When producing a structural carbon-carbon (C/C) composite material, the first step is to orientate the required volume fraction of fibres into a preform, in order to accommodate the design loads required of the final component inservice. All of the C/C preform structures must then be densified by a process that fills the open volume of the preform with a well-bonded carbon or graphite matrix. Selection of a densification process is dictated by the characteristics of the preform structure (fibre type and weave) and the required properties of the composite (matrix).
There are two main routes to producing C/C composites, carbonisation of organic liquids (polymers) impregnated into the fibre preform , and chemical vapour infiltration of carbon from gaseous hydrocarbon precursors (see Figure 1). Solid state processes are unfavourable because carbon is very difficult to sinter.