Preparation and Properties of Stable Suspensions of ZrO2–Y2O3 Powders with Different Particle Sizes for Electrophoretic Deposition

Abstract

This paper presents a study of nonaqueous suspensions based on ZrO2–8 mol % Y2O3 (8YSZ) powders and describes the use of the powders for producing thin-film coatings on a La2NiO4 (LNO) substrate by electrophoretic deposition (EPD). Stable suspensions for EPD have been prepared using 8YSZ powders differing in morphology and particle size: nanopowder (YSZ_L) produced by a laser evaporation–condensation process and commercially available powder (YSZ_T) (Tosoh, Japan). Ultrasonic processing has been found to have different effects on the particle size composition of the YSZ_L and YSZ_T suspensions. The two types of suspension have been shown to differ significantly in the kinetics of the deposition current at constant voltage: during deposition from the YSZ_L suspension, the current was observed to rise, whereas in the case of the YSZ_T suspension the current decreased markedly with deposition time. The YSZ_L film has been shown to be denser than the YSZ_T film. After sintering at 1350°C, it consisted of completely formed grains ranging in size from 1 to 5 μm. To remove surface pores in YSZ_T coatings, they should be sintered at a temperature of 1450°C.