Preparation of Si_3N_4/SiO_2 Composites with Pressureless Sintering

Si3N4/SiO2 composites were prepared with pressureless sintering. It was found that the Si3N4 particle was effective to suppress the crystallization of cristobalite in the Si3N4/SiO2 composites and contributed to the improvement of the mechanical properties. After sintered at 1370℃for 2h, the flexural strength of the composites with 5vol% Si3N4 addition reached 96.2MPa, the fracture toughness was 2.4MPa·m1/2. The dielectric constant and loss tangent of the composites was 3.63~3.68 and 1.29-1.75×10-3, respectively.