Influence of New Glass Phase Structure on the Mechanical Properties of Composite Ceramic SiC/Si3N4

Abstract

Though the addition of a second phase is an effective method for toughening silicon nitride (Si3N4) ceramics, certain residual thermal stress is generated at the phase interface. In case of a large value of residual thermal stress, a weak interface forms between the second phase and the matrix material, reducing the strength of the material. Herein, a new type of core–shell structure silicon carbide SiC–glass phase is produced inside the material by adding a presintering process into the traditional SiC–Si3N4 sintering process. The radial and tangential thermal stresses around the core–shell structural SiC–glass phase and SiC particle are compared by using the finite element method. The results indicate that the core–shell structural SiC–glass phase inhibits the interfacial debonding. Compared with the introduction of SiC particle alone, the core–shell structural SiC–glass phase optimizes the mechanical properties of SiC/Si3N4 composite ceramic, with the fracture toughness reduced by 9.6%, the bending strength increased by 12.3%, and the friction coefficient reduced by 8.5% for the SiC/Si3N4 ceramics with SiC content of 5%.