Barium calcium aluminate impregnant materials: Interaction with Sea-Level Ambient Atmospheres and Decomposition Behaviors of Reaction Products

摘要

It has long been recognized that aluminate-type impregnant materials, as used in dispenser cathodes, react with certain constituents of the sea level ambient atmosphere. Several potentially damaging consequences of such reactions have been noted. One is "blooming", or the appearance of small amounts of impregnant-derived reaction products on the cathode surface, typically at pore ends, resulting in a hazy appearance, and which, in the extreme, as a result of significant volume expansion may crack the surrounding cathode matrix. A second issue is the possibility of detrimental chemical reactions involving the evolving decomposition products which can occur during heating of the cathode subsequent to exposure.