Fabrication and mechanical properties of fibrous silicon nitride monolithic ceramics

Abstract

Fibrous Si3N4 monolithic ceramics with a hexagonal cell (Si3N4 fiber) and diameters in the range of 0.1-0.5 mm were processed using a composite fabrication method with a high preferred orientation by the tape casting of seeds of rodlike β-Si3N4 single crystals. The densified Si3N4 fibrous monolith showed a fracture toughness of 17 MPa·m1/2 and a three-point bend strength of 690 MPa. The application of reinforcement with SiC whiskers exhibited a fracture toughness (24 MPa·m1/2) and strength (705 MPa). Grain orientation, interface, and reinforcement played a deciding role in mechanical properties of these monolithic ceramics.