Influence of powder characteristics on the rheology of ceria-based screen-printing pastes for solid oxide cell applications

Screen-printing is a widely utilized method for fabricating solid oxide electrolysis cells (SOECs), a promising technology for efficient hydrogen production. This study focuses on the rheological characterization of screen-printing pastes, emphasizing the influence of ceramic powder properties on rheological behavior and layer features. Conventional metrics such as viscosity, or binder and ceramic content provided in wt% are shown to inadequately describe paste characteristics. Instead, we propose the use of dynamic rheological properties, including damping factor and yield point, and introduce a bimodality coefficient φ to be able to quantify and correlate particle size distribution shapes with these rheological properties. Results demonstrate that dry layer thickness and dimensional accuracy correlate strongly with the damping factor, revealing that pastes with higher damping factors exhibit thinner layers due to increased viscous behavior. Additionally, increasing the amount of binder in relation to the specific surface area (SSA) of the ceramic particles weakens the 3-dimensional paste network, decreasing yield points and shifting paste behavior toward predominantly viscous behavior. Analysis of SSA as well as particle size distribution (PSD) and their correlation with rheology highlights the destabilizing effect of agglomerates in asymmetrical and bimodal particle size distributions, underscoring the need for comprehensive powder characterization.