Preparation and characterization of Si 3N 4/TiC nanocomposite ceramics

Abstract

By adding nano-sized Si 3N 4 and nano-sized TiC particles into the submicro-sized Si 3N 4 matrix, Si 3N 4/TiC nanocomposite ceramics were fabricated by means of hot pressing technique with Al 2O 3 and Y 2O 3 as sintering aids. The experimental results showed that optimal mechanical properties were achieved for the composite with the addition of 10 wt.% nano-sized Si 3N 4 particles and 15 wt.% nano-sized TiC particles, with the flexural strength, fracture toughness and Vicker's hardness being 1090 MPa, 7.5 MPa·m 1/2 and 17 GPa respectively. The microstructure and phase composition of the composites were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the rod-like β-Si 3N 4 grains were characterized by an obvious duplex distribution, with small β-Si 3N 4 grains embedded in the matrix of large β-Si 3N 4 grains. The fracture surface of the composite was observed to exhibit a mix of intergranular and transgranular fracture as a probable result of the presence of both intergranular and intragranular TiC nanoparticles.