Carbothermic synthesis of monodispersed spherical Si3N4/SiC nanocomposite powder

The synthesis and structure of a monodispersed spherical Si3N4/SiC nanocomposite powder have been studied. The Si3N4/SiC nanocomposite powder was synthesized by heating under argon a spherical Si3N4/C powder. The spherical Si3N4/C powder was prepared by heating a spherical organosilica powder in a nitrogen atmosphere and was composed of a mixture of nanosized Si3N4 and free carbon particles. During the heat treatment at 1450 degrees C, the Si3N4/C powder became a Si3N4/SiC composite powder and finally a SiC powder after 8 h, while retaining its spherical shape. The composition of the Si3N4/SiC composite powder changed with the duration of the heat treatment. The results of TEM, SEM, and selected area electron diffraction shelved that the Si3N4/SiC composite powder was composed of homogeneously distributed nanosized Si3N4 and SiC particles.