Effects of Binder Content and Dispersion Strategy on Porosity in Extrusion Additive Manufacturing of ZrB 2 –SiC Ceramic

This study examined the effects of binder content and dispersion on aqueous ZrB 2 –SiC ceramic paste and the porosity of ZrB 2 –SiC ceramic parts fabricated using an extrusion‐based additive manufacturing process. An aqueous paste of ZrB 2 –SiC (70/30 by volume) powder with a 45 vol.% solids loading and hydroxypropyl methylcellulose as the binder was used. Printability was evaluated by fabricating specimens at different volumetric flow rates to identify a suitable binder content that ensures stable extrusion and shape retention in this material system. Increasing binder content reduced the density of sintered ZrB 2 –SiC cast specimens, with relative density decreasing from 98.0 ± 0.4% at 0.5 wt.% binder to 87.0 ± 1.0% at 3.0 wt.% binder, along with corresponding changes in pore morphology. This paper also reports the effects of an alternative homogenization procedure using a pre‐dissolved aqueous binder solution on the density and pore size distribution of the sintered parts. The pre‐dissolved aqueous binder solution reduced pore density compared to incorporating the binder in the dry powder form into the ceramic slurry. This study is significant for extrusion‐based ceramic additive manufacturing, particularly in fabricating functional parts where the number of large pores must be controlled.