Study of the mechanical properties, toughening and strengthening mechanisms of Si3N4/Si3N4w/TiN nanocomposite ceramic tool materials

Si3N4/Si3N4w/TiN nanocomposites were fabricated by a hot-pressing technology with different sintering processes. The effect of nanoscale TiN and Si3N4w on the mechanical properties was investigated. The microstructure and indention cracks were observed by scanning electron microscopy, transmission electron microscopy and energy-dispersive spectrometry investigations. The research results showed that Si3N4/Si3N4w20/TiN5 nanocomposites containing 5 vol.% of nanoscale TiN and 20 vol.% of nanoscale Si3N4w, which were sintered under a pressure of 30 MPa at a temperature of 1650 °C for 40 min, had optimum mechanical properties. The addition of both nanoscale TiN and nanoscale Si3N4w contributed to the microstructural evolution and an improvement of the mechanical properties. The toughening and strengthening mechanisms are discussed for Si3N4/Si3N4w20/TiN5 nanocomposites.