Development of ZrO2 –ZrB2 composites
B. Basu, J. Vleugels, O. Van Der Biest
Yttria-stabilised tetragonal zirconia (Y-TZP) composites with 30 vol.% ZrB2 are prepared by hot pressing in vacuum for 1 h at 1450°C. Different commercial zirconia starting powders as well as a range of ZrO2 ‘powder mixture’ grades, based on co-precipitated powders were used for the composite production. The measured differences in the mechanical properties of the obtained composites is explained in terms of the microstructure, the residual stresses due to the presence of ZrB2 , and the stabiliser content and its distribution. While the stabiliser content and distribution remained significant, the residual stress in the zirconia matrix is found to be an important additional factor influencing the tetragonal zirconia transformability. Crack deflection by the ZrB2 phase was identified as an active toughening mechanism in the composites.