Ceramic fused filament fabrication (CF3) of zirconia implants by using flexible, partially water-soluble binder systems

• Highly flexible filaments with 50 vol% solids content with excellent flow behavior. • Partially water-soluble binder eliminates the use of hazardous and expensive organic solvents. • Ability to manufacture delicate implants with complex geometries. • Final zirconia parts up to 100 % relative density after sintering without showing any defects. Ceramic Fused Filament Fabrication offers a simple and cost-effective method to manufacture personalized ceramic implants. However, the lack of flexibility in highly filled filaments and the reduced accuracy compared to alternative additive manufacturing techniques limit the method’s widespread implementation. Therefore, an eco-friendly partially water-soluble containing polyethylene glycol (PEG), poly(vinylbutyral) (PVB), and poly(methylmethacrylat) (PMMA) was investigated, along with the influence of the two additives acetyltributylcitrate (ATBC) and lauric acid (LA). The created feedstocks were characterized by comprehensive rheological analysis, which included capillary rheology and dynamic mechanical analysis. The production of filaments with a solid content of 50 vol% was successfully achieved, demonstrating exceptional flexibility and flow properties. Following the debinding and sintering processes, the optimal feedstock systems enabled the fabrication of defect-free components with a high level of detail and relative densities up to 100 %.