Microstructure and properties of Al2O3(n)/ZrO2 dental ceramics prepared by two-step microwave sintering

Abstract The 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) ceramic and zirconia matrix ceramics doped with 7.5% (volume percent) nano-Al 2 O 3 (7.5Al 2 O 3 –92.5ZrO 2 ) were fabricated by two-step microwave sintering (MS-II), and two-step conventional sintering (CS-II) and one step microwave sintering (MS-I) as control group. The results show that the machinable index of two groups of samples varied considerably. The optimum first step sintering temperature of 7.5Al 2 O 3 –92.5ZrO 2 composite ceramics and 3Y-TZP ceramics were 950 °C and 900 °C, respectively. The properties of 7.5Al 2 O 3 –92.5ZrO 2 composite ceramics prepared by two-step microwave sintering were superior to that of two-step conventional sintering and one-step microwave sintering. The relative density of 7.5Al 2 O 3 –92.5ZrO 2 composite ceramics reached 99.35% by two-step microwave sintering. Its hardness, fracture toughness and bending strength were 13.09 GPa, 11.62 MPa m 1/2 and 766.89 MPa, respectively. Adding nano-Al 2 O 3 could improve microstructure of the ceramics and have an effect of dispersion strengthening, which enhanced the properties of the materials. Compared with the 3Y-TZP ceramics, the properties of ZrO 2 composites with alumina addition were greatly improved, the fracture toughness and the bending strength were improved 20.3% and 33.9%, respectively.

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