High-strength TiB2-TaC ceramic composites prepared using reactive spark plasma consolidation

This study demonstrates that reactive consolidation achieved via spark plasma sintering (SPS) is an effective strategy to enhance the high-temperature flexural strength of TiB2-based ceramics. Monolithic ceramics of TaC and TiB2 were consolidated by non-reactive SPS and were used as reference samples. The microstructural development during room- and high-temperature strength tests was analyzed. The room-temperature strength of TiB2 ceramics was analyzed as a function of the grain size. The high-temperature strength and associated microstructural development of monolithic TaC ceramics are reported for the first time. The TiB2 TaC ceramic system was then consolidated by reactive SPS at 2000 degrees C. The flexural strength of the 10 wt% TaC TiB2 ceramic composites reached 533 MPa at room temperature and 480 MPa at 1600 degrees C. The development of the (Ti,Ta)(C,B) phase was considered the main reason for the preservation of the high strength up to 1600 degrees C. Both bulk TaC and TiB2 exhibited drastic decreases in their bending strengths at 1600 degrees C because of the activation of plastic deformation associated with high-temperature creep, and their strength did not exceed 210 MPa. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.