Rapid processing of Al2O3 ceramics by fused filament fabrication and ultrafast high-temperature debinding and sintering

Abstract

Fused filament fabrication (FFF) is widely used for ceramic prototyping due to its compatibility with low-cost custom-made printers designed for polymers. However, the bottleneck of the whole process lies in the slow thermal debinding and sintering that are usually employed to obtain dense and defect-free ceramics. In this study, a filament with ∼79 wt% alumina powder in a thermoplastic binder was used to print gyroid structures with nozzle diameters of 0.4, 0.6, and 0.8 mm. The components were at first partially solvent-debinded (acetone) and thereafter thermally debinded and consolidated in a single step (60 s) by ultra-fast high-temperature sintering. Samples printed with a 0.4 mm nozzle diameter resisted the ultra-rapid heating (UHS) and cooling rates (∼10 3 K/min), whereas some defects appear when considering larger nozzle size. On the other hand, all samples either cracked or shattered into pieces when fast-fired in air, highlighting the relevance of the thermal debinding atmosphere. Moreover, the densification upon UHS was largely improved compared to conventional sintering while retaining a finer grain size. This work provides a guideline for the rapid debinding and firing of fused filament fabricated ceramics and could be easily extended to other ceramic systems. • In-house filaments with ∼79 wt% Al 2 O 3 were successfully fabricated. • Printed samples were thermally debinded and sintered using ultrafast high-temperature sintering (UHS) in 60 s. • Crack-free and dense samples were obtained using a 0.4 mm nozzle; however, defects were observed in samples with thicker struts. • The sintering/debinding atmosphere plays a major role, inert environments avoiding the formation of defects. • The density achieved by UHS surpasses the one obtained after conventional sintering, while retaining a finer microstructure.

Topics & Concepts