Influence of sintering temperature on microstructure and properties of SiO2 ceramic incorporated with boron nitride nanotubes

Silica (SiO2) ceramic containing 5 wt% boron nitride nanotubes (BNNTs) was fabricated by hot pressing at 1200–1450 °C. The influences of the sintering temperature on phase composition, relative density, microstructure and mechanical and dielectric properties were investigated, respectively. As the increase of sintering temperature, mechanical properties varied dramatically, while the relative density and dielectric constant increased during the range of sintering temperature. The composite sintered at 1400 °C exhibited superior properties, attaining flexure strength of 120.5 MPa, fracture toughness of 1.21 MPa m1/2, dielectric constant of 4 and relative density of 92%. Particularly, flexure strength and fracture toughness were about 230.8% and 208.6% higher than those of monolithic SiO2, respectively.