GB1025285A - Improvements in or relating to the pyrolytic deposition of carbon - Google Patents

Abstract

Porous carbon, refractory or metal articles are impregnated with carbon by passing the articles slowly through a temperature-controlled reaction zone under non-oxidizing conditions while a flow of hyrolysing hydrocarbon gas is passed through the reaction vessel, preferably in the reverse direction. The reaction vessel may have several temperature-controlled regions so that a uniform temperature may be maintained along the length of the zone, or, alternatively, over a central region at least, a substantially uniform temperature gradient is maintained, in which case the articles pass from the hotter to the cooler zone. Suitable temperatures lie between 800 DEG C. and 900 DEG C. As shown, the articles to be treated, 21, in graphite carrier members 20 are inserted at end A of the reactor 11. The carrier members interlock to form a continuous line through the reactor. During initial heating of the reactor, and during insertion and removal of the carrier members, a stream of flush gas introduced at 16 is passed through the apparatus. For the treatment, hydrocarbon, e.g. benzene, is introduced via inlet pipe 15, which is slidable through gas seal 22 and end cap 23. Gas diffusing through the articles escapes along the serrations 25 of the carrier members 20 (Fig. 3, not shown). End plate 24 of pipe 15 engages with the carrier member due to enter outlet chamber 13. After a residence time of e.g. 20 hours, the carrier members are withdrawn in the direction of X, the end carrier member disengaged and removed from chamber 13 while a fresh charged carrier member is inserted at A. Those already in the tube are pushed along so that the new end carrier member engages with plate 24. <PICT:1025285/C6-C7/1>ALSO:<PICT:1025285/C1/1> In a process for impregnating porous materials such as carbon, refractory and certain metal articles with carbon, the articles are passed slowly through a temperature controlled reaction zone under non-oxidizing conditions while a flow of pyrolizing hydrocarbon gas is passed through the reaction vessel, preferably in the reverse direction. The reaction vessel may have several temperature controlled regions so that a uniform temperature may be maintained along the length of the zone, or, alternatively, over a central region gradient is maintained, in which case the articles pass from the hotter to the cooler zone. Suitable temperatures lie between 800 DEG and 900 DEG C. As shown, the articles to be treated, 21, in graphite carrier members 20 are inserted at end A of the reactor 11. The carrier members interlock to form a continuous line through the reactor. During initial heating of the reactor, and during insertion-removal of the carrier members a stream of flush gas introduced at 16 is passed through the apparatus. For the treatment, hydrocarbon, e.g. benzene, is introduced via inlet pipe 15, which is slidable through gas seal 22 and end cap 23. Gas diffusing through the articles escapes along the serrations 25 of the carrier members 20 (see Fig. 3, not shown). End plate 24 of pipe 15 engages with the carrier member due to enter outlet chamber 13. After a residence time of e.g. 20 hours, the carrier members are withdrawn in the direction of X, the end carrier member disenganged and removed from chamber 13 while a fresh charged carrier member is inserted at A. Those already in the tube are pushed along to engage with plate 24.