Microstructure and properties of silicon carbide whisker reinforced zirconium diboride ultra-high temperature ceramics

摘要

Hot-pressed zirconium diboride (ZrB_2) matrix composites containing 0-30 vol percent silicon carbide (SiC) whiskers have been investigated to determine the effect of composition (i.e. amount of SiC whiskers) on the microstructure, mechanical properties and thermal properties. With increasing SiC whisker volume contents, the flexural strength and fracture toughness of the composites were improved compared to those of monolithic ZrB_2. Flexural strength increased from 629 MPa for pure ZrB_2 to 767 MPa for ZrB_2-30 vol percent SiCw. Likewise, fracture toughness ranged from 5.4 to 7.1 MPam~(1/2) over the same composition range. Specific heat capacity increased with SiC whisker addition, while thermal diffusivity and thermal conductivity decreased slightly with the increase of SiC whisker content.