Preparation, microstructure and mechanical properties of ZrB_2-ZrO_2 ceramics

摘要

ZrB_2-ZrO_2 ceramics with ZrO_2 content varied from 15 to 30 vol.percent were prepared by hot pressing. The content of ZrO_2 was found to have an evident effect on the preparation, phase constitution, microstructure as well as the mechanical properties of ZrB_2-ZrO_2 ceramics. ZrB_2-30 vol.percent ZrO_2 provided the optimal combination of dense microstructure (2.6 |mum, as the average grain size) and excellent properties, including the flexural strength of 803 MPa, and the hardness of 22.7 GPa tested under 9.8 N. The highest t-ZrO_2 transformability of 35.2 vol.percent during fracture for ZrB_2-30 vol.percent ZrO_2 brought the best toughness of 6.5 MPa m~(1/2) compared with any other ceramic. In addition, the dependence of toughness on the test method as well as the hardness on the indentation load was also investigated.