Preparation and properties of TiN–Si3N4 composites

TiN–Si3N4 nanocomposite powders were prepared by in situ direct nitridation of TiO2–Si3N4 nanocomposite powders prepared by a heterogeneous precipitation method using tetra-butyl titanate and silicon nitride as raw materials. TiN–Si3N4 dense composites were obtained by hot-pressing at 1550–1800 °C and 30 MPa for 1 h. The morphology of TiN–Si3N4 nanocomposite powder was observed by transmission electron microscopy, which showed that the average size of TiN nano particles was about 40 nm, and the surfaces of Si3N4 particles were uniformly coated with TiN nano particles. The effects of nano TiN particles on the mechanical properties and electrical conductivity of TiN–Si3N4 composites were studied. The addition of 20 vol.% TiN could increase the bending strength of the composite to 1154 MPa. The resistivity of composites decreased with the increase in TiN content and reached a minimum of 0.11Ω cm with 25 vol.% addition of TiN.