A study on the electrophoretic deposition of 8YSZ coating using mixture of acetone and ethanol solvents

Electrophoretic deposition (EPD) was carried out on nickel metal sheets using acetone and ethanol mixtures. The ratios of the organic solvents in the suspension was varied to arrive at the optimum ratio of solvents and experimental conditions suitable for getting adherent and crack-free yttria-stabilized zirconia (YSZ) coatings. The volume ratios of acetone to ethanol used in the present study were 100:0 mL (4A:0E), 75:25 mL (3A:1E), 50:50 mL (2A:2E), 25:75 mL (1A:3E) and 0:100 mL (0A:4E). Iodine was used as an additive to charge the YSZ particles. The applied dc voltage was varied from 10 to 40 V cm−1 and also the deposition time was varied 4, 6 and 8 min. The effect of applied dc voltage during EPD on the weight of the deposit and in turn on the thickness of the coating obtained was studied. The YSZ deposits were viewed under a metallurgical microscope to determine the presence of cracks or other defects in the as deposited coatings after initial drying. Attempts were made to understand the observed behavior of different solvent ratios with the number of protons released. This study facilitated to arrive at the optimum solvent ratio (3A:1E and 2A:2E) and the experimental conditions required for getting smooth, homogeneous, crack-free YSZ coatings by EPD on nickel substrates. Using the optimized condition of 2A:2E, lanthanum-doped strontium manganite (LSM) tube which acts as cathode in tubular solid oxide fuel cells (SOFCs) was coated with 8YSZ using EPD. The electrophoretically coated YSZ coating on sintering showed a dense microstructure.