β-SiAlON/TiN nanocomposites prepared from TiO2-coated Si3N4 powder

In this study the fabrication of β-SiAlON/TiN nanocomposites by sintering Si3N4 powder coated with nanosized titania or TiN particles was studied. The TiO2 coating on the Si3N4 powder was prepared by the sol–gel method from tetra-butyl titanate. Two approaches were used for the preparation of the β-SiAlON/TiN composites: the first was the reaction sintering of TiO2-coated Si3N4 powder, and the second was the calcination of the coated Si3N4 powder and subsequent sintering. The results show that during the thermal treatment and/or sintering of the coated Si3N4 powder the titania reacts with the Si3N4 to form TiN. However, during sintering the segregation and densification of small, nanometric TiN particles occurs. Despite the fact that the samples were prepared from relatively cheap starting materials and were sintered at atmospheric pressure they have high densities and relatively good bending strengths.