RHEOLOGICAL BEHAVIOR AND 3D PRINTING OF HIGHLY FILLED ALUMINA-POLYAMIDE FILAMENTS DURING FUSED DEPOSITION MODELING

Abstract

The present work provides evidence for the feasibility of green body printing by FDM technology using highly developed (65 wt.%) filled alumina (Al<sub>2</sub>O<sub>3</sub>) - polyamide filaments. The irregular (anisometric) particle shape of the as-received ceramic powder was changed to spherical (granulated) using the spray drying method. This shape of particles improves the flowability of the composition and are more uniformly distributed in the polymer binder. To evaluate the behavior of the created ceramic-polymer mixtures with ceramic particles of both irregular and spherical shapes during extrusion, their rheological properties were studied. The granular particles appeared to be more densely packed and homogeneously distributed in the extruded sample. Anisometric particles are worse oriented in the flow, which affects the rheological properties of the samples. For spherical particles, the effect of decreasing hydrodynamic resistance during deformation is observed. Increasing the Al<sub>2</sub>O<sub>3</sub> phase content (irrespective of the particle shape) up to 75 wt.% and decreasing the binder content leads to a significant increase in the elasticity of the samples and a change in the flow character up to its loss. The variation of diameter and surface roughness measurements of extruded filaments with irregularly shaped ceramic particles was higher than that of filament samples with spherical particles. The developed feedstock is supposed to be used for 3D printing with subsequent post-processing methods to produce ceramic samples.