Direct ink writing of IR-transparent yttria ceramics

• Transparent Y 2 O 3 ceramics was obtained by DIW and vacuum sintering at 1720°C. • The effect of solid loading and organic aids on the rheology of slurries was studied. • Optimal composition of printable aqueous inks was found. • In-line transmittance of 3DP Y 2 O 3 ceramics is ∼43% at 3–5 µm. In this work, transparent Y 2 O 3 ceramics were obtained by direct ink writing (DIW) followed by vacuum sintering at 1720°C for 32 h. The optimal ink composition was identified as 78 wt.% of solid loading, 1.5 wt.% of Dolapix CE64, 8 wt.% of Pluronic and 5 wt.% of ethylene glycol. The ink exhibits pseudoplastic behaviour and optimal viscoelastic properties for printing. Transparent Y 2 O 3 ceramics were characterized by mostly uniform dense microstructure with the presence of some large defects caused by the printing process. In-line transmittance of the obtained ceramics is 43 % in the range of 3–5 μm.