Material extrusion and sintering of binder-coated zirconia: Comprehensive characterizations

Abstract

Material extrusion processes have been increasingly employed in the fabrication of advanced ceramics in the aerospace, automotive, and biomedical fields. Such processes—which involve printing compositions containing ceramic powders and sacrificial binder, debinding the binders, and sintering the parts to obtain pure ceramics—can be used to produce more complex structures than traditional ceramic manufacturing techniques. In this study, a rod-shaped feedstock comprised of binder-coated zirconia containing 87 wt% zirconia was supplied to a motorized piston extruder in a customized 3D printer to fabricate green ceramic structures, and the structures were then subjected to debinding and sintering. A comprehensive set of characteristics were examined: the thermal and rheological properties of the feedstock, the printability of the feedstock, the influence of the layer thickness and raster angle on the surface roughness and flexural/tensile/compressive strengths of the sintered zirconia, Vickers hardness, relative density and porosity, shrinkage behavior, and the micro/macro structure of green and sintered 3D-printed zirconia structures. The mechanical properties and relative density were found to increase as the layer thickness decreased. The maximum flexural, tensile, and compressive strengths of the sintered zirconia were 435, 36.13, and 689 MPa, respectively, and the relative density was 98.85% at a layer thickness of 200 µm. The comprehensive characteristics of 3D printed green and sintered zirconia that were obtained in this study can facilitate the successful 3D printing of ceramics. Moreover, the characterization contributes to an understanding of the effects of additive manufacturing process parameters on the physical and mechanical properties of ceramic materials and can aid in optimizing the performance and properties of 3D printed ceramic structures. • Comprehensive characterizations of green and sintered zirconia parts was conducted. • A binder-coated zirconia was developed for material extrusion additive manufacturing. • A piston-based extrusion process was developed to fabricate highly dense zirconia parts. • Defect-free zirconia structures were produced using solvent and thermal debinding, followed by sintering.