Effects of curing atmosphere pressure on properties of silica fibre reinforced silicon-boron nitride matrix composites derived from precursor infiltration and pyrolysis

摘要

The curing stage of the precursor infiltration and pyrolysis (PIP) process was analysed. Three-dimensional silica fibre reinforced silicon-boron nitride composites (3D SiO_2fitride) were prepared through four PIP cycles from a hybrid precursor. The effects of curing atmosphere pressure on the properties of the composites were investigated. With increasing curing pressure, the density of SiO_2fitride composites increases and the mechanical properties and ablation resistance are improved greatly. The composite cured under 8 MPa has a relatively high density (1˙83 g cm-3) and its flexural strength and elastic modulus reach 148˙2 MPa and 41˙5 GPa respectively. The high pressure curing process can be used to prepare denser composites and a high density can lead to excellent mechanical properties and ablation resistance.