Phenolic Carbon Fiber Composite Inks for the Additive Manufacturing of Carbon/Carbon (C/C)

Additive manufacturing (AM) is a crucial development area for high temperature, inorganic and ceramic materials which, using conventional methods, are difficult to process into complex shapes. In particular, carbon/carbon (C/C) composites produced using AM techniques are underexplored compared to other ceramics and ceramic matrix composites. This work investigated and optimized the development of phenolic resin/carbon fiber inks for the material extrusion technique of direct ink writing (DIW) to form C/C composites. Utilizing recent advances in the material extrusion of ceramics, namely the DIW preceramic polymers and preceramic polymer-based suspensions or slurries, we were able to create C/C composites. AM processes can be used to obtain complex geometries and material extrusion processes also facilitate the alignment of high aspect ratio fillers, like carbon fiber, which affects material properties like strength or stiffness. Formulation of material extrusion inks from phenolic resole resin, pitch-based milled carbon fiber as a reinforcement, and a low-density carbon black filler is reported herein. The effects of carbon fiber content and filler, which was used to obtain a printable rheology and appreciable yield stress are discussed in the context of printability.