Dispersion of alumina and silicon carbide powders in alumina sol

Dispersion of Al2O3 and SIC particles in an alumina sol has been investigat ed through determination of particle-size distribution, zeta potential, and agglomerate morphology, The particle size of Al2O3 and SiC (as determined by the particle-size analyzer) Is strongly affected by the presence of alum ina sol in the solution, The average agglomerate size is decreased by at le ast 50%, The zeta potential of Al2O3 in 1M alumina sol increases slightly, whereas that of SiC reverses its sign over a wide range of pH values. It is proposed that these effects are caused by AlO4Al12(OH)(24)(H2O)(12)(7+) so l clusters (1-2 nm In size) that are absorbed on the surface of the large ( 1-5 mu m) ceramic particles, The electrostatic and steric effects of the cl uster absorption help to control the dispersion and stabilize the suspensio n of ceramic particles in the alumina sol during wet processing, It is expe cted that the alumina-sol clusters can be used as an efficient, clean dispe rsant for single-phase and composite ceramic powders.