Simulation of shrinkage during sintering of additively manufactured silica green bodies

Green bodies with ceramic particles and polymer binders can be shaped with additive manufacturing (3D-printing) techniques without the need for a mold. The dimensions and properties of the final ceramic part produced from printed green bodies depend on the porosity created from polymer burn-off and the densification of the ceramic particles during the post-printing steps. Predictions of the part dimensions and the internal stress states of the final ceramic part can assist the designers in properly sizing and shaping the green body. In this paper, the SOVS model was implemented in a three-dimensional finite element software as a user-defined creep model. The parameters required for the SOVS model, namely viscosity and surface energy, were calibrated by minimizing the error between predicted and experimental relative densities. The parameters were obtained using an error measure definition and minimizing the error with the well-known Differential Evolution global optimization. The dimensional changes of selected additively manufactured green bodies through the polymer burnoff and sintering process are analyzed. Density changes are tracked through the time-temperature cycles typically used to create ceramic parts from their green bodies.