Effect of ZrB2 content on the densification, microstructure, and mechanical properties of ZrC-SiC ceramics

摘要

ZrC ceramics containing 30 vol% SiC-ZrB2 were produced by high-energy ball milling and reactive hot pressing. The effects of ZrB2 content on the densification, microstructure, and mechanical properties of ceramics were investigated. Fully dense ceramics were achieved as ZrB2 content increased to 10 and 15 vol%. The addition of ZrB2 suppressed grain growth and promoted dispersion of the SiC particles, resulting in fine and homogeneous microstructures. Vickers hardness increased from 23.0 +/- 0.5 GPa to 23.9 +/- 0.5 GPa and Young's modulus increased from 430 +/- 3 GPa to 455 +/- 3 GPa as ZrB2 content increased from 0 to 15 vol%. The increases were attributed to a combination of the higher relative density of ceramics with higher ZrB2 content and the higher Young's modulus and hardness of ZrB2 compared to ZrC. Indentation fracture toughness increased from 2.6 +/- 0.2 MPa-m(1/2) to 3.3 +/- 0.1 MPa.m(1/2) as ZrB2 content increased from 0 to 15 vol% due to the increase in crack deflection by the uniformly dispersed SiC particles. Compared to binary ZrC-SiC ceramics, ternary ZrC-SiC-ZrB2 ceramics with finer microstructure and higher relative densities were achieved by the addition of ZrB2 particles.