Evolution of the microstructure and mechanical properties of zirconia-based composites sintered by microwave technology

This work aims to produce zirconia-based materials by microwave sintering process for dental and prosthetic applications. Two compositions were evaluated: alumina-toughened-zirconia with 25 wt.%Al 2 O 3 , stabilized with 10.5 wt.%(Ce, Y), and yttria-stabilized-zirconia (5.4 wt.%Y 2 O 3 ). The microstructural evolution and its influence on their mechanical properties were analyzed. The composites were sintered by conventional sintering at 1400 and 1500°C with 2 h dwelling, and by microwave sintering at 1200 and 1300°C with 10- and 15-min dwell times, resulting in fully densified ceramics. Relative densities are > 97% and HV higher than 11 GPa for all compositions and sintering conditions. The FESEM images confirm the formation of platelets at higher temperatures, which results in an increase in fracture toughness from 5.0 to 8.2 MPa·m 1/2 . The low-thermal-degradation indicates that the composite performs well and that the tetragonal-to-monoclinic transformation is absent after 40h of ageing, making this material suitable for dental and prosthetic applications.