When Ceramics Flow: Science Behind Rheological Behavior and Stability of Zirconia Suspensions for Digital Light Processing

When Ceramics Flow: Science Behind Rheological Behavior and Stability of Zirconia Suspensions for Digital Light Processing

Abstrakt

The rheology of ceramic suspensions suitable for DLP (Digital Light Processing) printing is an essential part of suspension analysis for creating a defect-free ceramic body. Key parameters in the fabrication of a ZrO2 body include volume filling, type of selected resin and zirconia powder, printing temperature, dispersing agent, and suspension homogeneity. All these factors mentioned affect the dynamic viscosity of the prepared suspension; therefore, it is crucial to predict the viscosity of the prepared system in DLP printing technologies. To improve the characterization of the behavior of suspensions, the new rheological model, designed for photocurable ceramics suspensions, was proposed with the formula : ηrel. = A + sinh^β*(Φ/C) where ηrel. means relative viscosity; Φ is a volume filling; and A, β, and C are mathematically derived parameters with physical meaning. Parameter A in this equation represents the system’s response to an infinitesimal increase in concentration. Parameter β amplifies the system’s response to the presence of dispersed particles. It governs the strength of the nonlinear response of the system to increasing particle concentration. The parameter C in the empirical model can be interpreted as a curvature factor that governs the rate at which viscosity increases with particle concentration. Additionally, the new model do not require knowledge of maximum volume filling, which is often distorting parameter. Furthermore, we proposed a new method for verifying the kinetic stability of prepared suspensions, a factor often neglected in rheological measurements. Using the LUMiSizer analytical centrifuge, not only did we ensure the stability of the measured photocurable zirconia suspensions (we excluded agglomeration of particles and confirmed a low level of sedimentation), but we were also able to ensure the optimal concentration of the dispersing agent for the formation of the suspension with the newly designed technique.

The rheology of ceramic suspensions suitable for DLP (Digital Light Processing) printing is an essential part of suspension analysis for creating a defect-free ceramic body. Key parameters in the fabrication of a ZrO2 body include volume filling, type of selected resin and zirconia powder, printing temperature, dispersing agent, and suspension homogeneity. All these factors mentioned affect the dynamic viscosity of the prepared suspension; therefore, it is crucial to predict the viscosity of the prepared system in DLP printing technologies. To improve the characterization of the behavior of suspensions, the new rheological model, designed for photocurable ceramics suspensions, was proposed with the formula : ηrel. = A + sinh^β*(Φ/C) where ηrel. means relative viscosity; Φ is a volume filling; and A, β, and C are mathematically derived parameters with physical meaning. Parameter A in this equation represents the system’s response to an infinitesimal increase in concentration. Parameter β amplifies the system’s response to the presence of dispersed particles. It governs the strength of the nonlinear response of the system to increasing particle concentration. The parameter C in the empirical model can be interpreted as a curvature factor that governs the rate at which viscosity increases with particle concentration. Additionally, the new model do not require knowledge of maximum volume filling, which is often distorting parameter. Furthermore, we proposed a new method for verifying the kinetic stability of prepared suspensions, a factor often neglected in rheological measurements. Using the LUMiSizer analytical centrifuge, not only did we ensure the stability of the measured photocurable zirconia suspensions (we excluded agglomeration of particles and confirmed a low level of sedimentation), but we were also able to ensure the optimal concentration of the dispersing agent for the formation of the suspension with the newly designed technique.

SOKOLA, P.; PTÁČEK, P.; KALINA, M.

10.05.2026

Jožef Stefan Institute

Ljubljana

yCAM 2026

110

110

1