beta-SiAlON/TiN nanocomposites prepared from TiO_2-coated Si_3N_4 powder

摘要

In this study the fabrication of beta-SiAlON/TiN nanocomposites by sintering Si_3N_4 powder coated with nanosized titania or TiN particles was studied. The TiO_2 coating on the Si_3N_4 powder was prepared by the sol-gel method from tetra-butyl titanate. Two approaches were used for the preparation of the beta-SiAlON/TiN composites: the first was the reaction sintering of TiO_2coated Si_3N_4 powder, and the second was the calcination of the coated Si_3N_4 powder and subsequent sintering. The results show that during the thermal treatment and/or sintering of the coated Si_3N_4 powder the titania reacts with the Si_3N_4 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.