pH localization: a case study during electrophoretic deposition of ternary MAX phase carbide-Ti3SiC2

Abstract

The pH localization phenomenon during electrophoretic deposition (EPD) of the MAX phase-Titanium silicon carbide (Ti3SiC2), from suspension in aqueous and mixed (water-ethanol) solvent was experimentally verified in presence of a cationic dispersant, polyethyleneimine (PEI). The local pHs at the electrodes were dependent on solid loadings of the suspensions; pH localization was pronounced at lower solid loading. Higher solid loading resulted in thicker deposits, shielding the electrode surface and hindering direct interaction of the electrode with the particles, thereby suppressing the change in local pH. Comparison of local pH at cathode during EPD from aqueous and mixed solvent revealed a delay in the attainment of isoelectric point (IEP) at the vicinity of electrode and slower deposition rate for mixed solvent. A necessity of concurrence between the IEP of the material and the local pH at the deposition electrode for a given system was established for the formation of good deposits. (C) 2013 The Ceramic Society of Japan. All rights reserved.