Enhanced toughness and reliability of Si3N4-SiCw composites under oscillatory pressure sintering

We reported an oscillatory pressure sintering (OPS) process to consolidate Si3N4-SiCw composites. For comparison, the composites were also prepared by hot pressing (HP) method. The specimen by OPS process reveals an accelerated rate of grain growth in the c axial direction and thus an increased average aspect ratio compared with the specimen by HP process. The oscillatory pressure also performs a positive impact on the Si3N4-SiCw composites as the bulk density of the OPS specimen increases to 3.270 g cm−3 accompanied with higher fracture strength and hardness of 1133 MPa and 16.1 GPa, respectively, compared with those of the HP specimen. Significantly, the increased fracture toughness and Weibull modulus found in the OPS specimen indicate toughening effects and material reliability are improved aided by the oscillatory pressure. Current results suggest OPS to be a promising technique for preparing highly densified Si3N4-SiCw composites with enhanced mechanical properties.