Work at Courtaulds, Coventry

5 Work at Courtaulds, Coventry 3.4.5.1 Carbon fiber production 

Early work for producing high modulus fiber used a resistive heated furnace with a British Acheson grade CS graphite tube element, with power fed to each end through a 

Courtauld s grade 1967 Courtauld s grade post 1969 RAE equivalent grade Density gem Filament diameter pm Filament tensile strength GPa Filament tensile modulus GPa Typical ILSSof composite MPa  

When the carbon fiber product was removed from the boat, it was bound with some products of carbonization and formed a stiff tow, but when such a tow was passed between the fingers the tow became limp. This boat process ensured that the fiber was heat treated in proximity to the products of carbonization (also called cooking in its own juices ), which certainly did have beneficial properties, presumably healing surface flaws. When continuous fiber first went onstream, the strength of the continuous carbon fiber product was about 0.5 GPa below the strength of the staple product and was attributed to a change in the furnace atmosphere. 

There was an urgent requirement to produce a continuous carbon fiber and at first, a process was developed to produce a continuous high modulus material, which was then currently in demand and a continuous HT fiber followed by early 1969. The first stage of a 25 tpa plant came on stream towards the end of 1969, making Grafil A, made at 1100°C and by the end of 1970, the line was in full production for all types of fiber. 

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