A Comparative Study of CMC and HPMC Binders for Direct Ink Writing of Ceramics

ABSTRACT The selection of binders in ceramic additive manufacturing plays a high role in determining the feasibility and quality of printed components. This study investigates the performance of sodium carboxymethylcellulose (CMC) and hydroxypropylmethylcellulose (HPMC) as bio‐based binders in aqueous alumina suspensions for direct ink writing (DIW). CMC, characterized by its polyelectrolyte nature, demonstrated rapid dissolution, exceptional dispersion stability, and consistent rheological properties, facilitating smooth extrusion and the formation of high‐quality surfaces. These characteristics are critical for DIW, where ink homogeneity and stability directly impact printing resolution and part integrity. HPMC, by contrast, exhibited slow dissolution, thermally induced gelation, and printing inconsistencies, likely due to its lack of electrostatic stabilization. Microstructural and mechanical evaluations of sintered parts confirmed that CMC‐based systems achieved higher density, homogeneity, and microhardness. This study highlights the significance of CMC as a binder, providing a pathway to overcome common challenges in DIW, such as agglomeration, foaming, and poor sintered properties, while enabling the production of high‐performance ceramic components.