Preparation and characterization of Si3N4/TiN nanocomposites ceramic tool materials

Si3N4/TiN nanocomposites ceramic tool materials were sintered under 30 MPa at 1650 °C for 40 min. The effects of nano-scale TiN on the mechanical properties and microstructure were investigated. The strengthening and toughening mechanisms of Si3N4/TiN nanocomposites were studied by observing the fracture surfaces, samples for TEM and cracks. The oxidation resistance of Si3N4/TiN nanocomposites was also discussed based on the observation of microstructure. The results showed that the elongated Si3N4 grains which were pulled out from the fracture surfaces were reduced with the increase of the addition of nano-scale TiN, and many intragranular TiN grains were observed in Si3N4/TiN nanocomposites. The greater crack deflection and microcrack provided the contributions to the strengthening and toughening mechanisms for Si3N4/1 vol%TiN nanocomposite. However, Si3N4/TiN nanocomposites were oxidized strongly at higher temperature.