Binder-mediated nano-CaTiO3 delivery for localized sintering activation and pore-network regulation of porous Y2O3 ceramics fabricated by binder jetting

Porous Y 2 O 3 ceramics are considered promising materials for applications such as titanium-alloy precision casting due to their high chemical compatibility with reactive Ti melts. Conventional binder-jetted Y 2 O 3 , however, suffers from poor sintering, high initial porosity, and inter-layer connected defects. In this study, an aqueous binder was used as an active carrier for the localized introduction of nano-CaTiO 3 sintering activators into the printed regions during binder jetting. Nano-CaTiO 3 -modified binders were prepared by two-step ball-milling, dilution, and sequential filtration, and their stability, rheology, jetting, and wetting behavior were evaluated. Binders with 3–9 wt% nano-CaTiO 3 enabled stable piezoelectric jetting and powder-bed penetration. After sintering at 1600 °C, open porosity decreased from 51.15% to 35.43%, flexural strength increased from 11.36 to 28.19 MPa, and roughness decreased from 10.66 to 5.42 μm. XRD and SEM–EDS support the formation of Ti-containing interfacial reaction products, while XPS indicates changes in the local chemical environment. Ca-related defect modification is proposed as a possible contribution.