Kinetic evaluation of YSZ/Al2O3 nanocomposite coatings fabricated by electrophoretic deposition on a nickel-based superalloy

Abstract

In the current study, the evolution of deposition yields with time for yttria stabilized zirconia (YSZ)/Al2O3 nanocomposite coatings deposited by electrophoretic technique was described by a kinetic model. Aluminium powder was used as a sintering aid and also the source for the formation of Al2O3 during sintering. A mixture of ethanol and acetylacetone was utilized as the solvent. In order to prepare a stable suspension, surface charges and electrostatic interaction between particles in suspensions were evaluated through analyses of pH, zeta potential, and particles size. Electrophoretic deposition (EPD) on Inconel 718 electrodes was successfully carried out by employing three well-dispersed suspensions including nanostructured YSZ with 0, 30 and 50 wt.% of Al particles. The influences of three different applied voltages (25, 45 and 65 V), deposition time and the weight percent of Al particles on the EPD kinetic at a time interval of 0-300 s were studied and quantified based on the Baldisserri equation. It was shown that the results achieved from the Baldisserri model were almost well matched with the experimental data within a wide range of time. It was found that the deposition rate declines with the increase in YSZ nanoparticles content and time. The coated substrates in the final step were dried and sintered at 1150 ?C. The coating quality and surface morphology were characterized by field emission scanning electron microscopy (FE-SEM).