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

Additive manufacturing or 3D printing has emerged as a viable alternative for the mould-less fabrication of monolithic ceramics. However, the practical printing of ceramic-based composites combining different materials still presents a difficult challenge. In particular, printing composites with long or continuous fibre while engineering the fibre-matrix interfaces has proven difficult. Here we will show how direct ink writing can be used to print ceramic composites reinforced by long fibres by extruding core-shell filaments based on thermally reversible inks. The diameters of the fibres can go below 50 microns. The approach also enables the extrusion of filaments with thin interlayers between the core and the shell that can be used to engineer the fibre matrix interface. Here, we demonstrate this concept by extruding filaments with a hard and brittle shell (alumina) and a ductile core (steel, 430L). We show how this approach allows the fabrication of cellular and dense structures that retain the ceramic strength and stiffness but exhibit works of fracture that can be up to 2 orders of magnitude above the one of the ceramic matrix.