| 摘要 |
A method for direct covering graphite and ceramic coal crucibles with pyrocarbon and pyrographite coatings by putting a crucible in a chamber of a high-temperature furnace, lowering pressure, gradual raising temperature up to 1,300 - 2,500 K and delivering carbonic gas, possibly with some inert gas added, for a period of time required to achieve a desired thickness of a layer. The method is distinctive in that each crucible placed inside a furnace chamber is equipped with a separate screen in order to ensure forced circulation of carbon gas along coated crucible surfaces. Each crucible is supplied with carbon-carrying gas through a separate feed pipe inserted into a crucible as deep as 0.3-0.8 of its height. The inner crucible diameter to outer feed pipe diameter ratio is 1.3-3.0. The amount of delivered carbon is (2-8)x10<-3> carbon mole per 1 square centimetre of covered surface per hour.<IMAGE>
|
