| 摘要 |
1,223,380. Carbon fibres. GREAT LAKES CARBON CORP. 8 May, 1969 [28 May, 1968], No. 23616/69. Heading C1A. Carbon or graphite filament and yarn are prepared by stretching a continuous length of polyacrylonitrile filament or yarn in steam by at least 150% of its initial length, and then subjecting the stretched material to a two-stage non-combustive oxidation in which the stretched material is first subjected to heat treatment at a temperature of from 200‹ to 250‹ C. in a flowing oxidizing atmosphere for a period of one to two hours, the treatment being carried out whilst the filamentary material passes through a kiln in a continuous manner and under sufficient tension to substantially prevent shrinkage, and is then subjected to a second heat treatment in batch lots at a temperature of from 200-250‹ C. in a flowing oxidizing atmosphere for a period of 5 to 15 hours. The second heat treatment being performed on a fibre or yarn free from tension then carbonizing the oxidized material in a non-oxidizing atmosphere at a temperature of at least 700‹ C., preferably at least 1500‹ C. The polyacrylonitrile may be subjected to a preliminary oxidation at a temperature below 200‹ C. The preferred oxidizing atmosphere is air. The preferred combination of time and temperature for the first stage is 205‹ C. for 1 hour. The length of fibre treated may be at least 2000 feet. The fibre may be graphitized and heating schedules are given in the Specification.
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