Two-step hot pressing of bimodal micron/nano-ZrB2 ceramic with improved mechanical properties and thermal shock resistance

The densification and grain growth behaviors for micron- and nano-sized ZrB2 particles were investigated. The densification on-set temperature (Td-micron) and grain growth on-set temperature (Tg-micron) for micron-sized ZrB2 particles were about 1500 degrees C and 1800 degrees C, respectively. And the densification on-set temperature (Td-nano) and grain growth on-set temperature (Tg-nano) for nano-sized ZrB2 particles were about 1300 degrees C and 1500 degrees C, respectively. A bimodal micron/nano-ZrB2 ceramic was therefore prepared using a novel two-step hot pressing. A high relative density of 99.2%, an improved flexural strength of 580.2 +/- 35.8 MPa and an improved fracture toughness of 7.2 +/- 0.4 MPa.m(1/2) were obtained. The measured critical thermal shock temperature difference (Delta T-c) for this bimodal micron/nano-ZrB2 ceramic was as high as 433 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.