Ceramic Matrix Composites (CMCs) have been gaining increasing attention as an exceptionally useful material for challenging environments such as high temperature applications in Aerospace. However, their production has so far been limited to particular geometries that can be produced by the conventional CMC manufacturing approaches, usually in the format of layered woven mats. 
 
This paper will report on early-stage, ongoing research into a novel approach of producing CMC parts through the process of extrusion. Extrusion is a highly efficient production method that is used extensively in the ceramic industry including the manufacture of architectural components such as brick and tiles. Extrusion is also utilised in the production of more technical and specialist ceramics parts, such as cathectic converters, however in the context of CMC the use of extrusion is almost completely unexplored. This research seeks to address this knowledge gap in order to extend the application of CMC by expanding the geometries that can be produced in the CMC medium and, ultimately, also address production inefficiencies with conventional approaches.    
 
The rheology that governs the flow of the ceramic paste in an extrusion situation is highly complex and theoretical modelling is currently not capable of fully predicting the quality of the extruded outcome from a particular die design. The particular composition of CMCs, with a mixture of ceramic slurry and fibre, makes theoretical modelling even more complex. Consequently, this research adopts empirical research methodologies with practical testing of CMC compositions, as well as the geometries of die the designs.  To facilitate rapid iterative research investigations the use of 3D printing technology to create the extrusion dies is being utilised in this research. This approach also allows for the creation of complex geometries and shapes that would be difficult or impossible to produce using traditional manufacturing methods. 
 
The composition of CMCs is an important factor in determining their properties and performance, however the level of performance that can be achieved with CMC produced via extrusion are, to some degree, limited by the nature of this production method, ie. extrudability.  So far, this research has focused on achieving high levels of surface resolution while at the same time aiming to maximise the content of fibre in the composites. Results are presented with CMC body compositions with different length of fibres ranging from >1mm to 12.5mm, with very promising outcomes of tests with the longer fibre. For the tests focused exploring high surface quality carbon fibres were use to aid the visual inspection of the fibre alignment in the extruded samples. Further tests are presented which explore strength tests of extruded CMC with 3M Nextel 610 fibres. 
 
In summary, this early-stage research into extrusion with CMCs using 3D printed extrusion dies is showing significant promise for the production of high-performance CMCs with geometries that would be difficult to achieve through the use of conventional CMC production methos. Further research is ongoing to optimize the process and improve the properties of the final parts.