Fabrication of high performance 3D SiO2/Si3N4 composite via perhydropolysilazane infiltration and py

Perhydropolysilazane, a low viscosity preceramic polymer with good wettability and high char yield, was used to fabricate three-dimensional silica fiber reinforced silicon nitride matrix composites through the repeated infiltration-curing- pyrolysis cycles. With the increase of the pyrolysis temperature from T1, T2 to T3, the density of the composites increased all through, but the flexural strength showed a maximum value at T2 followed by a sharp decrease. The composite prepared at T2 exhibited a good ceramization of the preceramic polymer, a high flexural strength of 144.9 MPa and excellent dielectric property. The high performance of the composite resulted from the good state of the silica fibers, controlled fiber/matrix interfacial microstructures and high-purity dense silicon nitride matrix.