Fabrication of TiN/Si 3 N 4 Ceramics by Spark Plasma Sintering of Si 3 N 4 Particles Coated with Nanosized TiN Prepared by Controlled Hydrolysis of Ti(O‐ i ‐C 3 H 7 ) 4

TiN‐coated Si 3 N 4 particles were prepared by depositing TiO 2 on the Si 3 N 4 surfaces from Ti(O‐ i ‐C 3 H 7 ) 4 solution, the TiO 2 being formed by controlled hydrolysis, then subsequently nitrided with NH 3 gas. A homogeneous TiO 2 coating was achieved by heating a Si 3 N 4 suspension containing 1.0 vol% H 2 O with the precursor at 40°C. Nitridation successfully produced Si 3 N 4 particles coated with 10–20 nm TiN particles. Spark plasma sintering of these TiN/Si 3 N 4 particles at 1600°C yielded composite ceramics with a relative density of 96% at 25 vol% TiN and an electrical resistivity of 10 −3 Ω·cm in compositions of 17.5 and 25 vol% TiN/Si 3 N 4 , making these ceramics suitable for electric discharge machining.