Ink development for the additive manufacturing of strong green parts by layerwise slurry deposition (LSD-print)

Obtaining dense fine ceramics by the binder jetting additive manufacturing process is challenging. A slurry-based binder jetting process, such as the layerwise slurry deposition (LSD-print) process, can enable the printing of dense ceramic parts. This work describes a procedure to develop and qualify a suitable ink to manufacture silicon carbide green parts by LSD-print. Not only the printability but also the compatibility of the ink with the powder bed and the effect of the binding agent on the properties of the green parts are considered. Both aspects are important to obtain high green strength, which is necessary for printing large or thin-walled parts. Characterization methods, such as rheological and surface tension measurements, are applied to optimize three selected inks. The interplay between ink and powder bed is tested by contact angle measurements and by comparing the biaxial strength of cast and additively manufactured specimens. Out of the three binding agents tested, a polyethyleneimine and a phenolic resin have a high potential for their use in the LSD-print of silicon carbide green bodies, whereas a polyacrylate binding agent did not show the required properties.