| 摘要 |
1479218 Non-woven carbon fibre fabrics UNION CARBIDE CORP 26 Sept 1975 [27 Sept 1974] 39442/75 Heading C1A [Also in Divisions B5 and C5] Self bonded webs of non-woven carbon fibres are made by spinning carbonaceous pitch fibre from a non-thixotropic carbonaceous pitch having a mesophase content of 40-90% by weight, said mesophase, under quiescent conditions, forming a homogenous bulk mesophase having coalesced domains in excess of 200 microns in size; disposing staple lengths of the spun fibre in intimately contacting relationship to form a non-woven fibrous web; heating the web in an oxidizing atmosphere for a time sufficient to thermoset the surfaces of the fibres so that they maintain their shape on heating at higher temperatures but the interior portions of the fibres are not set; optionally superposing layers of the web to form a laminate; heating the web under pressure in an O 2 -free atmosphere to a temperature sufficient to cause the mesophase pitch in the unset interior portions of the fibres to undergo liquid flow and exude through the surfaces of the fibres and contact the surfaces of adjacent fibres and further heating the web to a carbonizing temperature in an O 2 -free atmosphere to produce a fabric wherein the fibres are bonded to each other by infusable carbon bonds. The fabric may be further heated to graphitize it. The pitch is preferably spun at 310-450‹ C. and staple lengths of the fibre may be formed into a web by chopping into lengths and wet or dry laying, paper making techniques or are preferably blow spun on to an endless wire conveyer belt which is used to transport the web through the oxidizing atmosphere, said oxidizing atmosphere being circulated downwardly through the web and belt. The web preferably has an areal density of 0À05 -0À5 kg./m. The fibres are preferably oxidized by passage through a plurality of heating zones having progressively higher temperatures to an oxygen content of 1-6% by weight. The oxidizing atmosphere may be O 2 , NO or preferably air. The web, possibly after lamination, is then heated in a non-oxidizing atmosphere to 1000- 2500‹ C. under pressures of 0À1-5 kPa. The web is preferably transported through the carbonizing oven on an endless carbon cloth conveyer belt. |
