Composite Extrusion Modeling (CEM) is a material extrusion process (MEX) which combines the well established injection moulding process with an innovative additive manufacturing technique. Standard injection moulding feedstocks from a wide range of materials (plastics, metals, ceramics) can be used. However, conventional highly-filled feedstocks from ceramic injection moulding consist of different polymer binder systems which complicates parameter finding in printing, debinding and sintering. To date, there is no binder system specifically adapted to the CEM process that ensures optimized process results.

In this work, a specific CEM-adapted binder system consisting of three different polymer components was developed for ceramic granulate feedstocks. The advantage of the binder system is the use of environmentally friendly components which can easily be removed in water. The initially selected aluminium oxide powder and the components of the binder system were characterized in terms of particle size, morphology and viscosity, respectively, to obtain a highly-filled polymer starting material. Different material compositions were processed into a granulate feedstock, printed in the CEM process and the additively manufactured parts were characterized. The final density after sintering for a 3D printed aluminium oxide part was 3.932 ± 0.024 g/cm3.

Subsequently, the established binder formulation can be transferred to different ceramic material classes such as oxides (ZrO2), nitrides (Si3N4) and carbides (SiC) by adjusting the powder content and binder components.