Preparation and properties of 2D fused-silica fiber reinforced porous Si₃N₄-SiO₂ matrix composites

2D fused-silica fiber reinforced porous Si₃N₄-SiO₂ matrix composites were prepared by combining the slurry method and vacuum infiltration technology. X-ray diffraction technique was used to analyze the crystallization behavior of the fused silica with different binders and of the addition of silicon nitride. The polished section and fracture morphology of the composites with different cycles of infiltration were characterized by SEM. Using crack deflection parameter, the fracture models were discussed. The results show that the concentration of Na⁺ has great effect on the crystallization of silica, while Si₃N₄ powder has little influence on it. Increasing the cycles of infiltration, the strength of the composites can not be improved, but the crack deflection parameter decreases, the fracture model converts toughness rupture into brittle rupture, and the fracture morphology turns out to be multistage pull-out rather than whole fiber tow pull-out.