Gas Desorption Property of Inner Coating Graphite Used for Cathode Ray Tube

Effect of exposure to the atmosphere after baking in the atmosphere

Abstract

For inner coating graphite baked in the atmosphere, gas desorption properties after exposure to the atmosphere were investigiated by using a thermal desorption spectroscopy. The temperature and the water vapor pressure during the exposure were varied from 25 to 50°C, and from 950 Pa to 6150 Pa, respectively. In the heating up to 410°C, the major gas species desorbed were CO₂ and H₂O. In the thermal desorption spectra of CO₂and H₂O, a desorption peak was observed at around 130°C. The peak intensities decreased with increases of both the exposure temperature and the water vapor pressure. When the water vapor pressure increased, the desorption amount of H₂O increased, although that of CO₂ decreased. The total desorption amount was almost the same even when the water vapor pressure was changed. In order to lengthen a life time of a cathode ray tube, it is necessary to reduce the water vapor pressure in the atmosphere environment, since the cathode is damaged by mainly the water.