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Effect of sintering atmospheres on the structure and properties of the 612 type barium-calcium-aluminate for the dispenser cathodes.
- Source :
-
Ceramics International . Aug2019, Vol. 45 Issue 12, p14816-14820. 5p. - Publication Year :
- 2019
-
Abstract
- The effects of air, hydrogen, and CO 2 and O 2 mixture sintering atmospheres on the structure, micromorphology, electron emission capability and environmental stability of 612 type barium-calcium-aluminates have been investigated. Both the 6BaO-1CaO-2Al 2 O 3 aluminates sintered in air and hydrogen crystallize in the Ba 3 CaAl 2 O 7 phase. However, the aluminates with the same composition sintered in CO 2 and O 2 mixture crystallizes in the Ba 3 Al 2 O 6 phase with a small amount of BaCO 3 reactant. The microstructure for the aluminates sintered in air and H 2 show similar features while the sample sintered in CO 2 and O 2 mixture atmosphere shows better conglomeration. Emissivity tests indicate that the divergent current density J div for the dispenser cathodes impregnated with aluminates sintering in air, H 2 , and CO 2 and O 2 mixture atmospheres are 6.0, 6.1, and 7.6 A cm−2 at 1130 °C B , respectively. Finally, environmental stability tests indicate that the aluminates with the Ba 3 CaAl 2 O 6 phase sintered in air as well as hydrogen is more environmentally stable than that with Ba 3 Al 2 O 6 phase sintered in CO 2 and O 2 mixture. The process of sintering 612 aluminate in CO 2 and O 2 mixture is beneficial for superior emissivity on the condition of avoiding exposure to moisture. [ABSTRACT FROM AUTHOR]
- Subjects :
- *ELECTRON emission
*CATHODES
*ATMOSPHERE
*BARIUM
*ALUMINATES
*DENSITY currents
Subjects
Details
- Language :
- English
- ISSN :
- 02728842
- Volume :
- 45
- Issue :
- 12
- Database :
- Academic Search Index
- Journal :
- Ceramics International
- Publication Type :
- Academic Journal
- Accession number :
- 136843573
- Full Text :
- https://doi.org/10.1016/j.ceramint.2019.04.212