An innovative processing route for fabricating porous zirconia ceramics has been developed based on traditional injection molding method. Azodicarbonamide (AC) was used as the foaming agents and mixed with the zirconia powder and conventional binders (polypropylene, ethylene/vinyl acetate, paraffin wax and stearic acid). There were three stages in the foaming course: (1) Small bubbles nucleated when AC decomposed into N_2 and CO in the barrel. (2) Viscosity and pressure drop led to the growth of the bubbles when the melt feedstock was injected into the die cavity. (3) The porous structure was kept in the solidified body. The AC content and injection parameters were optimized to control the pore density and size. The porous green body was debinded at the heating-up rate of 0.5 °C /min to 450°C and sintered at 1550°C. Samples with porosity of 40%-50% and pore sizes from 200-250μm were prepared when the addition of AC was 0.3% by weight. The results showed that ceramic injection molding method was also suitable for fabricating the porous ceramics.
展开▼
