Effects of Low-Modulus BN Inclusions on Properties of Y-TZP Ceramic

We investigate the structure and properties of ceramic based on tetragonal zirconia (Y-TZP) containing low-modulus inclusions of hexagonal boron nitride ( h -BN). (Y-TZP)( h -BN) ceramic samples with low h -BN content exhibit increased fracture toughness ( K 1 C ). The highest fracture toughness was observed for (Y-TZP)(0.5 wt % h -BN) ceramic: K 1 C = 12 ± 0.53 MPa m 1/2 . The increase in failure viscosity caused by incorporation of low-modulus inclusions (i.e., h -BN) is due to two dissipative mechanisms: the martensite transformation of the ZrO 2 matrix and crack arrest at relatively weak interfaces between the matrix and low-modulus inclusions of h -BN. As the proportion of h -BN increases, the contribution of martensite transformation to the fracture toughness diminishes, a consequence of the grain size of tetragonal zirconia diminishing, which makes this phase stable.