Simulation of Extrusion of High-Viscosity Pastes by a Piston Dosing Mechanism

A theoretical study of extrusion of a paste consisting of a silver powder in a terpineol binder is performed, aimed at getting an insight into the system’s behavior and determining the optimal conditions of the dosing mechanism operation. The paste is treated as a non-Newtonian fluid, and its characteristic properties are taken from the experiment. The spatial distributions of its viscosity, motion velocity, and excessive pressure are plotted for the characteristic cross-section of the paste during its extrusion. The viscosity distribution map is obtained as a function of the paste velocity and the distance from the nozzle during extrusion. It is shown that a pseudo-plastic behavior of the paste plays a decisive role in selecting the nozzle-to-substrate distance and determines the quality of the resulting film. The curves of dependence presented in the study would serve optimizing the extrusion process using a piston dosing mechanism.