Effect of Surface Treatments on Dispersibility and EPD Behavior of Fine SiC Powder in Aqueous Suspensions

Abstract

Surface treatments, such as calcination, acid solution leaching and alkali solution leaching, were used to improve the dispersibility and increase the electrophoretic deposition (EPD) weight for a fine SiC powder. Main impurities including hydrophobic free carbon, hydrocarbon and fluorine ion on the particle surface caused the low dispersibility and less deposition for the as-received powder in aqueous suspension. After calcination, the dispersibility and deposition weight were enhanced obviously. Acid leaching and alkali leaching were more effective to eliminate these impurities. The deposition weights of the two kinds of powders were about 4 times larger than that of the as-received powder. Slight oxidation on the particle surface after acid leaching led to the largest deposition weight for the acid leached powder. The reason for the improvement caused by different treatments was discussed according to the results of zeta potential, FTIR, XPS analyses and ion conductivity test.