Fabrication and characterization of 3Y-ZrO2/Al2O3 ceramic based on the raw materials dispersed by three-roller mixing

The homogeneous dispersion of the raw materials is the key process to prepare 3Y-ZrO2/Al2O3 ceramics. In engineering, the three-roller mixing is suitable for dispersing the high viscosity slurries containing the fine ceramic powders, which benefited reducing the amount of dispersion medium and drying time. The commercial 3Y-ZrO2 powder (80 nm) and two kinds of Al2O3 powders (3 mu m and 0.3 mu m) were used as the starting materials. 3Y-ZrO2/Al2O3 composite ceramics were prepared by three-roller mixing, die pressing, and sintering. The relation of phase compositions, microstructures, and bending strengths of the ceramics was investigated by XRD, SEM, and universal testing machine. The results show that the microscopic aggregation area of Al2O3 grains with the maximum size of 5-10 mu m exists in the 3Y-ZrO2/Al2O3 composite ceramics in addition to the normal dispersed phase of Al2O3 and the continuous phase of 3Y-ZrO2. The transition from the tetragonal to the monoclinic phase of 3Y-ZrO2 occurs with the addition of coarse Al2O3 powders. However, the tetragonal phase shifts to the right with no monoclinic phase detected in the samples with fine Al2O3 powders. The proper addition of the two Al2O3 powders is beneficial to achieving the maximum bending strength when the 3Y-ZrO2/Al2O3 ceramics are sintered at 1600 degrees C. However, the curve change of the bending strength of the composite ceramics with fine Al2O3 powder is smoother than that of the samples with coarse Al2O3 powder with the increase of Al2O3 volume fraction.