| 摘要 |
A composite article comprising a pyrolytic graphite matrix and 0.5-95% (atomic) of a dispersed metallic carbide and/or boride is produced by heating a substrate such as graphite, W or Mo to 1300 DEG -2500 DEG C. in a gas flow of a pyrolytic mixture containing the required metal, boron and carbon constituents at a pressure of 0.5-100 mms Hg. The following gases may be used in the pyrolytic mixture: - SiCl4, HfCl4, TaCl5, Mo and W carbonyls, trimethylchlorosilane, dimethyldiborane, zirconium cyclopentadienyl, methane, xylene, trimethylborate and boron trichloride. The pyrolytic reaction takes place in a carbon resistance furnace in which a graphite, W or Mo tube is placed and the gas mixture is passed through the tube where deposition of the carbide and/or boride and graphite takes place. Examples are given of the following coatings on graphite: SiC - C; HfB - C; HfC - C; HfC - HfB - C; TaC - C; TaC - HfC - C.ALSO:A composite article comprising a pyrolytic graphite matrix and 0.5-95% (atomic) of a dispersed metallic carbide and/or boride is produced by heating a substrate such as graphite, W or Mo to 1300-2500 DEG C. in a gas flow of a pyrolytic mixture containing the required metal, boron and carbon constituents at a pressure of 0.5-100 mm. Hg. The following gases may be used in the pyrolytic mixture: SiCl4, HfCl4, TaCl5, Mo and W carbonyls, trimethylchlorosilane, dimethyldiborane, zirconium cyclopentadienyl, methane, xylene, trimethylborate and boron trichloride. The pyrolytic reaction takes place in a carbon resistance furnace in which a graphite, W or Mo tube is placed and the gas mixture is passed through the tube where deposition of the carbide and/or boride and graphite takes place. Examples are given of the following coatings on graphite: SiC-C; HfB-C; HfC-C; HfC-HfB-C; TaC-C; TaC-HfC-C. |
