Tannic acid metal ion coordination network: a green and efficient new strategy for regulating the rheological properties of ceramic slurries.

To address the environmental, cost, and process compatibility challenges associated with traditional dispersants in wet forming of high-performance ceramics, this study systematically investigates the effects of tannic acid (TA) and its complexes with metal ions from ceramic matrices on the rheological properties and mechanical performance of dried ceramic slurries. Rheological analyses were conducted on multiple ceramic systems-including Al/Si-based components and pure SiO2-under varying TA concentrations and water content conditions, and the underlying mechanisms were elucidated. The results indicate that TA alone reduces slurry viscosity, while the rapid formation of nanoplate-like TA-Metal ions complexes significantly enhances fluidity, achieving a viscosity reduction of up to one-ninth of the original value under the same conditions of moisture content and shear rate. The reticular network structure of TA-metal ion complex functions as an interparticle buffer zone, suppressing particle collisions and interfacial friction, and consequently reducing slurry viscosity. As a naturally sourced, economical, and effective modifier, tannic acid and its metal complexes offer a green strategy for optimizing the rheological behavior and forming quality of ceramic slurries used in wet forming, and provide a scalable and sustainable pathway for manufacturing high-performance functional ceramics.