Mechanical Properties and Toughening Mechanisms of Si_3N_4 Matrix Laminated Ceramic Composite

摘要

Preparation technology, mechanical properties and microstructure of SiC whisker reinforced Si_3N_4 laminated ceramic composite sintered with La_2O_3 and Y_2O_3 additives were investigated in this paper. Gelcasting and hot-pressure sintering technologies were used to obtain the laminated SiC_w/Si_3N_4 composite. Flexure strength and fracture toughness of the testing material are 517MPa and 16.8MPam~(1/2) at room temperature, and 295MPa and 9.1MPam~(1/2) at 1350 ℃ respectively. Analysis of the fracture morphology and microstructure of the composite indicated that step fracture, interfacial cracking and microcrack in laminate are the main reason for improving the mechanical properties. At high temperature, BAS glass phase produced by components causes the mechanical properties of the testing material decrease obviously.