| 摘要 |
1,214,351. Stoichiometric SiC coatings. UNITED AIRCRAFT CORP. 15 Feb., 1968 [24 Feb., 1967], No. 7446/68. Heading C1A. Silicon carbide is stoichiometrically deposited from the vapour phase on to a resistively heated filament by drawing the filament through a reaction zone at a temperature of 1130-1400‹ C. and exposing to a gas stream comprising CH 3 SiHCl 2 , H 2 and a hydrocarbon gas, e.g. CH 4 . The CH 3 SiHCl 2 /H 2 molar ratio is preferably between 1 : 1 and 1 : 3 and the hydrocarbon gas may comprise 15À3-57 mole per cent of the gas flow. The filament may be a boron coated wire. In the preferred embodiment, a condenser is employed to yield a mixture of fixed dew point, e.g. 12-15‹ C. using H 2 or Aq as a carrier gas. In Fig. 2, H 2 is introduced through a conduit 60, pressure regulator 62, flowmeter 64 and a valve 66 to the evaporator 68. Part of the H 2 is bubbled through CH 3 SiHCl 2 70 on the evaporator 68 and the mixture is discharged through a conduit 72 to a condenser 74. The output is fed through an inlet 10 into the reactor 4 through which the filament 2 is drawn. A portion of H 2 may bypass the evaporator and be introduced through a line 76 to a throughway valve 80 for purging and/or finer control of the H 2 content of the reactant mixture. Cooling H 2 is admitted through the inlet 8 from the condenser 82. Methane is introduced through a conduit 90, valve 92 and a flowmeter 94. Fig. 1, not shown, illustrates in more detail the construction of reactor 4. |
