EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The Lithography-based Ceramic Manufacturing (LCM) technology has been established as promising technique for fabricating complex-shaped ceramics based on a layer-by-layer photo-polymerisation process. In recent times, much effort has been dedicated to investigate the mechanical response of 3D-printed bulk alumina.

In this work we employ the LCM technology to 3D-print alumina-based ceramics with unprecedented mechanical strength. The design of the materials uses the layer-by-layer capabilities of the printing process and is based on a multi-material approach. The combination of alumina with alumina-zirconia layers introduces compressive residual stresses in the surface layers associated with the different shrinkage of the combined materials during cooling down from sintering. The effect of compressive residual stresses on the strength of 3D printed alumina-zirconia based multilayers (designed with outer alumina layers) is investigated under biaxial bending tests and compared to 3D printed bulk alumina material. Results are analysed in the framework of Weibull statistics. A characteristic biaxial strength as high as 1 GPa was measured on the alumina-based multilayers, as compared to 650 MPa in bulk alumina, the difference corresponding to the magnitude of in-plane residual stresses in the external alumina layers. This work is the first report of employing additive manufacturing to tailor the strength of alumina ceramics, based on a layer-by-layer printing process. Designing complex-shaped multilayer ceramic architectures with tailored residual stresses through additive manufacturing technologies opens a new path for advanced ceramics with unprecedented mechanical behaviour.

Reference: J. Schlacher, A.-K. Hofer, S. Geier, I. Kraleva, R. Papšík, M. Schwentenwein, R. Bermejo, Additive manufacturing of high-strength alumina through a multi-material approach, Open Ceramics (2021) (submitted).