Formation and surface properties of electron‐emissive coatings. IX. Thermal decomposition of the alkaline‐earth formates

Abstract

AbstractThe thermal decomposition of alkaline‐earth formates under vacuum has been studied because of the use of barium formate as a binder for cathode coatings. Techniques employed in this work include thermogravimetry, differential thermal analysis and evolved gas detection, in conjunction with gas chromatography and infrared absorption spectroscopy for identification of the gaseous decomposition products.Decomposition occurs in two stages; the first results in formation of carbonate plus a small amount of free carbon. The second stage involves initially reaction of the free carbon with carbonate to form carbon monoxide and the corresponding alkaline earth oxide. Then, at a higher temperature, thermal decomposition of the carbonate itself commences, leading to the formation of the oxide plus carbon dioxide. With calcium formate, the two carbonate decomposition processes occur concurrently; but with strontium and barium formates, reaction with free carbon commences at a significantly lower temperature than thermal decomposition of the pure carbonate.