPD suspension significantly influences the neck size to grain size ratio. High neck size to grain size ratio (0.8 ± 0.03) was found in the sintered 0.8 HCl coating. The grain growth was observed to depend on the initial particle packing in the green coating. The effect of chloride ions on the grain and neck growth as well as elemental segregation within the 8YSZ is investigated using photoelectron spectroscopy (XPS) which confirmed the presence of chloride ions in green and sintered 8YSZ coatings. This was later confirmed using high-resolution transmission electron microscopy (HRTEM) and thermal analysis techniques. It was found that the presence of chloride ions induced an increase in the oxygen vacancy concentration at the grain boundaries. High oxygen vacancy concentration in the grain boundaries could promote neck growth of 8YSZ.