| 摘要 |
1446872 Carbon fibre sheet KUREHA KAGAKU KOGYO KK and TOYO BOSEKI KK 2 July 1973 [3 July 1972] 31340/73 Heading C1A [Also in Divisions D2 and H1] A carbon fibre sheet suitable for use as an electrode in a fuel cell is prepared by forming a carbon fibre mat by a paper making step using a furnish comprising carbon fibres and a binder therefor, impregnating the mat with a solution of a carbonizable resin, heating the mat to carbonize the resin in order to produce a mat in which the fibres are bonded by amorphous carbon, and heating the carbonized mat in the presence of a gaseous organic compound to deposit graphite or carbon on to the mat by thernal decomposition of the compound. The carbon fibres may be of amorphous carbon or graphite, or both, and preferably have a length of 1 to 10 mm. and a diameter of about 10 Á. The binder may be polyvinyl alcohol. The carbon fibres may have a random or a particular orientation. The carbonizable resin may be a phenolic resin, and may be carbonized at about 1000‹ C. The thermal decomposition step may take place at 600-2400‹ C., and suitable organic compounds include methane, ethane, propane, town gas, polycyclic compounds and derivatives thereof, and fractions from coal or coal tar. Up to 5% of inert gas may be present in the atmosphere in the thermal decomposition step. The resulting sheet may be further heated to convert amorphous carbon into graphite. The sheet may have a thickness of 0À2 to 5 mm., a porosity of 50 to 70%, and an electrical resistance of 0À05 # cm. In the example, a carbon fibre mat is produced on a paper making machine from a suspension of 3 mm. carbon fibres in an aqueous solution containing a dispersing agent and 10% by weight of polyvinyl alcohol resin. The mat is treated with 0À5% by weight of phenol solution of phenolic resin in methanol, maintained at 180‹ C. for 1 hour to set the resin, and heated at 1000‹ C. for 3 hours to carbonize the resin. The resulting mat was treated in the following thermal decomposition step at 1300‹ C. The physical properties of the carbonized mat and the final sheet are described. |
