Fabrication and characterization of SiO2（f）/Si)3N4 composites

A silicon dioxide fiber-reinforced silicon nitride matrix (SiO2/Si3N4) composite used for radomes was prepared by chemi- cal vapor infiltration (CVI) process using the SiCl4-NH3-H2 system. The effects of the process conditions, including infiltration tem- perature, infiltration time, and gas flux were investigated. The energy dispersion spectra (EDS) result showed that the main elements of this composite contained Si, N, and O. The X-ray diffraction (XRD) results indicated that phases of the composite before and after treatment at 1350°C were all amorphous. A little fiber pull-out was observed on the cross section of the composite by scan electron microscope (SEM). As a result, the composite exhibited good thermal stability, but an appropriate interface was necessary between the fiber and the matrix.