DIRECT SYNTHESIS AND SINTERING OF SILICON-NITRIDE TITANIUM NITRIDE COMPOSITE

Electrical discharge machining is an attractive machining technique wh ich requires electrically conductive ceramic materials. Silicon nitrid e based composites with 35-40% of TiN possess electrical conductivity high enough to use this machining technique. The composite powder was prepared by combustion synthesis and densified by pressure sintering ( sintering aids 6 wt% of Y2O3 and 4 wt% of Al2O3). High fracture toughn ess, K-c > 10.5 MPa.m(1/2), is typical for the composite. It can be ex pected that this material can compete with pure silicon nitride in app lications requiring complex machining.