| 摘要 |
1526809 Graphite body UNION CARBIDE CORP 26 Sept 1975 [27 Sept 1974] 39441/75 Heading C1A [Also in Division B5] A graphite body having a longitudinal coefficient of thermal expansion of less than 0À1x 10<SP>-6</SP>/‹C. is made by extruding, in an 0 2 -free atmosphere, a pitch having a mesophase content of at least 40 wt. per cent, the pitch being one which under quiescent conditions, forms a bulk mesophase having coalesced domains in excess of 100 microns; thermosetting the extruded shape in an oxidizing atmosphere; further heating the thermoset shape in an 0 2 -free atmosphere to form an oriented coke, mixing the coke, which has an aspect ratio of at least 2:1 with a carbonizable binder, e.g. pitch, in a ratio of 50-80 wt. per cent coke, 50-20 wt. per cent binder; extruding the mixture, and finally carbonizing and graphitizing the extrudate. The oriented coke may be ground or sized before mixing with the binder, provided an aspect ratio of at least 2:1 is maintained. In examples, spun fibres of mesophase pitch are used to form extruded rods of graphite. |
