PROCESS FOR FABRICATING AN ARTICLE INVOLVING HEAT TREATMENT WITH GASEOUS REACTANTS

摘要

The invention provides a process capable of heating sol-gel tubes, or other bodies, in a manner that both limits the amount of undesirable condensation on cooler surfaces and also promotes heating and treatment with gaseous reactants in a uniform manner. In one embodiment, the process involves the steps of providing a furnace comprising a tubular muffle having an opening at one end; placing tubes or other bodies into the muffle through the opening; placing within the muffle, just inside the muffle opening, a cylindrical heat and gas shield, e.g., a plug; sealing the muffle opening with a door; heating the tubes; and treating the tubes by directing the gases through a feed hole located in the door or elsewhere in the muffle. The heat-gas shield controls the amount of heat reaching the door, thereby maintaining the integrity of the o-ring. It is also possible in other embodiments for the shield to control the extent to which both process gases and condensable materials driven from the tubes are able to back diffuse toward the muffle door, thereby reducing or avoiding condensation of the materials on the door as well as undesirable reactions between the process gases and the o- ring seal.