Study of the mechanical properties, toughening and strengthening mechanisms of Si 3N 4/Si 3N 4w/TiN nanocomposite ceramic tool materials

Abstract

Si 3N 4/Si 3N 4w/TiN nanocomposites were fabricated by a hot-pressing technology with different sintering processes. The effect of nanoscale TiN and Si 3N 4w 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 Si 3N 4/Si 3N 4w20/TiN5 nanocomposites containing 5 vol.% of nanoscale TiN and 20 vol.% of nanoscale Si 3N 4w, 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 Si 3N 4w contributed to the microstructural evolution and an improvement of the mechanical properties. The toughening and strengthening mechanisms are discussed for Si 3N 4/Si 3N 4w20/TiN5 nanocomposites.