Objective To investigate the mechanical properties and microstructure of nano-zirconia toughened alumina ceramics with variety of nano-zirconia content in centrifugal infiltrate casting processing of dental all-ceramic. Methods Composite powder with different ethanol-water ratio, obtained serosity from ball milling and centrifugal infiltrate cast processing of green, then sintered at 1 450 ℃ for 8 h. The physical and mechanical properties of the sintered sample after milling and polishing were tested. Microstructures of the surface and fracture of the sintered sample were investigated by SEM. Results The experimental results showed that there had statistical significience （P＜0.01） on static three-point flexure strength and Vickers Hardness in three kinds of different nano-zirconia content sintered sample. Fracture toughness of 20% group was different from other two groups, while 10% group had not difference from 30% group（P＜0.05）. The mechanical properties of this ceramic with 20% nano-zirconia was the best of the three, the static three-point flexure strength was（433±19） MPa and fracture toughness was（7.50±0.56） MPa·m1/2. The intra/inter structure, fracture of intragranular and intergranular on the surface and fracture of sintered sample in microstrucre was also found. Conclusion Intra/inter structure has strengthen toughness in ceramics. It has better toughness with 20% nano-zirconia, is suitable dental all-ceramic restoratives.
