In Situ Polysilane‐Derived Silicon Carbide Particulates Dispersed in Silicon Nitride Composite

Abstract

A dense (97% of theoretical density) Si3N4—SiC composite containing 10 wt%β‐SiC was prepared by introducing a SiC phase by the pyrolysis of a polymeric SiC precursor. The composite material was produced by mixing an alkyl/aryl‐substituted polysilane with Si3N4 powder and, by subsequently forming green compacts, pyrolyzing the polymeric species, and finally sintering the sample. Synthesis and characterization of the polymeric compound was described. Its transformation reactions to SiC and the characterization of the ceramic residue were also studied. High ceramic yields were obtained by curing the as‐synthesized polysilane at 500°C in an Ar atmosphere. The heat treatment had no effect on the good solubility of the polymeric precursor in organic solvents. This was important for processes such as infiltration, sealing, and coating and for the mixing of the polymer with powders for the preparation of homogeneous composite ceramics. The dense microstructure of the pyrolyzed and sintered Si3N4 powder–polysilane mixture exhibited reduced grain growth of the Si3N4 particles and a very homogeneous distribution of the in situ‐formed β‐SiC phase.