| 摘要 |
1478898 Sintered silicon carbide GENERAL ELECTRIC CO 28 June 1974 [24 Oct 1973] 28907/74 Headings C7A and C7D A sintered B SiC ceramic body containing a B containing material selected from B or B 4 C in an amount equivalent to 0À3-3 wt per cent B and 0À1 wt per cent C and has a density at least 85% of theoretical. The ceramic is produced from a dispersion of the SiC, B material and C which is shaped to form a green body and then sintered in an inert atmosphere such as A, He, N 2 and H 2 at 1900-2100‹C. Preferably a B doped SiC dispersion is first formed from a SiO 2 gel in a solution containing sugar and boric acid which is then dehydrated and heated in an inert atmosphere. A carbonaceous additive e.g. a novolak resin, a polynuclear aromatic hydrocarbon derived from coal tar or a polymer of an aromatic hydrocarbon is then added to the B doped SiC dispersion and the mixture is pyrolyzed to decompose the carbonaceous additive. Isostatic pressing or slip casting may be used to form the SiC body. |
