Densification and characterization of hot-pressed ZrC-based composite doped with Nb and CNT

ZrC-based composite doped with 20 vol.% niobium (Nb) and 3 vol.% carbon nanotubes (CNT) was prepared by hot pressing. Due to the addition of Nb and CNT, the sinterability of ZrC was significantly improved, resulting in highly dense matrix (99.28%) at reduced sintering temperature (1600 degrees C). The flexural strength was 590 MPa at room temperature and 563 MPa at 800 degrees C, respectively. The fracture toughness was 7.23 MPa.m(1/2), which increased by 80% compared with the monolithic ZrC (4 MPa.m(1/2)). In addition, the work of fracture was calculated to be 267 J/m(2). Based on the microstructure characterizations, the improved fracture properties could be attributed to crack deflection, crack bridging and crack branching, which consumed more fracture energy during the fracture process. (C) 2016 Elsevier Ltd. All rights reserved.