New Feedstock System for Fused Filament Fabrication of Sintered Alumina Parts

Only a few 3D-printing techniques are able to process ceramic materials and exploit
successfully the capabilities of additive manufacturing of sintered ceramic parts. In this work, a new
two component binder system, consisting of polyethyleneglycol and polyvinylbutyral, as well stearic
acid as surfactant, was filled with submicron sized alumina up to 55 vol.% and used in fused filament
fabrication (FFF) for the first time. The whole process chain, as established in powder injection molding
of ceramic parts, starting with material selection, compounding, measurement of shear rate and
temperature dependent flow behavior, filament fabrication, as well as FFF printing. A combination of
solvent pre-debinding with thermal debinding and sintering at a reduced maximum temperature due
to the submicron sized alumina and the related enhanced sinter activity, enabled the realization of
alumina parts with complex shape and sinter densities around 98 % Th. Finally the overall shrinkage
of the printed parts were compared with similar ones obtained by micro ceramic injection molding.