New Feedstock System for Fused Filament Fabrication of Sintered Alumina Parts.

Dorit Nötzel,Thomas Hanemann

doi:10.3390/ma13194461

Abstract

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.

Highlights

Over recent years, a huge variety of additive manufacturing (3D printing) methods have been developed, starting with polymer materials and extended nowadays to ceramics, metals, composites, or other advanced functional materials
The relevant properties of the used alumina particles have been reported earlier, the morphology obtained by SEM investigations shows mostly spherical nanosized primary particles, which are highly agglomerated (Figure 1) [23]
The measured specific surface area is relevant for the calculation of the surfactant amount needed; here an SA concentration of 3.3 mg/m2 related to the particle surface was selected guaranteeing a complete coverage of the alumina’s surface enabling the formation of a homogeneous feedstock after compounding

Summary

Introduction

A huge variety of additive manufacturing (3D printing) methods have been developed, starting with polymer materials and extended nowadays to ceramics, metals, composites, or other advanced functional materials. 3D printing can be distinguished in seven categories, namely material extrusion, material jetting, binder jetting, powder bed fusion, direct energy deposition, vat polymerization, and sheet lamination [7]. Most of these were used for the processing of polymer-based materials, like UV-curable reactive resins in case of vat polymerization (Stereolithography, SLA) or thermoplastics in the case of extrusion Whilst metal parts are mainly printed directly by the different variants of Selective Laser Sintering (SLS), Selective Laser

Methods

Results

Conclusion