STABILIZATION OF ETHANOL BASED CERAMIC SUSPENSIONS FOR ELECTROPHORETIC DEPOSITION

Electrophoretic deposition (EPD) is a promising technique for fabrication of supported and unsupported films directly from stabilized suspensions. Al(2)O(3) suspensions in ethanol were prepared using citric acid as a dispersant. At an operational pH of 3, citric acid addition resulted in negatively charged Al(2)O(3) particle surfaces. Addition of citric acid before Milling Of Al(2)O(3) suspension resulted in finer particles and higher magnitude of zeta compared to citric acid addition after milling of Al(2)O(3) suspensions. Resulting suspension properties depended also on the citric acid concentration, which could be explained using the Detjaguin-Landau-Verwey-Overbeek (DLVO) theory. Citric acid concentrations between 0.4-0.68 wt% produced stable suspensions with Newtonian behavior, high surface charge, and low viscosities, down to 10 mPa.s for suspensions with 20 vol% solid loading. Citric acid was found to be an excellent dispersant for Al(2)O(3) in ethanol. Solid loading was found to be the most influential variable controlling the deposition rate during EPD, followed by voltage applied, deposition time and the distance between the electrodes.