Effects of sintering velocity on the microstructure and mechanical properties of hot-pressed ZrB2–SiC–ZrO2f ceramics

The effects of cooling and heating velocity on the microstructure and mechanical properties of the hot-pressed ZrB2–20 vol.% SiC ceramics added with 15 vol.% Zirconia fiber were investigated in details. It was indicated that the appropriate cooling velocity could reduce the residual stress concentration, and the proper heating velocity could allowed the green compacts to get densified, which was favorable to enhance the flexural strength and fracture toughness to 1117 ± 98 MPa and 7.1 ± 0.5 MPa m1/2, respectively. Due to the introduction of the Zirconia fiber, the observed toughening mechanisms were attributed to the fiber debonding, fiber pull-out and phase transformation toughening. The results presented here point out a promising way for improving the mechanical properties of ZrB2-based ultra-high temperature ceramics.