Interfacial reaction mechanisms of 3D SiO2f/Si3N4 composites prepared by perhydropolysilazane

Abstract

Three-dimensional quartz fiber-reinforced silicon nitride composites were prepared by perhydropolysilazane (PHPS) infiltration and pyrolysis method, and the microstructures and interfacial reaction mechanisms were investigated by Fourier transform infrared spectrometer, solid-state 29Si MAS NMR spectrometer, field emission scanning electron microscope, and high-resolution transmission electron microscope (HRTEM). Strong interfacial adhesion was observed for the composites due to the formation of silicon oxynitrides in the fiber/matrix interfaces. HRTEM images of the composites after thermal treatment at 1873 K showed α-cristobalite, α-Si3N4, and amorphous silicon oxynitrides, corresponding to crystallized quartz fibers, crystallized silicon nitride matrix, and noncrystalline interfacial phases. The interfacial reactions resulted from the silicon hydroxyl groups on the surfaces of quartz fibers and the active radicals in PHPS during infiltration and high-temperature pyrolysis.