Rheology control of CO2 curable ceramic powder for binder jetting

Binder jet additive manufacturing produces three-dimensional shapes by jetting a binder or activator onto a powder bed. For successful production of 3D-printed green body, it is crucial that the rheological properties of the powder are suitable for binder jetting. In this study, the addition of a small amount of hydrophilic nanosized silica fume controlled the flowability and wettability, enabling precise control of the rheological properties of the powder for binder jetting. Calcium aluminate cement (CAC) powder was introduced to the powder bed as a binder, and 97 % deionized water was used as an activator to manufacture a CAC-based ceramic green body (CT-G). CT-G underwent CO₂ curing in a pressure reactor at 99.9 % CO₂, 4 bar pressure, and > 60 % relative humidity, and at 25 ℃ for 2, 12, 24, 48, and 72 h (CT-xC). The CT-24C sample showed significantly improved mechanical properties after a short period of CO₂ curing of 24 h, and successfully immobilizing 12 wt% CO₂ within the CAC-based material matrix. This study presents an easily implementable method for rheological control of ceramic powder to achieve successful binder jetting.