Synthesis and sintering properties of silica-coated titanium nitride particles

Abstract

Herein, we synthesized silica-coated titanium nitride (TiN/SiO2) particles via a sol–gel method and evaluated the hardness of the sintered bodies fabricated using the as-fabricated TiN/SiO2 particles. Commercially available micron-sized TiN particles were dispersed in a water–ethanol solution at 35 °C and then coated with SiO2 using a sol–gel method, tetraethyl orthosilicate (TEOS), and base catalysts. TiN/SiO2 particles with small specific surface areas owing to the presence of few micropores in their structure were obtained using NaOH as the base catalyst. The Vickers hardnesses of TiN, a mixture of TiN and SiO2 (TiN–SiO2), TiN/SiO2 fabricated using an ammonia solution as the base catalyst (TiN/SiO2A), and TiN/SiO2 fabricated using NaOH as the base catalyst (TiN/SiO2S) increased as follows: TiN (6.35 × 102 Hv) < TiN–SiO2 (1.01 × 103 Hv) < TiN/SiO2A (1.11 × 103 Hv) < TiN/SiO2S (1.15 × 103 Hv). In summary, the SiO2 shell served as a sintering aid, and the NaOH catalyst densified the sintered body and improved its hardness.