Relationship between the process parameters and the saturation point in electrophoretic deposition

We used the electrophoretic deposition (EPD) process to fabricate a composite with glass frit and investigated the EPD parameters to find the optimum deposition time by understanding the relationship between the process parameters of zeta potential (ZP), pH, deposition yield and saturation point in a slurry. A binder and a dispersing agent were mixed properly with glass frit (0.2–25 μm, d50 = 8.77 μm) in an ethyl alcohol medium for the preparation of the slurry. The pH and ZP were in an inverse relationship to each other due to the generation of H3O+ ions with the addition of the dispersing agent in the slurry. The acidic nature of the slurry resulted in a decrease of the pH and an increase of the ZP. Otherwise, the pH increased with the addition of the glass frit in the slurry because H3O+ ions were absorbed on the glass frit. Therefore, the OH− ions correspondingly increased. The saturation point of EPD was strongly correlated with the variation of the pH in the slurry; this is caused by a chemical reaction between the ethyl alcohol and the ions that make up the glass frit. An adjustment of the pH variation and the saturation point in the slurry can be established with respect to the optimum deposition time in the slurry.