Stabilization of Yttria Aqueous Suspension with Polyethylenimine and Electrophoretic Deposition

Stability of aqueous suspensions of yttria nano-sized particles prepared with Polyethylenimine (PEI) of three different molecular weights (Mw), 1800, 10000 and 70000, was investigated. Stability of the suspensions as a function of time was estimated by a viscosity measurement and infrared absorption spectroscopy (FT-IR). The highest stability was observed for the suspension prepared with PEI of Mw 10000. Isoelectric point of yttria was increased from 8.4 to 10.0 by PEI adsorption. PEI effectively works on the yttria particles not only to give positive surface charge but also to suppress hydration in aqueous solvent. Positively-charged yttria particles by PEI modification were deposited on a cathode by electrophoretic deposition and dense thick layer was successfully obtained.