Si3N4/TiC nanocomposite ceramics have been fabricated by hot pressing technique with AI2O3 and Y2O3 as additives.The results showed that well dispersed composite powder wascarried out by adding dispersant and adjusting pH valuesof suspensions. Remarkable increase in flexural strength at room temperatures was obtained by adding nanoparticlesin Si3N4 matrix with 10% (wt pct) of nano-Si3N4 and 15% of nano-TiC. The flexural strength, fracture toughnessand hardness were 1025 MPa, 7.5 MPa·m1/2 and 15.6 GPa, respectively. The microstructures of materials wereanalyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which indicated thatTiC nanoparticles distribute in the matrix and at the grain boundaries. According to the fracture form, low contentsof nano particles could refine matrix grains and lead to the track deflection as well as crack pinning. The multiplexmicrostructure was formed by mixing nano-Si3N4 particles. The crack trajectories exhibited crack deflection, rod-likegrain bridging and pull-out.
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