The preparation and spark plasma sintering of silicon nitride-based materials coated with nano-sized TiN

TiN coating on β-sialon (z=2) and Si3N4 was performed by depositing TiO2 on their particle surfaces through controlled hydrolysis of Ti(O–i–C3H7)4, and subsequent nitridation with NH3 gas. TiN particles covering β-sialon and Si3N4 were 10–20 nm in size. Spark plasma sintering of TiN/β-sialon composite particles produced ceramics with TiN networks of 0.1–0.5 μm wide at 1500 °C, but with TiN grains of 0.1–2.0 mm sizes isolated in the sialon matrix at 1600 °C. SPSed TiN/sialon ceramics at 1500 °C had >95% density of the theoretical one, irrespective of the TiN amount. TiN/sialon ceramics (25 vol.%) showed a lower electrical resistivity (∼10−3 Ω cm) making these ceramics suitable for electric discharge machining.