Fabrication and mechanical properties of TiB2/ZrO2 functionally graded ceramics

• Fabrication of novel TiB2/ZrO2 functionally graded ceramics
• The toughness of TiB2/ZrO2 functionally graded ceramics was essentially improved.
• It is a potential method for improving the toughness of TiB2/ZrO2 ceramics.

Five layers were considered for the present TiB2/ZrO2 functionally graded ceramics and TiB2/ZrO2 functionally graded ceramics were prepared by hot-pressing. The first layer, marked as L1, was composed of TiB2–15vol%SiC. The L2 layer was composed of TiB2–15vol%SiC–10vol%ZrO2. The L3 layer was composed of TiB2–25vol%ZrO2 without addition of SiC, because 25vol%ZrO2 was enough to densify TiB2. The last two layers, L4 and L5, were composed of TiB2–35vol%ZrO2 and TiB2–45vol%ZrO2, respectively. Denser graded microstructures as well as the stronger interfaces were achieved for TiB2/ZrO2 functionally graded ceramics hot-pressed at 1900 °C. Due to the phase transformation of ZrO2, the toughness of TiB2/ZrO2 functionally graded ceramics increased from ~ 4.3 MPa m1/2 for the TiB2-rich layer to ~ 8.9 MPa m1/2 for the ZrO2-rich layer. The effect of hot-pressing temperature on the toughness of TiB2/ZrO2 functionally graded ceramics was further investigated in detail.