Adapting Extrusion Deposition Additive Manufacturing for Carbon/Carbon Composites

Carbon/carbon composites are attractive for hypersonic flight applications because of their low coefficient of thermal expansion and high specific strength at temperatures above 3000in non-oxidizing atmospheres, but the conventional manufacturing methods used for shaping this material into structural components with oriented fibers can increase costs. The use of molds/tooling surfaces and lack of automation via filament winding, resin transfer molding, autoclave processing, and textile processing (e.g. braiding, stitching, knitting, weaving) for manufacturing certain geometries introduces scalability issues and high labor costs during carbon/carbon preform production. As a result, this study explored the practicality of extrusion deposition additive manufacturing (EDAM) for producing complex-shaped carbon/carbon composites. Compared to other additive manufacturing methods, EDAM can both orient fibers and be scaled to produce large dimensionally stable structures. The investigations began with a comparison of the size- and shape- preserving-pyrolysis-processing capability of several fiber-reinforced thermoplastic polymers to identify the most dimensionally stable material, followed by X-ray micro-computed tomography scans to observe porosity changes during densification. After several phenolic resin densification cycles, the mechanical properties were measured via impulse, tension, and double-notched shear tests to gain better insight into the performance of carbon/carbon composites prepared from 3D printed preforms.