Carbon fibre is an ideal material for reinforcing inorganic matrix composites, especially for high temperatures. Its main drawback is its susceptibility to oxidation and to reaction with metals.
Our challenge was to perfect a method of producing a carbon fibre in which each elementary filament is covered and protected by a very thin and adherent layer of a refractory carbide such as SiC, B4C, etc…
For this purpose, we use reactive chemical vapor deposition (R.C.V.D.) in which only the M element of the M C carbide is carried by the gas phase, carbon being supplied by the fibre itself. The growth rate is self regulated by the solid state diffusion.
This method has been developed in a continuous reactor with ex-PAN (6K) or ex-PITCH (2K) fibres.
The mechanical behaviour of the coated fibres is very near that of the initial ones, but their oxidation rate at 600°C is 100 times lower.