A Novel Method to Improve the Dispersibility of Silicon Nitride Powders in Aqueous Media

The present study describes a novel method to improve the dispersibility of silicon nitride powders in aqueous media. Specifically, a new Si 3 N 4 @g-C 3 N 4 core–shell composite material was synthesized via annealing the mixture of silicon nitride and melamine under a nitrogen atmosphere using heating method. The effects of various initial mass ratios of Si 3 N 4 and melamine on the structure and dispersibility of the composite were systematically investigated. The results of X-ray photoelectron spectroscopy and transmission electron microscope demonstrated that as-obtained Si 3 N 4 @g-C 3 N 4 composite powders possess the core–shell structure, whereas the zeta potential and sedimentation analysis showed that they exhibit good dispersion in aqueous media. Furthermore, the colloidal dispersion of the composite powders is most stable when the initial mass ratio of Si 3 N 4 and melamine is 100:3. The coated g-C 3 N 4 could be completely removed in a cryogenic nitrogen atmosphere. The proposed process is expected to provide novel avenues for the study of dispersion of other inorganic powders.