Effect of particle size distribution on properties of zirconia ceramics prepared by direct ink writing

Abstract The effect of particle size distribution (PSD) on the rheological properties of zirconia slurries for Direct Ink Writing (DIW) and the physical-mechanical properties of the resulting sintered ceramics were systematically investigated in this paper. A series of aqueous ceramic slurries were prepared using sub-micron (average particle size 300 nm) and nano-sized (average particle size 50 nm) zirconia powders at a fixed solid loading of 58 vol% by adjusting their mass ratio. The optimal PSD was predicted based on the Dinger-Funk particle packing model. Specimens were fabricated using DIW and subsequently sintered at 1550 °C. The results demonstrated that the PSD significantly influenced the rheological behavior of the slurries. At a 5 wt% mass fraction of nano-zirconia, the slurry viscosity reached a minimum, exhibiting optimal printability. This optimal PSD also resulted in a peak relative density (99.1%) and the highest flexural strength (692 MPa) in the sintered specimens. Although the fracture toughness followed a different trend, monotonically increasing with the nanoparticle content to reach 9.7 MPa·m ^1/2 at 10 wt% nano-zirconia. The results indicate that adjusting the powder particle size distribution is a promising strategy for the fabrication of high-performance ceramic components via direct ink writing.