The material is made in three stages: First, material is laid up in its intended final shape, with carbon filament and/or cloth surrounded by an
organic binder such as plastic or
pitch. Often,
coke or some other fine carbon
aggregate is added to the binder mixture. Second, the lay-up is heated, so that
pyrolysis transforms the binder to relatively pure carbon. The binder loses volume in the process, causing voids to form; the addition of aggregate reduces this problem, but does not eliminate it. Third, the voids are gradually filled by forcing a carbon-forming gas such as
acetylene through the material at a high temperature, over the course of several days. This long
heat treatment process also allows the carbon to form into larger
graphite crystals, and is the major reason for the material's high cost. The gray "Reinforced Carbon–Carbon (RCC)" panels on the space shuttle's wing leading edges and nose cone cost NASA $100,000/sq ft to produce, although much of this cost was a result of the advanced geometry and research costs associated with the panels. This stage can also include manufacturing of the finished product. The material has a density between 1.6 and 1.98 g/cm3. ==Similar products==