Effect of mixing methods on superfine-zirconia ceramics by gel-casting

The dispersion effects of stirring, barreling and planetary milled were compared, the influences of planetary milled on rheological behaviors of superfine-zirconia (D₅₀=0.19 μm) slurries and the properties of green bodies and ceramics were studied; the reason in viscosity of overmilled slurries increasing were analyzed. The results show that the viscosity of slurries prepared by planetary milled is lower than others, the initial viscosity of 50 vol% slurries is only 0.289 Pa·s at 200 r/min for 4 h. For the overmilled slurries, the viscosity increasing is attributed to the decrease in particle size of ZrO₂ powder, and the viscosity can be significantly decreased by adding a little dispersant. The properties of green bodies and ceramics can be improved by increasing the milling time. The mean bending strength of ceramics is 960 MPa and the fracture toughness can be reach 17.3 MPa·m^1/2 when the milling time is 12 h.