| 摘要 |
1280648 Silicon carbide whiskers LAPORTE INDUSTRIES Ltd 20 Aug 1970 [29 Aug 1969] 43135/69 Heading C1A Silicon carbide whiskers are prepared by reacting silicon or a silicon alloy with a gaseous source of fluorine at above 1050‹ C. and 100 mm. Hg and reacting the product thereof with a gaseous carbon-containing compound. Where a silicon alloy is used it preferably contains at least 50% Si and a refractory oxide e.g. alumina may be present with the silicon or silicon alloy. The fluroine source may be F 2 , HF, SiF 4 , CF 4 or fluorine compounds containing both carbon and silicon and may be diluted with e.g. H 2 or Ar. The gaseous carbon source may be CO or hydrocarbons, e.g. CH 4 , C 2 H 6 , C 3 H 8 , cyclohexane, benzene, toluene, xylene. The gaseous carbon source may be added with the fluorine source or after the silicon-fluorine source reaction, in the former case the carbon source and the fluorine source may provide a F : C ratio of 10 : 1 to 1 : 10. The temperature in the first reaction zone may be up to 1800‹ C. and in the SiC whisker forming zone may be at least 50‹ C. lower than in the first zone, suitably between 1000‹ and 1550‹ C. Deposition of SiC whiskers may be facilitated by provision of suitable substrates such as carbon, silicon carbide, alumina or mullite. |
