Direct ink writing of zirconia three-dimensional structures

Abstract

Tailoring the rheological properties of colloidal inks is critical for the direct ink writing of three-dimensional structures. The rheological properties of zirconia colloidal inks are extremely sensitive to the concentration of ammonium polyacrylate (NH₄PAA). The colloidal ink containing 47 vol% ZrO₂, 0.005 g ml⁻¹ cellulose and 0.8 wt% NH₄PAA dispersant showed a low viscosity of 3 Pa s at a characteristic shear rate of 50 s⁻¹ and maintained an equilibrium elastic modulus of 8 × 10⁴ Pa when the stress amplitude was up to 200 Pa. Three-dimensional structures with a feature size of 200 μm were successfully assembled with fine integrity.