Bulk TiC xN 1-x-15%Co cermets obtained by direct spark plasma sintering of mechanochemical synthesized powders

Abstract

TiC xN 1-x-15 wt.%Co cermets were obtained by a mechanically induced self-sustaining reaction (MSR) and sintered by spark plasma sintering (SPS) technique at different temperatures (1200-1400°C) for 1 min in vacuum under a uniaxial load of 80 MPa. The evolution of microstructure and mechanical properties was investigated. SPS allowed high densification with limited grain growth at a relatively low temperature. Material sintered at 1300°C showed a good combination of mechanical properties with Vickers hardness of 17.1 ± 0.5 GPa, fracture toughness of 5.51 ± 0.29 MPa m 1/2 and bending strength of 904 ± 12 MPa. Lower sintering temperature resulted in a decrease in bending strength due to poor cohesion between the ceramic and binder phases. An increase in sintering temperature would allow tailoring the cermet microstructure and, therefore, adjusting the Vickers hardness/fracture toughness relation. Crown Copyright © 2012 Published by Elsevier Ltd. All rights reserved.