Characterization of SiC and Si3N4 nanoparticles and their aqueous dispersions

Nanoparticles of SiC and Si₃N₄ were previously used to obtain electroless NiP/particles nanocomposites. The incorporation process was very different, depending on the particle: SiC tended to agglomerate and had a high incorporation level; Si₃N₄ particles were not aggregated, but their incorporation level was very low. To try to explain these differences, the particles and their aqueous dispersions were characterized. Although the as-received products were both oxidized and of the identical mean size, results showed that the size distributions and the surface oxidation products were rather different. The zeta potential in water dispersions was similar and negative for both particles but, as the electrolyte ions were introduced, it showed a different evolution: nitride particles retained a small negative charge and carbide was almost uncharged. The overall results obtained in this study explain the different behavior of both ceramic particles and provide possible solutions to improve their co-deposition with nickel.