Influence of material and process parameters on microstructure evolution during the fabrication of carbon–carbon composites: a review

Carbon–carbon composites (CCCs) are a unique form of carbon fiber-reinforced materials that exhibit excellent thermomechanical properties under extreme environmental conditions. Due to the need for the retention of mechanical properties at temperatures exceeding 2000 °C, CCCs have been utilized in heat shields, rocket nozzles, aircraft brakes, and leading edge material in hypersonic vehicles. In order to expand the applicability of CCCs, the fabrication process must be modified such that there is a reduction in cost or processing time. It is hypothesized that maximizing the permeability of the composite, during processing, will grant the largest reduction in the fabrication time as it leads to a larger volume of pores filled during re-densification. This review attempts to capture the various parameters that have led to increased permeability, as well as outlining process modifications that have demonstrated influence over the carbonized microstructure. In addition, this review seeks to differentiate itself by systematically outlining research advances that have been made in each step of the fabrication process. In doing so, scientific gaps that exist can be expounded upon while simultaneously summarizing what is necessary to advance the field.